1. Introduction
This section is non-normative.
Bluetooth is a standard for short-range wireless communication between devices. Bluetooth "Classic" (BR/EDR) defines a set of binary protocols and supports speeds up to about 24Mbps. Bluetooth 4.0 introduced a new "Low Energy" mode known as "Bluetooth Smart", BLE, or just LE which is limited to about 1Mbps but allows devices to leave their transmitters off most of the time. BLE provides most of its functionality through key/value pairs provided by the Generic Attribute Profile (GATT).
BLE defines multiple roles that devices can play. The Broadcaster and Observer roles are for transmitter- and receiver-only applications, respectively. Devices acting in the Peripheral role can receive connections, and devices acting in the Central role can connect to Peripheral devices.
A device acting in either the Peripheral or Central role can host a GATT Server, which exposes a hierarchy of Services, Characteristics, and Descriptors. See § 5.1 GATT Information Model for more details about this hierarchy. Despite being designed to support BLE transport, the GATT protocol can also run over BR/EDR transport.
The first version of this specification allows web pages, running on a UA in the Central role, to connect to GATT Servers over either a BR/EDR or LE connection. While this specification cites the [BLUETOOTH42] specification, it intends to also support communication among devices that only implement Bluetooth 4.0 or 4.1.
1.1. Examples
To discover and retrieve data from a standard heart rate monitor, a website would use code like the following:
let chosenHeartRateService= null ; navigator. bluetooth. requestDevice({ filters: [{ services: [ 'heart_rate' ], }] }). then( device=> device. gatt. connect() ) . then( server=> server. getPrimaryService( 'heart_rate' )) . then( service=> { chosenHeartRateService= service; return Promise. all([ service. getCharacteristic( 'body_sensor_location' ) . then( handleBodySensorLocationCharacteristic), service. getCharacteristic( 'heart_rate_measurement' ) . then( handleHeartRateMeasurementCharacteristic), ]); }); function handleBodySensorLocationCharacteristic( characteristic) { if ( characteristic=== null ) { console. log( "Unknown sensor location." ); return Promise. resolve(); } return characteristic. readValue() . then( sensorLocationData=> { let sensorLocation= sensorLocationData. getUint8( 0 ); switch ( sensorLocation) { case 0 : return 'Other' ; case 1 : return 'Chest' ; case 2 : return 'Wrist' ; case 3 : return 'Finger' ; case 4 : return 'Hand' ; case 5 : return 'Ear Lobe' ; case 6 : return 'Foot' ; default : return 'Unknown' ; } }). then( location=> console. log( location)); } function handleHeartRateMeasurementCharacteristic( characteristic) { return characteristic. startNotifications() . then( char => { characteristic. addEventListener( ' characteristicvaluechanged ' , onHeartRateChanged); }); } function onHeartRateChanged( event) { let characteristic= event. target; console. log( parseHeartRate( characteristic. value)); }
parseHeartRate()
would be defined using the heart_rate_measurement
documentation to read the DataView
stored
in a BluetoothRemoteGATTCharacteristic
's value
field.
function parseHeartRate( data) { let flags= data. getUint8( 0 ); let rate16Bits= flags& 0x1 ; let result= {}; let index= 1 ; if ( rate16Bits) { result. heartRate= data. getUint16( index, /*littleEndian=*/ true ); index+= 2 ; } else { result. heartRate= data. getUint8( index); index+= 1 ; } let contactDetected= flags& 0x2 ; let contactSensorPresent= flags& 0x4 ; if ( contactSensorPresent) { result. contactDetected= !! contactDetected; } let energyPresent= flags& 0x8 ; if ( energyPresent) { result. energyExpended= data. getUint16( index, /*littleEndian=*/ true ); index+= 2 ; } let rrIntervalPresent= flags& 0x10 ; if ( rrIntervalPresent) { let rrIntervals= []; for (; index+ 1 < data. byteLength; index+= 2 ) { rrIntervals. push( data. getUint16( index, /*littleEndian=*/ true )); } result. rrIntervals= rrIntervals; } return result; }
onHeartRateChanged()
might log an object like
{ heartRate: 70 , contactDetected: true , energyExpended: 750 , // Meaning 750kJ. rrIntervals: [ 890 , 870 ] // Meaning .87s and .85s. }
If the heart rate sensor reports the energyExpended
field,
the web application can reset its value to 0
by writing to the heart_rate_control_point
characteristic:
function resetEnergyExpended() { if ( ! chosenHeartRateService) { return Promise. reject( new Error( 'No heart rate sensor selected yet.' )); } return chosenHeartRateService. getCharacteristic( 'heart_rate_control_point' ) . then( controlPoint=> { let resetEnergyExpended= new Uint8Array([ 1 ]); return controlPoint. writeValue( resetEnergyExpended); }); }
2. Security and privacy considerations
2.1. Device access is powerful
When a website requests access to devices using requestDevice()
,
it gets the ability to access all GATT services mentioned in the call.
The UA MUST inform the user what capabilities these services give the website
before asking which devices to entrust to it.
If any services in the list aren’t known to the UA,
the UA MUST assume they give the site complete control over the device
and inform the user of this risk.
The UA MUST also allow the user to inspect what sites have access to what devices
and revoke these pairings.
The UA MUST NOT allow the user to pair entire classes of devices with a website. It is possible to construct a class of devices for which each individual device sends the same Bluetooth-level identifying information. UAs are not required to attempt to detect this sort of forgery and MAY let a user pair this pseudo-device with a website.
To help ensure that only the entity the user approved for access actually has access, this specification requires that only secure contexts can access Bluetooth devices.
2.2. Trusted servers can serve malicious code
This section is non-normative.
Even if the user trusts an origin, that origin’s servers or developers could be compromised, or the origin’s site could be vulnerable to XSS attacks. Either could lead to users granting malicious code access to valuable devices. Origins should define a Content Security Policy ([CSP3]) to reduce the risk of XSS attacks, but this doesn’t help with compromised servers or developers.
The ability to retrieve granted devices after a page reload, provided by § 3.1 Permission API Integration, makes this risk worse. Instead of having to get the user to grant access while the site is compromised, the attacker can take advantage of previously-granted devices if the user simply visits while the site is compromised. On the other hand, when sites can keep access to devices across page reloads, they don’t have to show as many permission prompts overall, making it more likely that users will pay attention to the prompts they do see.
2.3. Attacks on devices
This section is non-normative.
Communication from websites can break the security model of some devices, which assume they only receive messages from the trusted operating system of a remote device. Human Interface Devices are a prominent example, where allowing a website to communicate would allow that site to log keystrokes. This specification includes a GATT blocklist of such vulnerable services, characteristics, and descriptors to prevent websites from taking advantage of them.
We expect that many devices are vulnerable to unexpected data delivered to their radio. In the past, these devices had to be exploited one-by-one, but this API makes it plausible to conduct large-scale attacks. This specification takes several approaches to make such attacks more difficult:
- Pairing individual devices instead of device classes requires at least a user action before a device can be exploited.
-
Constraining access to GATT, as opposed to generic byte-stream access,
denies malicious websites access to most parsers on the device.
On the other hand, GATT’s Characteristic and Descriptor values are still byte arrays, which may be set to lengths and formats the device doesn’t expect. UAs are encouraged to validate these values when they can.
- This API never exposes Bluetooth addressing, data signing or encryption keys (Definition of Keys and Values) to websites. This makes it more difficult for a website to predict the bits that will be sent over the radio, which blocks packet-in-packet injection attacks. Unfortunately, this only works over encrypted links, which not all BLE devices are required to support.
UAs can also take further steps to protect their users:
- A web service may collect lists of malicious websites and vulnerable devices. UAs can deny malicious websites access to any device and any website access to vulnerable devices.
2.4. Bluetooth device identifiers
This section is non-normative.
Each Bluetooth BR/EDR device has a unique 48-bit MAC address known as the BD_ADDR. Each Bluetooth LE device has at least one of a Public Device Address and a Static Device Address. The Public Device Address is a MAC address. The Static Device Address may be regenerated on each restart. A BR/EDR/LE device will use the same value for the BD_ADDR and the Public Device Address (specified in the Read BD_ADDR Command).
An LE device may also have a unique, 128-bit Identity Resolving Key, which is sent to trusted devices during the bonding process. To avoid leaking a persistent identifier, an LE device may scan and advertise using a random Resolvable or Non-Resolvable Private Address instead of its Static or Public Address. These are regenerated periodically (approximately every 15 minutes), but a bonded device can check whether one of its stored IRKs matches any given Resolvable Private Address using the Resolvable Private Address Resolution Procedure.
Each Bluetooth device also has a human-readable Bluetooth Device Name. These aren’t guaranteed to be unique, but may well be, depending on the device type.
2.4.1. Identifiers for remote Bluetooth devices
This section is non-normative.
If a website can retrieve any of the persistent device IDs, these can be used, in combination with a large effort to catalog ambient devices, to discover a user’s location. A device ID can also be used to identify that a user who pairs two different websites with the same Bluetooth device is a single user. On the other hand, many GATT services are available that could be used to fingerprint a device, and a device can easily expose a custom GATT service to make this easier.
This specification suggests that the UA use different device IDs for a single device when its user doesn’t intend scripts to learn that it’s a single device, which makes it difficult for websites to abuse the device address like this. Device makers can still design their devices to help track users, but it takes work.
2.4.2. The UA’s Bluetooth address
This section is non-normative.
In BR/EDR mode, or in LE mode during active scanning without the Privacy Feature, the UA broadcasts its persistent ID to any nearby Bluetooth radio. This makes it easy to scatter hostile devices in an area and track the UA. As of 2014-08, few or no platforms document that they implement the Privacy Feature, so despite this spec recommending it, few UAs are likely to use it. This spec does require a user gesture for a website to trigger a scan, which reduces the frequency of scans some, but it would still be better for more platforms to expose the Privacy Feature.
2.5. Exposing Bluetooth availability
This section is non-normative.
navigator.bluetooth.
exposes whether a Bluetooth radio is available on the user’s system,
regardless of whether it is powered on or not.
Some users might consider this private,
although it’s hard to imagine the damage that would result from revealing it.
This information also increases the UA’s fingerprinting surface by a bit.
This function returns a getAvailability()
Promise
,
so UAs have the option of asking the user what value they want to return,
but we expect the increased risk to be small enough that
UAs will choose not to prompt.
3. Device Discovery
dictionary {
BluetoothDataFilterInit BufferSource ;
dataPrefix BufferSource ; };
mask dictionary {
BluetoothLEScanFilterInit sequence <BluetoothServiceUUID >services ;DOMString name ;DOMString namePrefix ; // Maps unsigned shorts to BluetoothDataFilters.object manufacturerData ; // Maps BluetoothServiceUUIDs to BluetoothDataFilters.object serviceData ; };dictionary {
RequestDeviceOptions sequence <BluetoothLEScanFilterInit >filters ;sequence <BluetoothServiceUUID >optionalServices = [];boolean acceptAllDevices =false ; }; [Exposed =Window ,SecureContext ]interface :
Bluetooth EventTarget {Promise <boolean >getAvailability ();attribute EventHandler ; [
onavailabilitychanged SameObject ]readonly attribute BluetoothDevice ?referringDevice ;Promise <BluetoothDevice >requestDevice (optional RequestDeviceOptions ); };
options Bluetooth includes BluetoothDeviceEventHandlers ;Bluetooth includes CharacteristicEventHandlers ;Bluetooth includes ServiceEventHandlers ;
Bluetooth
members getAvailability()
informs the page
whether Bluetooth is available at all.
An adapter that’s disabled through software should count as available.
Changes in availability,
for example when the user physically attaches or detaches an adapter,
are reported through the availabilitychanged
event.
referringDevice
gives access to
the device from which the user opened this page, if any.
For example, an Eddystone beacon
might advertise a URL, which the UA allows the user to open.
A BluetoothDevice
representing the beacon would be available
through navigator.bluetooth.
. referringDevice
requestDevice(options)
asks the user
to grant this origin access to a device
that matches any filter in options.
.
To match a filter, the device has to: filters
- support all the GATT service UUIDs
in the
services
list if that member is present, - have a name equal to
name
if that member is present, - have a name starting with
namePrefix
if that member is present, - advertise manufacturer specific data matching all of the key/value pairs in
manufacturerData
if that member is present, and - advertise service data matching all of the key/value pairs in
serviceData
if that member is present.
Both Manufacturer Specific Data and Service Data map a key to an array of bytes. BluetoothDataFilterInit
filters these arrays.
An array matches if it has a prefix such that prefix &
is equal to mask
. dataPrefix
& mask
Note that if a device changes its behavior significantly when it connects, for example by not advertising its identifying manufacturer data anymore and instead having the client discover some identifying GATT services, the website may need to include filters for both behaviors.
In rare cases,
a device may not advertise enough distinguishing information
to let a site filter out uninteresting devices.
In those cases, a site can set acceptAllDevices
to true
and omit all filters
.
This puts the burden of selecting the right device entirely on the site’s users.
If a site uses acceptAllDevices
,
it will only be able to use services listed in optionalServices
.
After the user selects a device to pair with this origin,
the origin is allowed to access any service whose UUID was listed
in the services
list
in any element of options.filters
or in options.
. optionalServices
This implies that if developers filter just by name,
they must use optionalServices
to get access to any services.
Say the UA is close to the following devices:
Device | Advertised Services |
---|---|
D1 | A, B, C, D |
D2 | A, B, E |
D3 | C, D |
D4 | E |
D5 | <none> |
If the website calls
navigator. bluetooth. requestDevice({ filters: [ { services: [ A, B]} ] });
the user will be shown a dialog containing devices D1 and D2. If the user selects D1, the website will not be able to access services C or D. If the user selects D2, the website will not be able to access service E.
On the other hand, if the website calls
navigator. bluetooth. requestDevice({ filters: [ { services: [ A, B]}, { services: [ C, D]} ] });
the dialog will contain devices D1, D2, and D3, and if the user selects D1, the website will be able to access services A, B, C, and D.
The optionalServices
list doesn’t add any devices
to the dialog the user sees,
but it does affect which services the website can use from the device the user picks.
navigator. bluetooth. requestDevice({ filters: [ { services: [ A, B]} ], optionalServices: [ E] });
Shows a dialog containing D1 and D2, but not D4, since D4 doesn’t contain the required services. If the user selects D2, unlike in the first example, the website will be able to access services A, B, and E.
The allowed services also apply if the device changes after the user grants access.
For example, if the user selects D1 in the previous requestDevice()
call,
and D1 later adds a new E service,
that will fire the serviceadded
event,
and the web page will be able to access service E.
Say the devices in the previous example also advertise names as follows:
Device | Advertised Device Name |
---|---|
D1 | First De… |
D2 | <none> |
D3 | Device Third |
D4 | Device Fourth |
D5 | Unique Name |
The following table shows which devices the user can select between
for several values of filters passed to navigator.bluetooth.requestDevice({filters: filters})
.
filters | Devices | Notes |
---|---|---|
| D5 | |
| D3, D4 | |
| <none> | D1 only advertises a prefix of its name, so trying to match its whole name fails. |
| D1, D5 | |
| D3, D5 |
Say the devices in the previous example also advertise manufacturer or service data as follows:
Device | Manufacturer Data | Service Data |
---|---|---|
D1 | 17: 01 02 03 | |
D2 | A: 01 02 03 |
The following table shows which devices the user can select between
for several values of filters passed to navigator.bluetooth.requestDevice({filters: filters})
.
filters | Devices |
---|---|
| D1 |
| D2 |
| D1, D2 |
| <none> |
| D1 |
| <none> |
| D1 |
| D1 |
| <none> |
Filters that either accept or reject all possible devices cause TypeError
s.
To accept all devices, use acceptAllDevices
instead.
Call | Notes |
---|---|
requestDevice | Invalid: An absent list of filters doesn’t accept any devices. |
requestDevice | Invalid: An empty list of filters doesn’t accept any devices. |
requestDevice | Invalid: An empty filter accepts all devices, and so isn’t allowed either. |
requestDevice | Valid: Explicitly accept all devices with acceptAllDevices .
|
requestDevice | Invalid: acceptAllDevices would override any filters .
|
requestDevice | Invalid: namePrefix , if present, must be non-empty to filter devices.
|
requestDevice | Invalid: manufacturerData , if present,
must be non-empty to filter devices.
|
requestDevice | Invalid: serviceData , if present,
must be non-empty to filter devices.
|
Instances of Bluetooth
are created with the internal slots described in the following table:
Internal Slot | Initial Value | Description (non-normative) |
---|---|---|
[[deviceInstanceMap]]
| An empty map from Bluetooth devices
to instances.
| Ensures only one BluetoothDevice instance represents each Bluetooth device inside a single global object.
|
[[attributeInstanceMap]]
| An empty map from Bluetooth cache entries to Promise s.
| The Promise s resolve to either BluetoothRemoteGATTService , BluetoothRemoteGATTCharacteristic , or BluetoothRemoteGATTDescriptor instances.
|
[[referringDevice]]
| null
| Set to a BluetoothDevice while initializing a new Document object if the Document was opened from the device.
|
Getting navigator.bluetooth.
must return referringDevice
[[referringDevice]]
.
Some UAs may allow the user
to cause a browsing context to navigate in response to a Bluetooth device. For example, if an Eddystone beacon
advertises a URL,
the UA may allow the user to navigate to this URL. If this happens, then as part of initializing a new Document
object,
the UA MUST run the following steps:
- Let referringDevice be the device that caused the navigation.
- Get the
BluetoothDevice
representing referringDevice insidenavigator.bluetooth
, and let referringDeviceObj be the result. -
If the previous step threw an exception, abort these steps.
Note: This means the UA didn’t infer that the user intended to grant the current realm access to referringDevice. For example, the user might have denied GATT access globally.
- Set
navigator.bluetooth.
to referringDeviceObj.[[referringDevice]]
A Bluetooth device device matches a filter filter if the following steps return match
:
- If
filter.
is present then, if device’s Bluetooth Device Name isn’t complete and equal toname
filter.name
, returnmismatch
. - If
filter.
is present then if device’s Bluetooth Device Name isn’t present or doesn’t start withnamePrefix
filter.namePrefix
, returnmismatch
. - For each uuid in
filter.
, if the UA has not received advertising data, an extended inquiry response, or a service discovery response indicating that the device supports a primary (vs included) service with UUID uuid, returnservices
mismatch
. - If
filter.
is present then for each manufacturerId inmanufacturerData
filter.manufacturerData.
, if device hasn’t advertised manufacturer specific data with a company identifier code that stringifies in base 10 to manufacturerId and with data that matches[[OwnPropertyKeys]]
()filter.
returnmanufacturerData
[manufacturerId]mismatch
. - If
filter.
is present then for each uuid inserviceData
filter.
, if device hasn’t advertised service data with a UUID whose 128-bit form is uuid and with data that matchesserviceData
.[[OwnPropertyKeys]]
()filter.
, returnserviceData
[manufacturerId]mismatch
. - Return
match
.
An array of bytes data matches a BluetoothDataFilterInit
filter if the following steps return match
.
Note: This algorithm assumes that filter has already been canonicalized.
- Let expectedPrefix be a copy of the bytes held by
filter.
.dataPrefix
- Let mask be a copy of the bytes held by
filter.
.mask
- If data has fewer bytes than expectedPrefix, return
mismatch
. - For each
1
bit in mask, if the corresponding bit in data is not equal to the corresponding bit in expectedPrefix, returnmismatch
. - Return
match
.
The list of Service UUIDs that a device advertises might not include all the UUIDs the device supports. The advertising data does specify whether this list is complete. If a website filters for a UUID that a nearby device supports but doesn’t advertise, that device might not be included in the list of devices presented to the user. The UA would need to connect to the device to discover the full list of supported services, which can impair radio performance and cause delays, so this spec doesn’t require it.
The
method,
when invoked, MUST return a new promise promise and run the following steps in parallel: requestDevice(options)
-
If
options.
is present andfilters
options.
isacceptAllDevices
true
, or ifoptions.
is not present andfilters
options.
isacceptAllDevices
false
, reject promise with aTypeError
and abort these steps.Note: This enforces that exactly one of
filters
or
is present.acceptAllDevices
:true - Request Bluetooth devices,
passing
options.
iffilters
options.
isacceptAllDevices
false
ornull
otherwise, and passingoptions.
, and let devices be the result.optionalServices
- If the previous step threw an exception, reject promise with that exception and abort these steps.
- If devices is an empty sequence, reject promise with a
NotFoundError
and abort these steps. - Resolve promise with
devices[0]
.
To request Bluetooth devices,
given a sequence of BluetoothLEScanFilterInit
s, filters,
which can be null
to represent that all devices can match,
and a sequence of BluetoothServiceUUID
s, optionalServices,
the UA MUST run the following steps:
Note: These steps can block, so uses of this algorithm must be in parallel.
Calls to this algorithm will eventually be able to request multiple devices, but for now it only ever returns a single one.
- If the algorithm is not triggered by user activation,
throw a
SecurityError
and abort these steps. -
In order to convert the arguments from service names and aliases to just UUIDs,
do the following sub-steps:
- If
filters !== null && filters.length === 0
, throw aTypeError
and abort these steps. - Let uuidFilters be a new
Array
and requiredServiceUUIDs be a newSet
. - If filters is
null
, then set requiredServiceUUIDs to the set of all UUIDs. -
If filters isn’t
null
, then for each filter in filters, do the following steps:- Let canonicalFilter be the result of canonicalizing filter.
- Append canonicalFilter to uuidFilters.
- Add the contents of
canonicalFilter.services
to requiredServiceUUIDs.
- Let optionalServiceUUIDs be
.Array.prototype.map
.call(optionalServices,BluetoothUUID.getService
) - If any of the
BluetoothUUID.getService()
calls threw an exception, throw that exception and abort these steps. - Remove from optionalServiceUUIDs any UUIDs that are blocklisted.
- If
-
Let descriptor be
{ name: "bluetooth" , filters: uuidFilters, optionalServices: optionalServiceUUIDs, acceptAllDevices: filters!== null , } -
Let state be descriptor’s permission state.
Note: state will be
"denied"
in non-secure contexts because"bluetooth"
doesn’t set the allowed in non-secure contexts flag. - If state is
"denied"
, return[]
and abort these steps. - If the UA can prove that no devices could possibly be found in the next step,
for example because there is no Bluetooth adapter with which to scan,
or because the filters can’t be matched by any possible advertising packet,
the UA MAY return
[]
and abort these steps. - Scan for devices with requiredServiceUUIDs as the set of Service UUIDs, and let scanResult be the result.
- If filters isn’t null, remove devices from scanResult if they do not match a filter in uuidFilters.
-
Even if scanResult is empty, prompt the user to choose one of the devices in scanResult,
associated with descriptor,
and let device be the result.
The UA MAY allow the user to select a nearby device that does not match uuidFilters.
The UA should show the user the human-readable name of each device. If this name is not available because, for example, the UA’s Bluetooth system doesn’t support privacy-enabled scans, the UA should allow the user to indicate interest and then perform a privacy-disabled scan to retrieve the name.
- If device is
"denied"
, return[]
and abort these steps. - Choosing a device probably indicates that
the user intends that device to appear in
the
allowedDevices
list of"bluetooth"
's extra permission data for at least the current settings object, for itsmayUseGATT
field to betrue
, and for all the services in the union of requiredServiceUUIDs and optionalServiceUUIDs to appear in itsallowedServices
list, in addition to any services that were already there. - The UA MAY populate the Bluetooth cache with all Services inside device. Ignore any errors from this step.
- Get the
BluetoothDevice
representing device inside the context object, propagating any exception, and let deviceObj be the result. - Return
[deviceObj]
.
The result of canonicalizing the BluetoothLEScanFilterInit
filter,
is the BluetoothLEScanFilterInit
returned from the following steps:
- If none of filter’s
members is present,
throw a
TypeError
and abort these steps. - Let canonicalizedFilter be
{}
. -
If
filter.
is present, do the following sub-steps:services
- If
filter.services.length === 0
, throw aTypeError
and abort these steps. - Let services be
.Array.prototype.map
.call(filter.services,BluetoothUUID.getService
) - If any of the
BluetoothUUID.getService()
calls threw an exception, throw that exception and abort these steps. - If any service in services is blocklisted,
throw a
SecurityError
and abort these steps. - Set
canonicalizedFilter.services
to services.
- If
-
If
filter.
is present, do the following sub-steps.name
-
If the UTF-8 encoding of
filter.name
is more than 248 bytes long, throw aTypeError
and abort these steps.248 is the maximum number of UTF-8 code units in a Bluetooth Device Name.
- Set
canonicalizedFilter.name
tofilter.name
.
-
If the UTF-8 encoding of
-
If
filter.
is present, do the following sub-steps.namePrefix
-
If
filter.namePrefix.length === 0
or if the UTF-8 encoding offilter.namePrefix
is more than 248 bytes long, throw aTypeError
and abort these steps.248 is the maximum number of UTF-8 code units in a Bluetooth Device Name.
- Set
canonicalizedFilter.namePrefix
tofilter.namePrefix
.
-
If
- Set
canonicalizedFilter.manufacturerData
to{}
. -
If
filter.
is present, do the following sub-steps for each key inmanufacturerData
filter.manufacturerData.
. If there are no such keys, throw a[[OwnPropertyKeys]]
()TypeError
and abort these steps.- Let manufacturerId be CanonicalNumericIndexString(key).
- If manufacturerId is
undefined
or-0
, or IsInteger(manufacturerId) isfalse
, or manufacturerId is outside the range from 0–65535 inclusive, throw aTypeError
and abort these steps. - Let dataFilter be
filter.manufacturerData[manufacturerId]
, converted to an IDL value of typeBluetoothDataFilterInit
. If this conversion throws an exception, propagate it and abort these steps. - Let canonicalizedDataFilter be the result of canonicalizing dataFilter, converted to an ECMAScript value. If this throws an exception, propagate that exception and abort these steps.
- Call CreateDataProperty(canonicalizedFilter.manufacturerData, key, canonicalizedDataFilter).
- Set
canonicalizedFilter.serviceData
to{}
. -
If
filter.
is present, do the following sub-steps for each key inserviceData
filter.serviceData.
. If there are no such keys, throw a[[OwnPropertyKeys]]
()TypeError
and abort these steps.- Let serviceName be CanonicalNumericIndexString(key).
- If serviceName is
undefined
, set serviceName to key. - Let service be
.BluetoothUUID.getService
(serviceName) - If the previous step threw an exception, throw that exception and abort these steps.
- If service is blocklisted,
throw a
SecurityError
and abort these steps. - Let dataFilter be
filter.serviceData[service]
, converted to an IDL value of typeBluetoothDataFilterInit
. If this conversion throws an exception, propagate it and abort these steps. - Let canonicalizedDataFilter be the result of canonicalizing dataFilter, converted to an ECMAScript value. If this throws an exception, propagate that exception and abort these steps.
- Call CreateDataProperty(canonicalizedFilter.serviceData, service, canonicalizedDataFilter).
- Return canonicalizedFilter.
The result of canonicalizing the BluetoothDataFilterInit
filter,
is the BluetoothDataFilterInit
returned from the following steps:
- If
filter.
is present, let dataPrefix be a copy of the bytes held bydataPrefix
filter.dataPrefix
. Otherwise, let dataPrefix be an empty sequence of bytes. - If
filter.
is present, let mask be a copy of the bytes held bymask
filter.mask
. Otherwise, let mask be a sequence of0xFF
bytes the same length as dataPrefix. - If mask is not the same length as dataPrefix,
throw a
TypeError
and abort these steps. - Return
{dataPrefix: new Uint8Array(|dataPrefix|), mask: new Uint8Array(|mask|)}
.
To scan for devices with an optional set of Service UUIDs, defaulting to the set of all UUIDs, the UA MUST perform the following steps:
- If the UA has scanned for devices recently TODO: Nail down the amount of time. with a set of UUIDs that was a superset of the UUIDs for the current scan, then the UA MAY return the result of that scan and abort these steps.
- Let nearbyDevices be a set of Bluetooth devices, initially equal to the set of devices that are connected (have an ATT Bearer) to the UA.
-
If the UA supports the LE transport, perform the General Discovery Procedure,
except that the UA may include devices that have no Discoverable Mode flag set,
and add the discovered Bluetooth devices to nearbyDevices.
The UA SHOULD enable the Privacy Feature.
Both passive scanning and the Privacy Feature avoid leaking the unique, immutable device ID. We ought to require UAs to use either one, but none of the OS APIs appear to expose either. Bluetooth also makes it hard to use passive scanning since it doesn’t require Central devices to support the Observation Procedure.
-
If the UA supports the BR/EDR transport, perform the Device Discovery Procedure and add the discovered Bluetooth devices to nearbyDevices.
All forms of BR/EDR inquiry/discovery appear to leak the unique, immutable device address.
- Let result be a set of Bluetooth devices, initially empty.
-
For each Bluetooth device device in nearbyDevices,
do the following sub-steps:
- If device’s supported physical transports include LE and its Bluetooth Device Name is partial or absent, the UA SHOULD perform the Name Discovery Procedure to acquire a complete name.
-
If device’s advertised Service UUIDs have a non-empty intersection with the set of Service UUIDs,
add device to result and abort these sub-steps.
For BR/EDR devices, there is no way to distinguish GATT from non-GATT services in the Extended Inquiry Response. If a site filters to the UUID of a non-GATT service, the user may be able to select a device for the result of
requestDevice
that this API provides no way to interact with. -
The UA MAY connect to device and populate the Bluetooth cache with all Services whose UUIDs are in the set of Service UUIDs.
If device’s supported physical transports include BR/EDR,
then in addition to the standard GATT procedures,
the UA MAY use the Service Discovery Protocol (Searching for Services)
when populating the cache.
Connecting to every nearby device to discover services costs power and can slow down other use of the Bluetooth radio. UAs should only discover extra services on a device if they have some reason to expect that device to be interesting.
UAs should also help developers avoid relying on this extra discovery behavior. For example, say a developer has previously connected to a device, so the UA knows the device’s full set of supported services. If this developer then filters using a non-advertised UUID, the dialog they see may include this device, even if the filter would likely exclude the device on users' machines. The UA could provide a developer option to warn when this happens or to include only advertised services in matching filters.
- If the Bluetooth cache contains known-present Services inside device with UUIDs in the set of Service UUIDs, the UA MAY add device to result.
- Return result from the scan.
We need a way for a site to register to receive an event when an interesting device comes within range.
3.1. Permission API Integration
The [permissions] API provides a uniform way for websites to request permissions from users and query which permissions they have.
Sites can use navigator
as an alternate spelling of request
navigator
. requestDevice
navigator. permissions. request({ name: "bluetooth" , filters: [{ services: [ 'heart_rate' ], }] }). then( result=> { if ( result. devices. length>= 1 ) { return result. devices[ 0 ]; } else { throw new DOMException( "Chooser cancelled" , "NotFoundError" ); } }). then( device=> { sessionStorage. lastDevice= device. id; });
Once a site has been granted access to a set of devices,
it can use navigator
to retrieve those devices after a reload. query
navigator. permissions. query({ name: "bluetooth" , deviceId: sessionStorage. lastDevice, }). then( result=> { if ( result. devices. length== 1 ) { return result. devices[ 0 ]; } else { throw new DOMException( "Lost permission" , "NotFoundError" ); } }). then(...);
The "bluetooth"
powerful feature’s
permission-related algorithms and types
are defined as follows:
- permission descriptor type
-
dictionary
:BluetoothPermissionDescriptor PermissionDescriptor {DOMString
; // These match RequestDeviceOptions.deviceId sequence <BluetoothLEScanFilterInit >
;filters sequence <BluetoothServiceUUID >
= [];optionalServices boolean
=acceptAllDevices false ; }; - extra permission data type
-
BluetoothPermissionData
, defined as:dictionary
{AllowedBluetoothDevice required DOMString
;deviceId required boolean
; // An allowedServices of "all" means all services are allowed.mayUseGATT required (DOMString or sequence <UUID >)
; };allowedServices dictionary
{BluetoothPermissionData required sequence <AllowedBluetoothDevice >
; };allowedDevices AllowedBluetoothDevice
instances have an internal slot[[device]]
that holds a Bluetooth device. - extra permission data constraints
-
Distinct elements of
allowedDevices
must have different[[device]]
s and differentdeviceId
s.If
mayUseGATT
isfalse
,allowedServices
must be[]
.A
deviceId
allows a site to track that aBluetoothDevice
instance seen at one time represents the same device as anotherBluetoothDevice
instance seen at another time, possibly in a different realm. UAs should consider whether their user intends that tracking to happen or not-happen when returning"bluetooth"
's extra permission data.For example, users generally don’t intend two different origins to know that they’re interacting with the same device, and they generally don’t intend unique identifiers to persist after they’ve cleared an origin’s cookies.
- permission result type
-
[
Exposed =Window ]interface
:BluetoothPermissionResult PermissionStatus {attribute FrozenArray <BluetoothDevice >
; };devices - permission request algorithm
-
To request the "bluetooth" permission with a
BluetoothPermissionDescriptor
options and aBluetoothPermissionResult
status, the UA MUST run the following steps:-
If
options.
is present andfilters
options.
isacceptAllDevices
true
, or ifoptions.
is not present andfilters
options.
isacceptAllDevices
false
, throw aTypeError
.Note: This enforces that exactly one of
filters
or
is present.acceptAllDevices
:true - Request Bluetooth devices,
passing
options.
iffilters
options.
isacceptAllDevices
false
ornull
otherwise, and passingoptions.
, propagating any exception, and let devices be the result.optionalServices
- Set
status.devices
to a newFrozenArray
whose contents are the elements of devices.
-
If
- permission query algorithm
-
To query the "bluetooth" permission with
a
BluetoothPermissionDescriptor
desc and aBluetoothPermissionResult
status, the UA must:- Let global be the relevant global object for status.
- Set
status.
to desc’s permission state.state
- If
status.
isstate
"denied"
, setstatus.devices
to an emptyFrozenArray
and abort these steps. - Let matchingDevices be a new
Array
. - Let data, a
BluetoothPermissionData
, be"bluetooth"
's extra permission data for the current settings object. -
For each allowedDevice in
data.allowedDevices
, run the following sub-steps:- If
desc.deviceId
is set andallowedDevice.deviceId != desc.deviceId
, continue to the next allowedDevice. -
If
desc.filters
is set, do the following sub-steps:- Replace each filter in
desc.filters
with the result of canonicalizing it. If any of these canonicalizations throws an error, return that error and abort these steps. - If
allowedDevice.
does not match a filter in[[device]]
desc.filters
, continue to the next allowedDevice.
- Replace each filter in
- Get the
BluetoothDevice
representingallowedDevice.
within[[device]]
global.navigator.bluetooth
, and add the result to matchingDevices.
Note: The
desc.optionalServices
field does not affect the result. - If
- Set
status.devices
to a newFrozenArray
whose contents are matchingDevices.
- permission revocation algorithm
-
To revoke Bluetooth access to devices the user no longer intends to expose, the UA MUST run the following steps:
- Let data, a
BluetoothPermissionData
, be"bluetooth"
's extra permission data for the current settings object. -
For each
BluetoothDevice
instance deviceObj in the current realm, run the following sub-steps:-
If there is an
AllowedBluetoothDevice
allowedDevice indata.
such that:allowedDevices
-
allowedDevice.
is the same device as[[device]]
deviceObj.
, and[[representedDevice]]
-
allowedDevice.
,deviceId
=== deviceObj.id
deviceObj.
to be[[allowedServices]]
allowedDevice.
, and continue to the next deviceObj.allowedServices
-
- Otherwise, detach deviceObj from its device by running the remaining steps.
-
Call
deviceObj.gatt.
.disconnect()
Note: This fires a
gattserverdisconnected
event at deviceObj. - Set
deviceObj.
to[[representedDevice]]
null
.
-
If there is an
- Let data, a
3.2. Overall Bluetooth availability
The UA may be running on a computer that has no Bluetooth radio. requestDevice()
handles this by failing to discover any devices,
which results in a NotFoundError
,
but websites may be able to handle it more gracefully.
To show Bluetooth UI only to users who have a Bluetooth adapter:
let bluetoothUI= document. querySelector( '#bluetoothUI' ); navigator. bluetooth. getAvailability() . then( isAvailable=> { bluetoothUI. hidden= ! isAvailable; }); navigator. bluetooth. addEventListener( ' availabilitychanged ' , e=> { bluetoothUI. hidden= ! e. value; });
The
method,
when invoked, MUST return a new promise promise and run the following steps in parallel: getAvailability()
- If the user has configured the UA to return a particular answer from this function for the current origin, queue a task to resolve promise with the configured answer, and abort these steps.
- If the UA is running on a system that has a Bluetooth radio queue a task to resolve promise with
true
regardless of the powered state of the Bluetooth radio. - Otherwise, queue a task to resolve promise with
false
.
Note: the promise is resolved in parallel to let the UA call out to other systems to determine whether Bluetooth is available.
If the UA becomes able or unable to use Bluetooth,
for example because a radio was physically attached or detached,
or the user has changed
their configuration for
the answer returned from getAvailability()
,
the UA must queue a task on
each global object global’s responsible event loop to run the following steps:
- Let oldAvailability be
the value
getAvailability()
would have returned before the change. - Let newAvailability be
the value
getAvailability()
would return after the change. - If oldAvailability is not the same as newAvailability, fire an event named
availabilitychanged
using theValueEvent
interface atglobal.navigator.bluetooth
with itsvalue
attribute initialized to newAvailability.
[Exposed =Window ,(
Constructor DOMString ,
type optional ValueEventInit ),
initDict SecureContext ]interface :
ValueEvent Event {readonly attribute any value ; };dictionary :
ValueEventInit EventInit {any =
value null ; };
ValueEvent
instances are constructed
as specified in DOM Standard §constructing-events.
The value
attribute
must return the value it was initialized to.
Such a generic event type belongs in [HTML] or [DOM], not here.
4. Device Representation
The UA needs to track Bluetooth device properties at several levels: globally, per origin, and per global object.
4.1. Global Bluetooth device properties
The physical Bluetooth device may be guaranteed to have some properties that the UA may not have received. Those properties are described as optional here.
A Bluetooth device has the following properties. Optional properties are not present, and sequence and map properties are empty, unless/until described otherwise. Other properties have a default specified or are specified when a device is introduced.
- A set of supported physical transports, including one or both of BR/EDR and LE. This set will generally be filled based on the transports over which the device was discovered and the Flags Data Type in the Advertising Data or Extended Inquiry Response.
- One or more of several kinds of 48-bit address: a Public Bluetooth Address, a (random) Static Address, and a resolvable or non-resolvable Private Address.
- An optional 128-bit Identity Resolving Key.
- An optional partial or complete Bluetooth Device Name. A device has a partial name when the Shortened Local Name AD data was received, but the full name hasn’t been read yet. The Bluetooth Device Name is encoded as UTF-8 and converted to a DOMString using the utf-8 decode without BOM algorithm.
- An optional ATT Bearer, over which all GATT communication happens. The ATT Bearer is created by procedures described in "Connection Establishment" under GAP Interoperability Requirements. It is disconnected in ways [BLUETOOTH42] isn’t entirely clear about.
- A list of advertised Service UUIDs from the Advertising Data or Extended Inquiry Response.
- A hierarchy of GATT Attributes.
The UA SHOULD determine that two Bluetooth devices are the same Bluetooth device if and only if they have the same Public Bluetooth Address, Static Address, Private Address, or Identity Resolving Key, or if the Resolvable Private Address Resolution Procedure succeeds using one device’s IRK and the other’s Resolvable Private Address. However, because platform APIs don’t document how they determine device identity, the UA MAY use another procedure.
4.2. BluetoothDevice
A BluetoothDevice
instance represents a Bluetooth device for a particular global object (or, equivalently, for a particular Realm or Bluetooth
instance).
[Exposed =Window ,SecureContext ]interface BluetoothDevice :EventTarget {readonly attribute DOMString id ;readonly attribute DOMString ?name ;readonly attribute BluetoothRemoteGATTServer ?gatt ;Promise <void >watchAdvertisements ();void unwatchAdvertisements ();readonly attribute boolean watchingAdvertisements ; };BluetoothDevice includes BluetoothDeviceEventHandlers ;BluetoothDevice includes CharacteristicEventHandlers ;BluetoothDevice includes ServiceEventHandlers ;
BluetoothDevice
attributes id
uniquely identifies a device to the extent that
the UA can determine that two Bluetooth connections are to the same device
and to the extent that
the user wants to expose that fact to script.
name
is the human-readable name of the device.
gatt
provides a way to interact with this device’s GATT server
if the site has permission to do so.
watchingAdvertisements
is true if
the UA is currently scanning for advertisements from this device
and firing events for them.
Instances of BluetoothDevice
are created with the internal slots described in the following table:
Internal Slot | Initial Value | Description (non-normative) |
---|---|---|
[[context]]
| <always set in prose> | The Bluetooth object that returned this BluetoothDevice .
|
[[representedDevice]]
| <always set in prose> | The Bluetooth device this object represents,
or null if access has been revoked.
|
[[gatt]]
| a new BluetoothRemoteGATTServer instance with
its device attribute initialized to this and its connected attribute initialized to false .
| Does not change. |
[[allowedServices]]
| <always set in prose> | This device’s allowedServices list for this origin
or "all" if all services are allowed.
For example, a UA may grant an origin access to all services on
a referringDevice that advertised a URL on that origin.
|
To get the BluetoothDevice
representing a Bluetooth device device inside a Bluetooth
instance context,
the UA MUST run the following steps:
- Let data, a
BluetoothPermissionData
, be"bluetooth"
's extra permission data for the current settings object. - Find the allowedDevice in
data.
withallowedDevices
allowedDevice.
the same device as device. If there is no such object, throw a[[device]]
SecurityError
and abort these steps. -
If there is no key in context.
[[deviceInstanceMap]]
that is the same device as device, run the following sub-steps:- Let result be a new instance of
BluetoothDevice
. - Initialize all of result’s optional fields to
null
. - Initialize
result.
to context.[[context]]
- Initialize
result.
to device.[[representedDevice]]
- Initialize
result.id
toallowedDevice.
, and initializedeviceId
result.
to[[allowedServices]]
allowedDevice.
.allowedServices
- If device has a partial or complete Bluetooth Device Name,
set
result.name
to that string. - Initialize
result.watchingAdvertisements
tofalse
. - Add a mapping from device to result in context.
[[deviceInstanceMap]]
.
- Let result be a new instance of
- Return the value in context.
[[deviceInstanceMap]]
whose key is the same device as device.
Getting the
attribute
MUST perform the following steps: gatt
- If
"bluetooth"
's extra permission data forthis
's relevant settings object has anAllowedBluetoothDevice
allowedDevice in itsallowedDevices
list withallowedDevice.
the same device as[[device]]
this.
and[[representedDevice]]
allowedDevice.
equal tomayUseGATT
true
, returnthis.
.[[gatt]]
- Otherwise, return
null
.
Scanning costs power,
so websites should avoid watching for advertisements unnecessarily,
and should call unwatchAdvertisements()
to stop using power as soon as possible.
The
method,
when invoked,
MUST return a new promise promise and
run the following steps in parallel: watchAdvertisements()
- Ensure that the UA is scanning for this device’s advertisements. The UA SHOULD NOT filter out "duplicate" advertisements for the same device.
-
If the UA fails to enable scanning, reject promise with one of the following errors,
and abort these steps:
- The UA doesn’t support scanning for advertisements
NotSupportedError
- Bluetooth is turned off
InvalidStateError
- Other reasons
UnknownError
-
Queue a task to perform the following steps:
- Set
this.
towatchingAdvertisements
true
. - Resolve promise with
undefined
.
- Set
The
method,
when invoked,
MUST run the following steps: unwatchAdvertisements()
- Set
this.
towatchingAdvertisements
false
. - If no more
BluetoothDevice
s in the whole UA havewatchingAdvertisements
set totrue
, the UA SHOULD stop scanning for advertisements. Otherwise, if no moreBluetoothDevice
s representing the same device asthis
havewatchingAdvertisements
set totrue
, the UA SHOULD reconfigure the scan to avoid receiving reports for this device.
4.2.1. Responding to Advertising Events
When an advertising event arrives for a BluetoothDevice
with watchingAdvertisements
set,
the UA delivers an "advertisementreceived
" event.
[Exposed =Window ,SecureContext ]interface BluetoothManufacturerDataMap {readonly maplike <unsigned short ,DataView >; }; [Exposed =Window ,SecureContext ]interface BluetoothServiceDataMap {readonly maplike <UUID ,DataView >; }; [Exposed =Window ,Constructor (DOMString ,
type BluetoothAdvertisingEventInit ),
init SecureContext ]interface :
BluetoothAdvertisingEvent Event { [SameObject ]readonly attribute BluetoothDevice device ;readonly attribute FrozenArray <UUID >uuids ;readonly attribute DOMString ?name ;readonly attribute unsigned short ?appearance ;readonly attribute byte ?txPower ;readonly attribute byte ?rssi ; [SameObject ]readonly attribute BluetoothManufacturerDataMap manufacturerData ; [SameObject ]readonly attribute BluetoothServiceDataMap serviceData ; };dictionary :
BluetoothAdvertisingEventInit EventInit {required BluetoothDevice ;
device sequence <(DOMString or unsigned long )>;
uuids DOMString ;
name unsigned short ;
appearance byte ;
txPower byte ;
rssi BluetoothManufacturerDataMap ;
manufacturerData BluetoothServiceDataMap ; };
serviceData
BluetoothAdvertisingEvent
attributes device
is the BluetoothDevice
that sent this advertisement.
uuids
lists the Service UUIDs that
this advertisement says device
's GATT server supports.
name
is device
's local name, or a prefix of it.
appearance
is an Appearance, one of the values defined by
the org.bluetooth.characteristic.gap.appearance
characteristic.
txPower
is
the transmission power at which the device is broadcasting, measured in dBm.
This is used to compute the path loss as this.txPower - this.rssi
.
rssi
is
the power at which the advertisement was received, measured in dBm.
This is used to compute the path loss as this.txPower - this.rssi
.
manufacturerData
maps unsigned short
Company Identifier Codes
to DataView
s.
To retrieve a device and read the iBeacon data out of it,
a developer could use the following code.
Note that this API currently doesn’t provide a way
to request devices with certain manufacturer data,
so the iBeacon will need to rotate its advertisements to include a known service
in order for users to select this device in the requestDevice
dialog.
var known_service= "A service in the iBeacon’s GATT server" ; return navigator. bluetooth. requestDevice({ filters: [{ services: [ known_service]}] }). then( device=> { device. watchAdvertisements(); device. addEventListener( 'advertisementreceived' , interpretIBeacon); }); function interpretIBeacon( event) { var rssi= event. rssi; var appleData= event. manufacturerData. get( 0x004C ); if ( appleData. byteLength!= 23 || appleData. getUint16( 0 , false ) !== 0x0215 ) { console. log({ isBeacon: false }); } var uuidArray= new Uint8Array( appleData. buffer, 2 , 16 ); var major= appleData. getUint16( 18 , false ); var minor= appleData. getUint16( 20 , false ); var txPowerAt1m= - appleData. getInt8( 22 ); console. log({ isBeacon: true , uuidArray, major, minor, pathLossVs1m: txPowerAt1m- rssi}); });
The format of iBeacon advertisements was derived from How do iBeacons work? by Adam Warski.
When the UA receives an advertising event (consisting of an advertising packet and an optional scan response), it MUST run the following steps:
- Let device be the Bluetooth device that sent the advertising event.
-
For each
BluetoothDevice
deviceObj in the UA such that device is the same device asdeviceObj.
, queue a task on deviceObj’s relevant settings object’s responsible event loop to do the following sub-steps:[[representedDevice]]
- If
deviceObj.
iswatchingAdvertisements
false
, abort these sub-steps. - Fire an
advertisementreceived
event for the advertising event at deviceObj.
- If
To fire an advertisementreceived
event for an advertising event adv at a BluetoothDevice
deviceObj,
the UA MUST perform the following steps:
-
Let event be
{ bubbles: true , device: deviceObj, uuids: [], manufacturerData: new Map(), serviceData: new Map() } - If the received signal strength is available
for any packet in adv,
set
event.rssi
to this signal strength in dBm. -
For each AD structure in adv’s advertising packet and scan response,
select from the following steps depending on the AD type:
- Incomplete List of 16-bit Service UUIDs
- Complete List of 16-bit Service UUIDs
- Incomplete List of 32-bit Service UUIDs
- Complete List of 32-bit Service UUIDs
- Incomplete List of 128-bit Service UUIDs
- Complete List of 128-bit Service UUIDs
- Complete List of 16-bit Service UUIDs
- Append the listed UUIDs to
event.uuids
. - Shortened Local Name
- Complete Local Name
-
UTF-8 decode without BOM the AD data and
set
event.name
to the result.Note: We don’t expose whether the name is complete because existing APIs require reading the raw advertisement to get this information, and we want more evidence that it’s useful before adding a field to the API.
- Manufacturer Specific Data
- Add to
event.manufacturerData
a mapping from the 16-bit Company Identifier Code to anArrayBuffer
containing the manufacturer-specific data. - TX Power Level
- Set
event.txPower
to the AD data. - Service Data - 16 bit UUID
- Service Data - 32 bit UUID
- Service Data - 128 bit UUID
- Service Data - 32 bit UUID
- Add to
event.serviceData
a mapping from the UUID to anArrayBuffer
containing the service data. - Appearance
- Set
event.appearance
to the AD data. - Otherwise
- Skip to the next AD structure.
- Incomplete List of 16-bit Service UUIDs
- Fire an event initialized as
new
, with itsBluetoothAdvertisingEvent
("advertisementreceived
", event)isTrusted
attribute initialized totrue
, at deviceObj.
All fields in BluetoothAdvertisingEvent
return
the last value they were initialized or set to.
The BluetoothAdvertisingEvent(type, init)
constructor MUST perform the following steps:
- Let event be the result of running the steps from DOM §2.5 Constructing events except for the
uuids
,manufacturerData
, andserviceData
members. - If
init.uuids
is set, initializeevent.uuids
to a newFrozenArray
containing the elements ofinit.uuids.map(
. Otherwise initializeBluetoothUUID.getService
)event.uuids
to an emptyFrozenArray
. -
For each mapping in
init.manufacturerData
:- Let code be the key converted to an
unsigned short
. - Let value be the value.
- If value is not a
BufferSource
, throw aTypeError
. - Let bytes be a new read only ArrayBuffer containing a copy of the bytes held by value.
- Add a mapping from code to
new DataView(bytes)
inevent.manufacturerData.
.[[BackingMap]]
- Let code be the key converted to an
-
For each mapping in
init.serviceData
:- Let key be the key.
- Let service be the result of calling
BluetoothUUID.
getService
(key). - Let value be the value.
- Set value is not a
BufferSource
, throw aTypeError
. - Let bytes be a new read only ArrayBuffer containing a copy of the bytes held by value.
- Add a mapping from service to
new DataView(bytes)
inevent.serviceData.
.[[BackingMap]]
- Return event.
4.2.1.1. BluetoothManufacturerDataMap
Instances of BluetoothManufacturerDataMap
have a [[BackingMap]]
slot because they are maplike, which maps manufacturer codes to
the manufacturer’s data, converted to DataView
s.
4.2.1.2. BluetoothServiceDataMap
Instances of BluetoothServiceDataMap
have a [[BackingMap]]
slot because they are maplike, which maps service UUIDs to the
service’s data, converted to DataView
s.
5. GATT Interaction
5.1. GATT Information Model
The GATT Profile Hierarchy describes how a GATT Server contains a hierarchy of Profiles, Primary Services, Included Services, Characteristics, and Descriptors.
Profiles are purely logical: the specification of a Profile describes the expected interactions between the other GATT entities the Profile contains, but it’s impossible to query which Profiles a device supports.
GATT Clients can discover and interact with the Services, Characteristics, and Descriptors on a device using a set of GATT procedures. This spec refers to Services, Characteristics, and Descriptors collectively as Attributes. All Attributes have a type that’s identified by a UUID. Each Attribute also has a 16-bit Attribute Handle that distinguishes it from other Attributes of the same type on the same GATT Server. Attributes are notionally ordered within their GATT Server by their Attribute Handle, but while platform interfaces provide attributes in some order, they do not guarantee that it’s consistent with the Attribute Handle order.
A Service contains a collection of Included Services and Characteristics. The Included Services are references to other Services, and a single Service can be included by more than one other Service. Services are known as Primary Services if they appear directly under the GATT Server, and Secondary Services if they’re only included by other Services, but Primary Services can also be included.
A Characteristic contains a value, which is an array of bytes, and a collection of Descriptors. Depending on the properties of the Characteristic, a GATT Client can read or write its value, or register to be notified when the value changes.
Finally, a Descriptor contains a value (again an array of bytes) that describes or configures its Characteristic.
5.1.1. Persistence across connections
The Bluetooth Attribute Caching system allows bonded clients
to save references to attributes from one connection to the next.
Web Bluetooth treats websites as not bonded to devices they have permission to access: BluetoothRemoteGATTService
, BluetoothRemoteGATTCharacteristic
,
and BluetoothRemoteGATTDescriptor
objects
become invalid on disconnection,
and the site must retrieved them again when it re-connects.
5.1.2. The Bluetooth cache
The UA MUST maintain a Bluetooth cache of the hierarchy of Services, Characteristics, and Descriptors
it has discovered on a device.
The UA MAY share this cache between multiple origins accessing the same device.
Each potential entry in the cache is either known-present, known-absent, or unknown.
The cache MUST NOT contain two entries that are for the same attribute.
Each known-present entry in the cache is associated with an optional Promise<
, BluetoothRemoteGATTService
>Promise<
,
or BluetoothRemoteGATTCharacteristic
>Promise<
instance
for each BluetoothRemoteGATTDescriptor
>Bluetooth
instance.
For example, if a user calls the serviceA.getCharacteristic(uuid1)
function
with an initially empty Bluetooth cache,
the UA uses the Discover Characteristics by UUID procedure
to fill the needed cache entries,
and the UA ends the procedure early because
it only needs one Characteristic to fulfil the returned Promise
,
then the first Characteristic with UUID uuid1
inside serviceA
is known-present,
and any subsequent Characteristics with that UUID remain unknown.
If the user later calls serviceA.getCharacteristics(uuid1)
,
the UA needs to resume or restart the Discover Characteristics by UUID procedure.
If it turns out that serviceA
only has one Characteristic with UUID uuid1
,
then the subsequent Characteristics become known-absent.
The known-present entries in the Bluetooth cache are ordered: Primary Services appear in a particular order within a device, Included Services and Characteristics appear in a particular order within Services, and Descriptors appear in a particular order within Characteristics. The order SHOULD match the order of Attribute Handles on the device, but UAs MAY use another order if the device’s order isn’t available.
To populate the Bluetooth cache with entries matching some description, the UA MUST run the following steps. Note that these steps can block, so uses of this algorithm must be in parallel.
- Attempt to make all matching entries in the cache either known-present or known-absent, using any sequence of GATT procedures that [BLUETOOTH42] specifies will return enough information. Handle errors as described in § 5.7 Error handling.
- If the previous step returns an error, return that error from this algorithm.
To query the Bluetooth cache in
a BluetoothDevice
instance deviceObj for entries matching some description,
the UA MUST return a deviceObj.gatt
-connection-checking wrapper around a new promise promise and run the following steps in parallel:
- Populate the Bluetooth cache with entries matching the description.
- If the previous step returns an error, reject promise with that error and abort these steps.
- Let entries be the sequence of known-present cache entries matching the description.
- Let context be
deviceObj.
.[[context]]
- Let result be a new sequence.
-
For each entry in entries:
- If entry has no associated
Promise<BluetoothGATT*>
instance in context.[[attributeInstanceMap]]
, create aBluetoothRemoteGATTService
representing entry, create aBluetoothRemoteGATTCharacteristic
representing entry, or create aBluetoothRemoteGATTDescriptor
representing entry, depending on whether entry is a Service, Characteristic, or Descriptor, and add a mapping from entry to the resultingPromise
in context.[[attributeInstanceMap]]
. - Append to result the
Promise<BluetoothGATT*>
instance associated with entry in context.[[attributeInstanceMap]]
.
- If entry has no associated
- Resolve promise with the result of waiting for all elements of result.
Represented(obj: Device or GATT Attribute) returns, depending on the type of obj:
5.1.3. Navigating the Bluetooth Hierarchy
To GetGATTChildren(attribute: GATT Attribute,
single: boolean,
uuidCanonicalizer: function,
uuid: optional (DOMString or unsigned int)
,
allowedUuids: optional ("all" or Array<DOMString>)
,
child type: GATT declaration type),
the UA MUST perform the following steps:
- If uuid is present, set it to uuidCanonicalizer(uuid). If uuidCanonicalizer threw an exception, return a promise rejected with that exception and abort these steps.
- If uuid is present and is blocklisted,
return a promise rejected with a
SecurityError
and abort these steps. -
Let deviceObj be, depending on the type of attribute:
BluetoothDevice
attribute
BluetoothRemoteGATTService
attribute.
device
BluetoothRemoteGATTCharacteristic
attribute.
service
.device
- If
deviceObj.gatt.
isconnected
false
, return a promise rejected with with aNetworkError
and abort these steps. -
If Represented(attribute) is
null
, return a promise rejected with anInvalidStateError
and abort these steps.Note: This happens when a Service or Characteristic is removed from the device or invalidated by a disconnection, and then its object is used again.
-
Query the Bluetooth cache in
deviceObj
for entries that:- are within Represented(attribute),
- have a type described by child type,
- have a UUID that is not blocklisted,
- if uuid is present, have a UUID of uuid,
- if allowedUuids is present and not
"all"
, have a UUID in allowedUuids, and - if the single flag is set, are the first of these.
-
Return the result of transforming promise with a fulfillment handler that:
- If its argument is empty, throws a
NotFoundError
, - Otherwise, if the single flag is set, returns the first (only) element of its argument.
- Otherwise, returns its argument.
- If its argument is empty, throws a
5.1.4. Identifying Services, Characteristics, and Descriptors
When checking whether two Services, Characteristics, or Descriptors a and b are the same attribute, the UA SHOULD determine that they are the same if a and b are inside the same device and have the same Attribute Handle, but MAY use any algorithm it wants with the constraint that a and b MUST NOT be considered the same attribute if they fit any of the following conditions:
- They are not both Services, both Characteristics, or both Descriptors.
- They are both Services, but are not both primary or both secondary services.
- They have different UUIDs.
- Their parent Devices aren’t the same device or their parent Services or Characteristics aren’t the same attribute.
This definition is loose because platform APIs expose their own notion of identity without documenting whether it’s based on Attribute Handle equality.
For two Javascript objects x and y representing Services, Characteristics, or Descriptors, x === y
returns
whether the objects represent the same attribute,
because of how the query the Bluetooth cache algorithm
creates and caches new objects.
5.2. BluetoothRemoteGATTServer
BluetoothRemoteGATTServer
represents a GATT Server on a remote device.
[Exposed =Window ,SecureContext ]interface BluetoothRemoteGATTServer { [SameObject ]readonly attribute BluetoothDevice device ;readonly attribute boolean connected ;Promise <BluetoothRemoteGATTServer >connect ();void disconnect ();Promise <BluetoothRemoteGATTService >getPrimaryService (BluetoothServiceUUID );
service Promise <sequence <BluetoothRemoteGATTService >>getPrimaryServices (optional BluetoothServiceUUID ); };
service
BluetoothRemoteGATTServer
attributes device
is the device running this server.
connected
is true while this instance
is connected to this.device
.
It can be false while the UA is physically connected,
for example when there are other connected BluetoothRemoteGATTServer
instances
for other global objects.
When no ECMAScript code can
observe an instance of BluetoothRemoteGATTServer
server anymore,
the UA SHOULD run server.
. Because disconnect()
BluetoothDevice
instances are stored in navigator.bluetooth.
,
this can’t happen at least until navigation releases the global object or
closing the tab or window destroys the browsing context. Disconnecting on garbage collection ensures that
the UA doesn’t keep consuming resources on the remote device unnecessarily. [[deviceInstanceMap]]
Instances of BluetoothRemoteGATTServer
are created with the internal slots described in the following table:
Internal Slot | Initial Value | Description (non-normative) |
---|---|---|
[[activeAlgorithms]]
| new
| Contains a Promise corresponding to each algorithm using this server’s connection. disconnect() empties this set so that
the algorithm can tell whether its realm was ever disconnected while it was running.
|
The
method, when invoked,
MUST perform the following steps: connect()
- Let promise be a new promise.
- If
this.device.
is[[representedDevice]]
null
, queue a task to reject promise with aNetworkError
, return promise, and abort these steps. -
If the UA is currently using the Bluetooth system,
it MAY queue a task to reject promise with a
NetworkError
, return promise, and abort these steps.Implementations may be able to avoid this
NetworkError
, but for now sites need to serialize their use of this API and/or give the user a way to retry failed operations. <https://github.com/WebBluetoothCG/web-bluetooth/issues/188> - Add promise to
this.
.[[activeAlgorithms]]
-
Return promise and run the following steps in parallel:
-
If
this.device.
has no ATT Bearer, do the following sub-steps:[[representedDevice]]
-
Attempt to create an ATT Bearer using the procedures described
in "Connection Establishment" under GAP Interoperability Requirements.
Abort this attempt if promise is removed from
this.
.[[activeAlgorithms]]
Note: These procedures can wait forever if a connectable advertisement isn’t received. The website should call
disconnect()
if it no longer wants to connect. - If this attempt was aborted because promise was removed from
this.
, reject promise with an[[activeAlgorithms]]
AbortError
and abort these steps. - If this attempt failed for another reason, reject promise with a
NetworkError
and abort these steps. - Use the Exchange MTU procedure to negotiate the largest supported MTU. Ignore any errors from this step.
-
The UA MAY attempt to bond with the remote device using
the BR/EDR Bonding Procedure or
the LE Bonding Procedure.
Note: We would normally prefer to give the website control over whether and when bonding happens, but the Core Bluetooth platform API doesn’t provide a way for UAs to implement such a knob. Having a bond is more secure than not having one, so this specification allows the UA to opportunistically create one on platforms where that’s possible. This may cause a user-visible pairing dialog to appear when a connection is created, instead of when a restricted characteristic is accessed.
-
Attempt to create an ATT Bearer using the procedures described
in "Connection Establishment" under GAP Interoperability Requirements.
Abort this attempt if promise is removed from
-
Queue a task to perform the following sub-steps:
- If promise is not in
this.
, reject promise with an[[activeAlgorithms]]
AbortError
, garbage-collect the connection ofthis.
, and abort these steps.[[representedDevice]]
- Remove promise from
this.
.[[activeAlgorithms]]
- If
this.device.
is[[representedDevice]]
null
, reject promise with aNetworkError
, garbage-collect the connection ofthis.
, and abort these steps.[[representedDevice]]
- Set
this.connected
totrue
. - Resolve promise with
this
.
- If promise is not in
-
If
The
method, when invoked,
MUST perform the following steps: disconnect()
- Clear
this.
to abort any active[[activeAlgorithms]]
connect()
calls. - If
this.
isconnected
false
, abort these steps. - Clean up the disconnected device
this.device
. - Let device be
this.device.
.[[representedDevice]]
- Garbage-collect the connection of device.
To garbage-collect the connection of a device, the UA must, do the following steps in parallel:
- If systems that aren’t using this API, either inside or outside of the UA, are using the device’s ATT Bearer, abort this algorithm.
-
For all
BluetoothDevice
sdeviceObj
in the whole UA:- If
deviceObj.
is not the same device as device, continue to the next deviceObj.[[representedDevice]]
- If
deviceObj.gatt.
isconnected
true
, abort this algorithm. - If
deviceObj.gatt.
contains the[[activeAlgorithms]]
Promise
of a call toconnect()
, abort this algorithm.
- If
- Destroy device’s ATT Bearer.
Algorithms need to fail if
their BluetoothRemoteGATTServer
was disconnected while they were running,
even if the UA stays connected the whole time
and the BluetoothRemoteGATTServer
is subsequently re-connected before they finish.
We wrap the returned Promise
to accomplish this.
To create a gattServer-connection-checking wrapper around a Promise
promise, the UA MUST:
- If
gattServer.connected
istrue
, add promise togattServer.
.[[activeAlgorithms]]
-
Return the result of transforming promise with fulfillment and rejection handlers that perform the following steps:
- fulfillment handler
-
- If promise is in
gattServer.
, remove it and return the first argument.[[activeAlgorithms]]
- Otherwise, throw a
NetworkError
. Because gattServer was disconnected during the execution of the main algorithm.
- If promise is in
- rejection handler
-
- If promise is in
gattServer.
, remove it and throw the first argument.[[activeAlgorithms]]
- Otherwise, throw a
NetworkError
. Because gattServer was disconnected during the execution of the main algorithm.
- If promise is in
The
method, when invoked,
MUST perform the following steps: getPrimaryService(service)
- If
this.device.
is not[[allowedServices]]
"all"
and service is not inthis.device.
, return a promise rejected with a[[allowedServices]]
SecurityError
and abort these steps. - Return GetGATTChildren(attribute=
this.device
,
single=true,
uuidCanonicalizer=BluetoothUUID.getService
,
uuid=service
,
allowedUuids=this.device.
,[[allowedServices]]
child type="GATT Primary Service")
The
method, when invoked,
MUST perform the following steps: getPrimaryServices(service)
- If
this.device.
is not[[allowedServices]]
"all"
, and service is present and not inthis.device.
, return a promise rejected with a[[allowedServices]]
SecurityError
and abort these steps. - Return GetGATTChildren(attribute=
this.device
,
single=false,
uuidCanonicalizer=BluetoothUUID.getService
,
uuid=service
,
allowedUuids=this.device.
,[[allowedServices]]
child type="GATT Primary Service")
5.3. BluetoothRemoteGATTService
BluetoothRemoteGATTService
represents a GATT Service,
a collection of characteristics and relationships to other services
that encapsulate the behavior of part of a device.
[Exposed =Window ,SecureContext ]interface BluetoothRemoteGATTService :EventTarget { [SameObject ]readonly attribute BluetoothDevice device ;readonly attribute UUID uuid ;readonly attribute boolean isPrimary ;Promise <BluetoothRemoteGATTCharacteristic >getCharacteristic (BluetoothCharacteristicUUID );
characteristic Promise <sequence <BluetoothRemoteGATTCharacteristic >>getCharacteristics (optional BluetoothCharacteristicUUID );
characteristic Promise <BluetoothRemoteGATTService >getIncludedService (BluetoothServiceUUID );
service Promise <sequence <BluetoothRemoteGATTService >>getIncludedServices (optional BluetoothServiceUUID ); };
service BluetoothRemoteGATTService includes CharacteristicEventHandlers ;BluetoothRemoteGATTService includes ServiceEventHandlers ;
BluetoothRemoteGATTService
attributes device
is the BluetoothDevice
representing
the remote peripheral that the GATT service belongs to.
uuid
is the UUID of the service,
e.g. '0000180d-0000-1000-8000-00805f9b34fb'
for the Heart Rate service.
isPrimary
indicates whether the type of this service is primary or secondary.
Instances of BluetoothRemoteGATTService
are created with the internal slots described in the following table:
Internal Slot | Initial Value | Description (non-normative) |
---|---|---|
[[representedService]]
| <always set in prose> | The Service this object represents,
or null if the Service has been removed or otherwise invalidated.
|
To create a BluetoothRemoteGATTService
representing a Service service,
the UA must return a new promise promise and run the following steps in parallel.
- Let result be a new instance of
BluetoothRemoteGATTService
with its[[representedService]]
slot initialized to service. - Get the
BluetoothDevice
representing the device in which service appears, and let device be the result. - If the previous step threw an error, reject promise with that error and abort these steps.
- Initialize
result.device
from device. - Initialize
result.uuid
from the UUID of service. - If service is a Primary Service,
initialize
result.isPrimary
to true. Otherwise initializeresult.isPrimary
to false. - Resolve promise with result.
The
method
retrieves a Characteristic inside this Service.
When invoked, it MUST return getCharacteristic(characteristic)
GetGATTChildren(attribute=this
,
single=true,
uuidCanonicalizer=BluetoothUUID.getCharacteristic
,
uuid=characteristic
,
allowedUuids=undefined
,
child type="GATT Characteristic")
The
method
retrieves a list of Characteristics inside this Service.
When invoked, it MUST return getCharacteristics(characteristic)
GetGATTChildren(attribute=this
,
single=false,
uuidCanonicalizer=BluetoothUUID.getCharacteristic
,
uuid=characteristic
,
allowedUuids=undefined
,
child type="GATT Characteristic")
The
method
retrieves an Included Service inside this Service.
When invoked, it MUST return getIncludedService(service)
GetGATTChildren(attribute=this
,
single=true,
uuidCanonicalizer=BluetoothUUID.getService
,
uuid=service
,
allowedUuids=undefined
,
child type="GATT Included Service")
The
method
retrieves a list of Included Services inside this Service.
When invoked, it MUST return getIncludedServices(service)
GetGATTChildren(attribute=this
,
single=false,
uuidCanonicalizer=BluetoothUUID.getService
,
uuid=service
,
allowedUuids=undefined
,
child type="GATT Included Service")
5.4. BluetoothRemoteGATTCharacteristic
BluetoothRemoteGATTCharacteristic
represents a GATT Characteristic, which is a basic data element that provides further information about a peripheral’s service.
[Exposed =Window ,SecureContext ]interface BluetoothRemoteGATTCharacteristic :EventTarget { [SameObject ]readonly attribute BluetoothRemoteGATTService service ;readonly attribute UUID uuid ;readonly attribute BluetoothCharacteristicProperties properties ;readonly attribute DataView ?value ;Promise <BluetoothRemoteGATTDescriptor >getDescriptor (BluetoothDescriptorUUID );
descriptor Promise <sequence <BluetoothRemoteGATTDescriptor >>getDescriptors (optional BluetoothDescriptorUUID );
descriptor Promise <DataView >readValue ();Promise <void >writeValue (BufferSource );
value Promise <void >writeValueWithResponse (BufferSource );
value Promise <void >writeValueWithoutResponse (BufferSource );
value Promise <BluetoothRemoteGATTCharacteristic >startNotifications ();Promise <BluetoothRemoteGATTCharacteristic >stopNotifications (); };BluetoothRemoteGATTCharacteristic includes CharacteristicEventHandlers ;
BluetoothRemoteGATTCharacteristic
attributes service
is the GATT service this characteristic belongs to.
uuid
is the UUID of the characteristic,
e.g. '00002a37-0000-1000-8000-00805f9b34fb'
for the Heart Rate Measurement characteristic.
properties
holds the properties of this characteristic.
value
is the currently cached characteristic value.
This value gets updated when the value of the characteristic is read or updated via a notification or indication.
Instances of BluetoothRemoteGATTCharacteristic
are created with the internal slots described in the following table:
Internal Slot | Initial Value | Description (non-normative) |
---|---|---|
[[representedCharacteristic]]
| <always set in prose> | The Characteristic this object represents,
or null if the Characteristic has been removed or otherwise invalidated.
|
To create a BluetoothRemoteGATTCharacteristic
representing a Characteristic characteristic,
the UA must return a new promise promise and run the following steps in parallel.
- Let result be a new instance of
BluetoothRemoteGATTCharacteristic
with its[[representedCharacteristic]]
slot initialized to characteristic. - Initialize
result.service
from theBluetoothRemoteGATTService
instance representing the Service in which characteristic appears. - Initialize
result.uuid
from the UUID of characteristic. - Create a
BluetoothCharacteristicProperties
instance from the Characteristic characteristic, and let propertiesPromise be the result. - Wait for propertiesPromise to settle.
- If propertiesPromise was rejected, resolve promise with propertiesPromise and abort these steps.
- Initialize
result.properties
from the value propertiesPromise was fulfilled with. - Initialize
result.value
tonull
. The UA MAY initializeresult.value
to a newDataView
wrapping a newArrayBuffer
containing the most recently read value from characteristic if this value is available. - Resolve promise with result.
The
method
retrieves a Descriptor inside this Characteristic.
When invoked, it MUST return getDescriptor(descriptor)
GetGATTChildren(attribute=this
,
single=true,
uuidCanonicalizer=BluetoothUUID.getDescriptor
,
uuid=descriptor
,
allowedUuids=undefined
,
child type="GATT Descriptor")
The
method
retrieves a list of Descriptors inside this Characteristic.
When invoked, it MUST return getDescriptors(descriptor)
GetGATTChildren(attribute=this
,
single=false,
uuidCanonicalizer=BluetoothUUID.getDescriptor
,
uuid=descriptor
,
allowedUuids=undefined
,
child type="GATT Descriptor")
The
method, when invoked,
MUST run the following steps: readValue()
- If
this.uuid
is blocklisted for reads, return a promise rejected with aSecurityError
and abort these steps. - If
this.service.device.gatt.
isconnected
false
, return a promise rejected with aNetworkError
and abort these steps. - Let characteristic be
this.
.[[representedCharacteristic]]
- If characteristic is
null
, return a promise rejected with anInvalidStateError
and abort these steps. -
Return a
this.service.device.gatt
-connection-checking wrapper around a new promise promise and run the following steps in parallel:- If the
Read
bit is not set in characteristic’s properties, reject promise with aNotSupportedError
and abort these steps. -
If the UA is currently using the Bluetooth system,
it MAY reject promise with a
NetworkError
and abort these steps.Implementations may be able to avoid this
NetworkError
, but for now sites need to serialize their use of this API and/or give the user a way to retry failed operations. <https://github.com/WebBluetoothCG/web-bluetooth/issues/188> - Use any combination of the sub-procedures in the Characteristic Value Read procedure to retrieve the value of characteristic. Handle errors as described in § 5.7 Error handling.
- If the previous step returned an error, reject promise with that error and abort these steps.
-
Queue a task to perform the following steps:
- If promise is not in
this.service.device.gatt.
, reject promise with a[[activeAlgorithms]]
NetworkError
and abort these steps. - Let buffer be an
ArrayBuffer
holding the retrieved value, and assignnew DataView(buffer)
tothis.value
. - Fire an event named
characteristicvaluechanged
with itsbubbles
attribute initialized totrue
atthis
. - Resolve promise with
this.value
.
- If promise is not in
- If the
To WriteCharacteristicValue(this: BluetoothRemoteGATTCharacteristic,
value: BufferSource,
response: string),
the UA MUST perform the following steps:
- If
this.uuid
is blocklisted for writes, return a promise rejected with aSecurityError
and abort these steps. - Let bytes be a copy of the bytes held by
value
. - If bytes is more than 512 bytes long
(the maximum length of an attribute value, per Long Attribute Values)
return a promise rejected with an
InvalidModificationError
and abort these steps. - If
this.service.device.gatt.
isconnected
false
, return a promise rejected with aNetworkError
and abort these steps. - Let characteristic be
this.
.[[representedCharacteristic]]
- If characteristic is
null
, return a promise rejected with anInvalidStateError
and abort these steps. -
Return a
this.service.device.gatt
-connection-checking wrapper around a new promise promise and run the following steps in parallel.- Assert: response is one of "required", "never", or "optional".
-
Reject promise with a
NotSupportedError
and abort these steps if any of the following is true:- response is "required" and
Write
bit is not set in characteristic’s properties - response is "never" and none of
Write Without Response
orAuthenticated Signed Writes
bits are set in characteristic’s properties - response is "optional" and none of the
Write
,Write Without Response
orAuthenticated Signed Writes
bits are set in characteristic’s properties
- response is "required" and
-
If the UA is currently using the Bluetooth system,
it MAY reject promise with a
NetworkError
and abort these steps.Implementations may be able to avoid this
NetworkError
, but for now sites need to serialize their use of this API and/or give the user a way to retry failed operations. <https://github.com/WebBluetoothCG/web-bluetooth/issues/188> -
Write bytes to characteristic by performing
the following steps:
- If response is "required"
- Use the Write Characteristic Value procedure.
- If response is "never"
- Use the Write Without Response procedure.
- Otherwise
- Use any combination of the sub-procedures in the Characteristic Value Write procedure.
- If the previous step returned an error, reject promise with that error and abort these steps.
-
Queue a task to perform the following steps:
- If promise is not in
this.service.device.gatt.
, reject promise with a[[activeAlgorithms]]
NetworkError
and abort these steps. - Set
this.value
to a newDataView
wrapping a newArrayBuffer
containing bytes. - Resolve promise with
undefined
.
- If promise is not in
The
method,
when invoked, MUST return writeValue(value)
WriteCharacteristicValue(this=this
,
value=value
,
response="optional")
The
method,
when invoked, MUST return writeValueWithResponse(value)
WriteCharacteristicValue(this=this
,
value=value
,
response="required")
The
method,
when invoked, MUST return writeValueWithoutResponse(value)
WriteCharacteristicValue(this=this
,
value=value
,
response="never")
The UA MUST maintain a map from each known GATT Characteristic to
a set of Bluetooth
objects known as
the characteristic’s active notification context set. The set for a given characteristic holds
the navigator.bluetooth
objects for
each Realm that has registered for notifications.
All notifications become inactive when a device is disconnected.
A site that wants to keep getting notifications after reconnecting
needs to call startNotifications()
again,
and there is an unavoidable risk that
some notifications will be missed
in the gap before startNotifications()
takes effect.
The
method, when invoked,
MUST return a new promise promise and run the following steps in parallel.
See § 5.6.4 Responding to Notifications and Indications for details of receiving notifications. startNotifications()
- If
this.uuid
is blocklisted for reads, reject promise with aSecurityError
and abort these steps. - If
this.service.device.gatt.
isconnected
false
, reject promise with aNetworkError
and abort these steps. - Let characteristic be
this.
.[[representedCharacteristic]]
- If characteristic is
null
, return a promise rejected with anInvalidStateError
and abort these steps. - If neither of the
Notify
orIndicate
bits are set in characteristic’s properties, reject promise with aNotSupportedError
and abort these steps. - If characteristic’s active notification context set contains
navigator.bluetooth
, resolve promise withthis
and abort these steps. -
If the UA is currently using the Bluetooth system,
it MAY reject promise with a
NetworkError
and abort these steps.Implementations may be able to avoid this
NetworkError
, but for now sites need to serialize their use of this API and/or give the user a way to retry failed operations. <https://github.com/WebBluetoothCG/web-bluetooth/issues/188> -
If the characteristic has a Client Characteristic Configuration descriptor, use any of the Characteristic Descriptors procedures
to ensure that one of the
Notification
orIndication
bits in characteristic’s Client Characteristic Configuration descriptor is set, matching the constraints in characteristic’s properties. The UA SHOULD avoid setting both bits, and MUST deduplicate value-change events if both bits are set. Handle errors as described in § 5.7 Error handling.Note: Some devices have characteristics whose properties include the Notify or Indicate bit but that don’t have a Client Characteristic Configuration descriptor. These non-standard-compliant characteristics tend to send notifications or indications unconditionally, so this specification allows applications to simply subscribe to their messages.
- If the previous step returned an error, reject promise with that error and abort these steps.
- Add
navigator.bluetooth
to characteristic’s active notification context set. - Resolve promise with
this
.
After notifications are enabled,
the resulting value-change events won’t be delivered
until after the current microtask checkpoint.
This allows a developer to set up handlers
in the .then
handler of the result promise.
The
method, when invoked,
MUST return a new promise promise and run the following steps in parallel: stopNotifications()
- Let characteristic be
this.
.[[representedCharacteristic]]
- If characteristic is
null
, return a promise rejected with anInvalidStateError
and abort these steps. - If characteristic’s active notification context set contains
navigator.bluetooth
, remove it. - If characteristic’s active notification context set became empty
and the characteristic has a Client Characteristic Configuration descriptor,
the UA SHOULD use any of the Characteristic Descriptors procedures
to clear the
Notification
andIndication
bits in characteristic’s Client Characteristic Configuration descriptor. - Queue a task to resolve promise with
this
.
Queuing a task to resolve the promise ensures that no value change events due to notifications arrive after the promise resolves.
5.4.1. BluetoothCharacteristicProperties
Each BluetoothRemoteGATTCharacteristic
exposes its characteristic properties through a BluetoothCharacteristicProperties
object.
These properties express what operations are valid on the characteristic.
[Exposed =Window ,SecureContext ]interface BluetoothCharacteristicProperties {readonly attribute boolean ;
broadcast readonly attribute boolean ;
read readonly attribute boolean ;
writeWithoutResponse readonly attribute boolean ;
write readonly attribute boolean ;
notify readonly attribute boolean ;
indicate readonly attribute boolean ;
authenticatedSignedWrites readonly attribute boolean ;
reliableWrite readonly attribute boolean ; };
writableAuxiliaries
To create a BluetoothCharacteristicProperties
instance
from the Characteristic characteristic,
the UA MUST return a new promise promise and run the following steps in parallel:
- Let propertiesObj be a new instance of
BluetoothCharacteristicProperties
. - Let properties be the characteristic properties of characteristic.
-
Initialize the attributes of propertiesObj from
the corresponding bits in properties:
Attribute Bit broadcast
Broadcast read
Read writeWithoutResponse
Write Without Response write
Write notify
Notify indicate
Indicate authenticatedSignedWrites
Authenticated Signed Writes -
If the Extended Properties bit of the characteristic properties is not set,
initialize
propertiesObj.reliableWrite
andpropertiesObj.writableAuxiliaries
tofalse
. Otherwise, run the following steps:-
Discover the Characteristic Extended Properties descriptor for characteristic and read its value into extendedProperties.
Handle errors as described in § 5.7 Error handling.
Characteristic Extended Properties isn’t clear whether the extended properties are immutable for a given Characteristic. If they are, the UA should be allowed to cache them.
- If the previous step returned an error, reject promise with that error and abort these steps.
- Initialize
propertiesObj.reliableWrite
from the Reliable Write bit of extendedProperties. - Initialize
propertiesObj.writableAuxiliaries
from the Writable Auxiliaries bit of extendedProperties.
-
Discover the Characteristic Extended Properties descriptor for characteristic and read its value into extendedProperties.
Handle errors as described in § 5.7 Error handling.
- Resolve promise with propertiesObj.
5.5. BluetoothRemoteGATTDescriptor
BluetoothRemoteGATTDescriptor
represents a GATT Descriptor, which provides further information about a Characteristic’s value.
[Exposed =Window ,SecureContext ]interface BluetoothRemoteGATTDescriptor { [SameObject ]readonly attribute BluetoothRemoteGATTCharacteristic characteristic ;readonly attribute UUID uuid ;readonly attribute DataView ?value ;Promise <DataView >readValue ();Promise <void >writeValue (BufferSource ); };
value
BluetoothRemoteGATTDescriptor
attributes characteristic
is the GATT characteristic this descriptor belongs to.
uuid
is the UUID of the characteristic descriptor,
e.g. '00002902-0000-1000-8000-00805f9b34fb'
for the Client Characteristic Configuration descriptor.
value
is the currently cached descriptor value.
This value gets updated when the value of the descriptor is read.
Instances of BluetoothRemoteGATTDescriptor
are created with the internal slots described in the following table:
Internal Slot | Initial Value | Description (non-normative) |
---|---|---|
[[representedDescriptor]]
| <always set in prose> | The Descriptor this object represents,
or null if the Descriptor has been removed or otherwise invalidated.
|
To create a BluetoothRemoteGATTDescriptor
representing a Descriptor descriptor,
the UA must return a new promise promise and run the following steps in parallel.
- Let result be a new instance of
BluetoothRemoteGATTDescriptor
with its[[representedDescriptor]]
slot initialized to descriptor. - Initialize
result.characteristic
from theBluetoothRemoteGATTCharacteristic
instance representing the Characteristic in which descriptor appears. - Initialize
result.uuid
from the UUID of descriptor. - Initialize
result.value
tonull
. The UA MAY initializeresult.value
to a newDataView
wrapping a newArrayBuffer
containing the most recently read value from descriptor if this value is available. - Resolve promise with result.
The
method, when invoked,
MUST run the following steps: readValue()
- If
this.uuid
is blocklisted for reads, return a promise rejected with aSecurityError
and abort these steps. - If
this.characteristic.service.device.gatt.
isconnected
false
, return a promise rejected with aNetworkError
and abort these steps. - Let descriptor be
this.
.[[representedDescriptor]]
- If descriptor is
null
, return a promise rejected with anInvalidStateError
and abort these steps. -
Return a
this.characteristic.service.device.gatt
-connection-checking wrapper around a new promise promise and run the following steps in parallel:-
If the UA is currently using the Bluetooth system,
it MAY reject promise with a
NetworkError
and abort these steps.Implementations may be able to avoid this
NetworkError
, but for now sites need to serialize their use of this API and/or give the user a way to retry failed operations. <https://github.com/WebBluetoothCG/web-bluetooth/issues/188> - Use either the Read Characteristic Descriptors or the Read Long Characteristic Descriptors sub-procedure to retrieve the value of descriptor. Handle errors as described in § 5.7 Error handling.
- If the previous step returned an error, reject promise with that error and abort these steps.
-
Queue a task to perform the following steps:
- If promise is not in
this.characteristic.service.device.gatt.
, reject promise with a[[activeAlgorithms]]
NetworkError
and abort these steps. - Let buffer be an
ArrayBuffer
holding the retrieved value, and assignnew DataView(buffer)
tothis.value
. - Resolve promise with
this.value
.
- If promise is not in
-
If the UA is currently using the Bluetooth system,
it MAY reject promise with a
The
method, when invoked,
MUST run the following steps: writeValue(value)
- If
this.uuid
is blocklisted for writes, return a promise rejected with aSecurityError
and abort these steps. - Let bytes be a copy of the bytes held by
value
. - If bytes is more than 512 bytes long
(the maximum length of an attribute value, per Long Attribute Values)
return a promise rejected with an
InvalidModificationError
and abort these steps. - If
this.characteristic.service.device.gatt.
isconnected
false
, return a promise rejected with aNetworkError
and abort these steps. - Let descriptor be
this.
.[[representedDescriptor]]
- If descriptor is
null
, return a promise rejected with anInvalidStateError
and abort these steps. -
Return a
this.characteristic.service.device.gatt
-connection-checking wrapper around a new promise promise and run the following steps in parallel.-
If the UA is currently using the Bluetooth system,
it MAY reject promise with a
NetworkError
and abort these steps.Implementations may be able to avoid this
NetworkError
, but for now sites need to serialize their use of this API and/or give the user a way to retry failed operations. <https://github.com/WebBluetoothCG/web-bluetooth/issues/188> - Use either the Write Characteristic Descriptors or the Write Long Characteristic Descriptors sub-procedure to write bytes to descriptor. Handle errors as described in § 5.7 Error handling.
- If the previous step returned an error, reject promise with that error and abort these steps.
-
Queue a task to perform the following steps:
- If promise is not in
this.characteristic.service.device.gatt.
, reject promise with a[[activeAlgorithms]]
NetworkError
and abort these steps. - Set
this.value
to a newDataView
wrapping a newArrayBuffer
containing bytes. - Resolve promise with
undefined
.
- If promise is not in
-
If the UA is currently using the Bluetooth system,
it MAY reject promise with a
5.6. Events
5.6.1. Bluetooth Tree
navigator.bluetooth
and
objects implementing the BluetoothDevice
, BluetoothRemoteGATTService
, BluetoothRemoteGATTCharacteristic
, or BluetoothRemoteGATTDescriptor
interface participate in a tree,
simply named the Bluetooth tree.
- The children of
navigator.bluetooth
are theBluetoothDevice
objects representing devices in theallowedDevices
list in"bluetooth"
's extra permission data fornavigator.bluetooth
's relevant settings object, in an unspecified order. - The children of a
BluetoothDevice
are theBluetoothRemoteGATTService
objects representing Primary and Secondary Services on its GATT Server whose UUIDs are on the origin and device’sallowedServices
list. The order of the primary services MUST be consistent with the order returned by the Discover Primary Service by Service UUID procedure, but secondary services and primary services with different UUIDs may be in any order. - The children of a
BluetoothRemoteGATTService
are theBluetoothRemoteGATTCharacteristic
objects representing its Characteristics. The order of the characteristics MUST be consistent with the order returned by the Discover Characteristics by UUID procedure, but characteristics with different UUIDs may be in any order. - The children of a
BluetoothRemoteGATTCharacteristic
are theBluetoothRemoteGATTDescriptor
objects representing its Descriptors in the order returned by the Discover All Characteristic Descriptors procedure.
5.6.2. Event types
advertisementreceived
- Fired on a
BluetoothDevice
when an advertising event is received from that device. availabilitychanged
- Fired on
navigator.bluetooth
when the Bluetooth system as a whole becomes available or unavailable to the UA. characteristicvaluechanged
- Fired on a
BluetoothRemoteGATTCharacteristic
when its value changes, either as a result of a read request, or a value change notification/indication. gattserverdisconnected
- Fired on a
BluetoothDevice
when an active GATT connection is lost. serviceadded
- Fired on a new
BluetoothRemoteGATTService
when it has been discovered on a remote device, just after it is added to the Bluetooth tree. servicechanged
- Fired on a
BluetoothRemoteGATTService
when its state changes. This involves any characteristics and/or descriptors that get added or removed from the service, as well as Service Changed indications from the remote device. serviceremoved
- Fired on a
BluetoothRemoteGATTService
when it has been removed from its device, just before it is removed from the Bluetooth tree.
5.6.3. Responding to Disconnection
When a Bluetooth device device’s ATT Bearer is lost
(e.g. because the remote device moved out of range
or the user used a platform feature to disconnect it),
for each BluetoothDevice
deviceObj the UA MUST queue a task on deviceObj’s relevant settings object’s responsible event loop to perform the following steps:
- If
deviceObj.
is not the same device as device, abort these steps.[[representedDevice]]
- If
!deviceObj.gatt.
, abort these steps.connected
- Clean up the disconnected device deviceObj.
To clean up the disconnected device deviceObj, the UA must:
- Set
deviceObj.gatt.
toconnected
false
. - Clear
deviceObj.gatt.
.[[activeAlgorithms]]
- Let context be
deviceObj.
.[[context]]
- Remove all entries from
context.
whose keys are inside[[attributeInstanceMap]]
deviceObj.
.[[representedDevice]]
- For each
BluetoothRemoteGATTService
service in deviceObj’s realm, setservice.
to[[representedService]]
null
. -
For each
BluetoothRemoteGATTCharacteristic
characteristic in deviceObj’s realm, do the following sub-steps:- Let notificationContexts be
characteristic.
’s active notification context set.[[representedCharacteristic]]
- Remove context from notificationContexts.
- If notificationContexts became empty
and there is still an ATT Bearer to
deviceObj.
and characteristic has a Client Characteristic Configuration descriptor, the UA SHOULD use any of the Characteristic Descriptors procedures to clear the[[representedDevice]]
Notification
andIndication
bits in characteristic’s Client Characteristic Configuration descriptor. - Set
characteristic.
to[[representedCharacteristic]]
null
.
- Let notificationContexts be
- For each
BluetoothRemoteGATTDescriptor
descriptor in deviceObj’s realm, setdescriptor.
to[[representedDescriptor]]
null
. -
Fire an event named
gattserverdisconnected
with itsbubbles
attribute initialized totrue
atdeviceObj
.This event is not fired at the
BluetoothRemoteGATTServer
.
5.6.4. Responding to Notifications and Indications
When the UA receives a Bluetooth Characteristic Value Notification or Indication, it must perform the following steps:
-
For each bluetoothGlobal in
the Characteristic’s active notification context set, queue a task on the event loop of the script settings object of bluetoothGlobal to do the following sub-steps:
- Let characteristicObject be the
BluetoothRemoteGATTCharacteristic
in the Bluetooth tree rooted at bluetoothGlobal that represents the Characteristic. - If
characteristicObject.service.device.gatt.
isconnected
false
, abort these sub-steps. - Set
characteristicObject.value
to a newDataView
wrapping a newArrayBuffer
holding the new value of the Characteristic. - Fire an event named
characteristicvaluechanged
with itsbubbles
attribute initialized totrue
at characteristicObject.
- Let characteristicObject be the
5.6.5. Responding to Service Changes
The Bluetooth Attribute Caching system allows clients to track changes to Services, Characteristics, and Descriptors. Before discovering any of these attributes for the purpose of exposing them to a web page the UA MUST subscribe to Indications from the Service Changed characteristic, if it exists. When the UA receives an Indication on the Service Changed characteristic, it MUST perform the following steps.
- Let removedAttributes be the list of attributes in the range indicated by the Service Changed characteristic that the UA had discovered before the Indication.
- Use the Primary Service Discovery, Relationship Discovery, Characteristic Discovery, and Characteristic Descriptor Discovery procedures to re-discover attributes in the range indicated by the Service Changed characteristic. The UA MAY skip discovering all or part of the indicated range if it can prove that the results of that discovery could not affect the events fired below.
- Let addedAttributes be the list of attributes discovered in the previous step.
-
If an attribute with the same definition
(see the Service Interoperability Requirements),
ignoring Characteristic and Descriptor values,
appears in both removedAttributes and addedAttributes,
remove it from both.
Given the following device states:
- State 1
-
-
Service A
- Characteristic C: value
[1, 2, 3]
- Characteristic C: value
- Service B
-
Service A
- State 2
-
-
Service A
- Characteristic C: value
[3, 2, 1]
- Characteristic C: value
- Service B
-
Service A
- State 3
-
-
Service A
- Characteristic D: value
[3, 2, 1]
- Characteristic D: value
- Service B
-
Service A
- State 4
-
-
Service A
- Characteristic C: value
[1, 2, 3]
- Characteristic C: value
-
Service B
- Include Service A
-
Service A
A transition from state 1 to 2 leaves service A with "the same definition, ignoring Characteristic and Descriptor values", which means it’s removed from both removedAttributes and addedAttributes, and it wouldn’t appear in any
servicechanged
events.A transition from state 1 to 3 leaves service A with a different definition, because a service definition includes its characteristic definitions, so it’s left in both removedAttributes and addedAttributes. Then in step 8, the service is moved to changedServices, which makes it cause a
servicechanged
event instead of both aserviceadded
andserviceremoved
. Step 9 also adds service A to changedServices because characteristic C was removed and characteristic D was added.A transition from state 1 to 4 is similar to the 1->3 transition. Service B is moved to changedServices in step 8, but no characteristics or descriptors have changed, so it’s not redundantly added in step 9.
- Let invalidatedAttributes be the attributes in removedAttributes but not addedAttributes.
-
For each environment settings object settings in the UA, queue a task on its responsible event loop to
do the following sub-steps:
- For each
BluetoothRemoteGATTService
service whose relevant settings object is settings, ifservice.
is in invalidatedAttributes, set[[representedService]]
service.
to[[representedService]]
null
. - For each
BluetoothRemoteGATTCharacteristic
characteristic whose relevant settings object is settings, ifcharacteristic.
is in invalidatedAttributes, set[[representedCharacteristic]]
characteristic.
to[[representedCharacteristic]]
null
. - For each
BluetoothRemoteGATTDescriptor
descriptor whose relevant settings object is settings, ifdescriptor.
is in invalidatedAttributes, set[[representedDescriptor]]
descriptor.
to[[representedDescriptor]]
null
. - Let global be settings’ global object.
- Remove every entry
from
global.navigator.bluetooth.
that represents an attribute that is in invalidatedAttributes.[[attributeInstanceMap]]
- For each
- Let changedServices be a set of Services, initially empty.
- If the same Service appears in both removedAttributes and addedAttributes, remove it from both, and add it to changedServices.
- For each Characteristic and Descriptor in removedAttributes or addedAttributes, remove it from its original list, and add its parent Service to changedServices. After this point, removedAttributes and addedAttributes contain only Services.
- If a Service in addedAttributes would not have been returned from any previous call to
getPrimaryService
,getPrimaryServices
,getIncludedService
, orgetIncludedServices
if it had existed at the time of the call, the UA MAY remove the Service from addedAttributes. - Let changedDevices be the set of Bluetooth devices that contain any Service in removedAttributes, addedAttributes, and changedServices.
-
For each
BluetoothDevice
deviceObj that is connected to a device in changedDevices, queue a task on its relevant global object’s responsible event loop to do the following steps:-
For each Service service in removedAttributes:
- If
deviceObj.
is[[allowedServices]]
"all"
or contains the Service’s UUID, fire an event namedserviceremoved
with itsbubbles
attribute initialized totrue
at theBluetoothRemoteGATTService
representing the Service. - Remove this
BluetoothRemoteGATTService
from the Bluetooth tree.
- If
- For each Service in addedAttributes,
if
deviceObj.
is[[allowedServices]]
"all"
or contains the Service’s UUID, add theBluetoothRemoteGATTService
representing this Service to the Bluetooth tree and then fire an event namedserviceadded
with itsbubbles
attribute initialized totrue
at theBluetoothRemoteGATTService
. - For each Service in changedServices,
if
deviceObj.
is[[allowedServices]]
"all"
or contains the Service’s UUID, fire an event namedservicechanged
with itsbubbles
attribute initialized totrue
at theBluetoothRemoteGATTService
representing the Service.
-
For each Service service in removedAttributes:
5.6.6. IDL event handlers
[SecureContext ]interface mixin {
CharacteristicEventHandlers attribute EventHandler oncharacteristicvaluechanged ; };
oncharacteristicvaluechanged
is an Event handler IDL attribute for the characteristicvaluechanged
event type.
[SecureContext ]interface mixin {
BluetoothDeviceEventHandlers attribute EventHandler onadvertisementreceived ;attribute EventHandler ongattserverdisconnected ; };
onadvertisementreceived
is an Event handler IDL attribute for the advertisementreceived
event type.
ongattserverdisconnected
is an Event handler IDL attribute for the gattserverdisconnected
event type.
[SecureContext ]interface mixin {
ServiceEventHandlers attribute EventHandler onserviceadded ;attribute EventHandler onservicechanged ;attribute EventHandler onserviceremoved ; };
onserviceadded
is an Event handler IDL attribute for the serviceadded
event type.
onservicechanged
is an Event handler IDL attribute for the servicechanged
event type.
onserviceremoved
is an Event handler IDL attribute for the serviceremoved
event type.
5.7. Error handling
This section primarily defines the mapping from system errors to Javascript error names and allows UAs to retry certain operations. The retry logic and possible error distinctions are highly constrained by the operating system, so places these requirements don’t reflect reality are likely spec bugs instead of browser bugs.
When the UA is using a GATT procedure to execute a step in an algorithm or to handle a query to the Bluetooth cache (both referred to as a "step", here),
and the GATT procedure returns an Error Response
,
the UA MUST perform the following steps:
- If the procedure times out or
the ATT Bearer (described in Profile Fundamentals) is
absent or terminated for any reason,
return a
NetworkError
from the step and abort these steps. -
Take the following actions depending on the
Error Code
:Invalid PDU
Invalid Offset
Attribute Not Found
Unsupported Group Type
- These error codes indicate that something unexpected happened at the protocol layer,
likely either due to a UA or device bug.
Return a
NotSupportedError
from the step. Invalid Handle
- Return an
InvalidStateError
from the step. Invalid Attribute Value Length
- Return an
InvalidModificationError
from the step. Attribute Not Long
-
If this error code is received without having used a "Long" sub-procedure, this may indicate a device bug. Return a
NotSupportedError
from the step.Otherwise, retry the step without using a "Long" sub-procedure. If this is impossible due to the length of the value being written, return an
InvalidModificationError
from the step. Insufficient Authentication
Insufficient Encryption
Insufficient Encryption Key Size
- The UA SHOULD attempt to increase the security level of the connection.
If this attempt fails or the UA doesn’t support any higher security,
Return a
SecurityError
from the step. Otherwise, retry the step at the new higher security level. Insufficient Authorization
- Return a
SecurityError
from the step. Application Error
- If the GATT procedure was a Write,
return an
InvalidModificationError
from the step. Otherwise, return aNotSupportedError
from the step. Read Not Permitted
Write Not Permitted
Request Not Supported
Prepare Queue Full
Insufficient Resources
Unlikely Error
- Anything else
- Return a
NotSupportedError
from the step.
6. UUIDs
typedef DOMString ;
UUID
A UUID string represents a 128-bit [RFC4122] UUID.
A valid UUID is a string that matches
the [ECMAScript] regexp /^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/
.
That is, a valid UUID is lower-case and
does not use the 16- or 32-bit abbreviations defined by the Bluetooth standard.
All UUIDs returned from functions and attributes in this specification
MUST be valid UUIDs.
If a function in this specification takes a parameter whose type is UUID or a dictionary including a UUID attribute,
and the argument passed in any UUID slot is not a valid UUID,
the function MUST return a promise rejected with a TypeError
and abort its other steps.
This standard provides the BluetoothUUID.canonicalUUID(alias)
function
to map a 16- or 32-bit Bluetooth UUID alias to its 128-bit form.
Bluetooth devices are required to convert 16- and 32-bit UUIDs to 128-bit UUIDs before comparing them (as described in Attribute Type), but not all devices do so. To interoperate with these devices, if the UA has received a UUID from the device in one form (16-, 32-, or 128-bit), it should send other aliases of that UUID back to the device in the same form.
6.1. Standardized UUIDs
The Bluetooth SIG maintains a registry at [BLUETOOTH-ASSIGNED] of UUIDs that identify services, characteristics, descriptors, and other entities. This section provides a way for script to look up those UUIDs by name so they don’t need to be replicated in each application.
[Exposed =Window ]interface {
BluetoothUUID static UUID getService ((DOMString or unsigned long ));
name static UUID getCharacteristic ((DOMString or unsigned long ));
name static UUID getDescriptor ((DOMString or unsigned long ));
name static UUID canonicalUUID ([EnforceRange ]unsigned long ); };
alias typedef (DOMString or unsigned long )BluetoothServiceUUID ;typedef (DOMString or unsigned long )BluetoothCharacteristicUUID ;typedef (DOMString or unsigned long )BluetoothDescriptorUUID ;
The static BluetoothUUID.
method, when invoked,
MUST return the 128-bit UUID represented by the 16- or 32-bit UUID alias alias. canonicalUUID(alias)
This algorithm consists of
replacing the top 32 bits of "00000000-0000-1000-8000-00805f9b34fb
"
with the bits of the alias.
For example, canonicalUUID(0xDEADBEEF)
returns "deadbeef-0000-1000-8000-00805f9b34fb"
.
BluetoothServiceUUID
represents
16- and 32-bit UUID aliases, valid UUIDs,
and names defined in [BLUETOOTH-ASSIGNED-SERVICES],
or, equivalently, the values for which BluetoothUUID.getService()
does not throw an exception.
BluetoothCharacteristicUUID
represents
16- and 32-bit UUID aliases, valid UUIDs,
and names defined in [BLUETOOTH-ASSIGNED-CHARACTERISTICS],
or, equivalently, the values for which BluetoothUUID.getCharacteristic()
does not throw an exception.
BluetoothDescriptorUUID
represents
16- and 32-bit UUID aliases, valid UUIDs,
and names defined in [BLUETOOTH-ASSIGNED-DESCRIPTORS],
or, equivalently, the values for which BluetoothUUID.getDescriptor()
does not throw an exception.
To ResolveUUIDName(name, assigned numbers table, prefix), the UA MUST perform the following steps:
- If name is an
unsigned long
, returnBluetoothUUID.canonicalUUID
(name) and abort these steps. - If name is a valid UUID, return name and abort these steps.
- If the string
prefix + "." + name
appears in assigned numbers table, let alias be its assigned number, and returnBluetoothUUID.canonicalUUID
(alias). - Otherwise, throw a
TypeError
.
The static BluetoothUUID.
method, when invoked,
MUST return ResolveUUIDName(getService(name)
name
, [BLUETOOTH-ASSIGNED-SERVICES], "org.bluetooth.service").
The static BluetoothUUID.
method, when invoked,
MUST return ResolveUUIDName(getCharacteristic(name)
name
, [BLUETOOTH-ASSIGNED-CHARACTERISTICS], "org.bluetooth.characteristic").
The static BluetoothUUID.
method, when invoked,
MUST return ResolveUUIDName(getDescriptor(name)
name
, [BLUETOOTH-ASSIGNED-DESCRIPTORS], "org.bluetooth.descriptor").
returns BluetoothUUID.getService
(" cycling_power")"00001818-0000-1000-8000-00805f9b34fb"
.
returns BluetoothUUID.getService
("00001801-0000-1000-8000-00805f9b34fb")"00001801-0000-1000-8000-00805f9b34fb"
.
throws a BluetoothUUID.getService
("unknown-service")TypeError
.
returns BluetoothUUID.getCharacteristic
("ieee_11073-20601_regulatory_certification_data_list
")"00002a2a-0000-1000-8000-00805f9b34fb"
.
returns BluetoothUUID.getDescriptor
("gatt.characteristic_presentation_format
")"00002904-0000-1000-8000-00805f9b34fb"
.
7. The GATT Blocklist
This specification relies on a blocklist file in the https://github.com/WebBluetoothCG/registries repository to restrict the set of GATT attributes a website can access.
The result of parsing the blocklist at a URL url is a map from valid UUIDs to tokens, or an error, produced by the following algorithm:
- Fetch url, and let contents be its body, decoded as UTF-8.
- Let lines be contents split on
'\n'
. - Let result be an empty map.
-
For each line in lines, do the following sub-steps:
- If line is empty or its first character is
'#'
, continue to the next line. - If line consists of just a valid UUID,
let uuid be that UUID and
let token be "
exclude
". - If line consists of a valid UUID, a space (U+0020),
and one of the tokens "
exclude-reads
" or "exclude-writes
", let uuid be that UUID and let token be that token. - Otherwise, return an error and abort these steps.
- If uuid is already in result, return an error and abort these steps.
- Add a mapping in result from uuid to token.
- If line is empty or its first character is
- Return result.
The GATT blocklist is the result of parsing the blocklist at https://github.com/WebBluetoothCG/registries/blob/master/gatt_blocklist.txt. The UA should re-fetch the blocklist periodically, but it’s unspecified how often.
A UUID is blocklisted if either
the GATT blocklist’s value is an error,
or the UUID maps to "exclude
" in the GATT blocklist.
A UUID is blocklisted for reads if either
the GATT blocklist’s value is an error,
or the UUID maps to either "exclude
" or "exclude-reads
"
in the GATT blocklist.
A UUID is blocklisted for writes if either
the GATT blocklist’s value is an error,
or the UUID maps to either "exclude
" or "exclude-writes
"
in the GATT blocklist.
8. Extensions to the Navigator Interface
[SecureContext ]partial interface Navigator { [SameObject ]readonly attribute Bluetooth ; };
bluetooth
9. Terminology and Conventions
This specification uses a few conventions and several terms from other specifications. This section lists those and links to their primary definitions.
When an algorithm in this specification uses a name defined in this or another specification,
the name MUST resolve to its initial value,
ignoring any changes that have been made to the name in the current execution environment.
For example, when the requestDevice()
algorithm says to call
,
this MUST apply the Array.prototype.map
.call(filter.services, BluetoothUUID.getService
)Array.prototype.map
algorithm defined in [ECMAScript] with filter.services
as its this
parameter and
the algorithm defined in § 6.1 Standardized UUIDs for BluetoothUUID.getService
as its callbackfn
parameter,
regardless of any modifications that have been made to window
, Array
, Array.prototype
, Array.prototype.map
, Function
, Function.prototype
, BluetoothUUID
, BluetoothUUID.getService
, or other objects.
This specification uses a read-only type
that is similar to WebIDL’s FrozenArray
.
- A read only ArrayBuffer has
ArrayBuffer
's values and interface, except that attempting to write to its contents or transfer it has the same effect as trying to write to aFrozenArray
's contents. This applies toTypedArray
s andDataView
s wrapped around theArrayBuffer
too.
- [BLUETOOTH42]
-
-
Architecture & Terminology Overview
-
General Description
- Overview of Bluetooth Low Energy Operation (defines advertising events)
-
Communication Topology and Operation
-
Operational Procedures and Modes
-
BR/EDR Procedures
-
Inquiry (Discovering) Procedure
- Extended Inquiry Response
-
Inquiry (Discovering) Procedure
-
BR/EDR Procedures
-
Operational Procedures and Modes
-
General Description
-
Core System Package [BR/EDR Controller volume]
-
Host Controller Interface Functional Specification
-
HCI Commands and Events
-
Informational Parameters
- Read BD_ADDR Command
-
Status Parameters
- Read RSSI Command
-
Informational Parameters
-
HCI Commands and Events
-
Host Controller Interface Functional Specification
-
Core System Package [Host volume]
-
Service Discovery Protocol (SDP) Specification
-
Overview
-
Searching for Services
- UUID (defines UUID aliases and the algorithm to compute the 128-bit UUID represented by a UUID alias)
-
Searching for Services
-
Overview
-
Generic Access Profile
-
Profile Overview
-
Profile Roles
-
Roles when Operating over an LE Physical Transport
- Broadcaster Role
- Observer Role
- Peripheral Role
- Central Role
-
Roles when Operating over an LE Physical Transport
-
Profile Roles
-
User Interface Aspects
-
Representation of Bluetooth Parameters
- Bluetooth Device Name (the user-friendly name)
-
Representation of Bluetooth Parameters
-
Idle Mode Procedures — BR/EDR Physical Transport
- Device Discovery Procedure
- BR/EDR Bonding Procedure
-
Operational Modes and Procedures — LE Physical Transport
-
Broadcast Mode and Observation Procedure
- Observation Procedure
-
Discovery Modes and Procedures
- General Discovery Procedure
- Name Discovery Procedure
- Connection Modes and Procedures
-
Bonding Modes and Procedures
- LE Bonding Procedure
-
Broadcast Mode and Observation Procedure
-
Security Aspects — LE Physical Transport
- Privacy Feature
-
Random Device Address
- Static Address
-
Private address
- Resolvable Private Address Resolution Procedure
- Advertising Data and Scan Response Data Format (defines AD structure)
-
Bluetooth Device Requirements
-
Bluetooth Device Address (defines BD_ADDR)
-
Bluetooth Device Address Types
- Public Bluetooth Address
-
Bluetooth Device Address Types
-
Bluetooth Device Address (defines BD_ADDR)
- Definitions (defines bond)
-
Profile Overview
-
Attribute Protocol (ATT)
-
Protocol Requirements
-
Basic Concepts
- Attribute Type
- Attribute Handle
- Long Attribute Values
-
Attribute Protocol Pdus
-
Error Handling
- Error Response
-
Error Handling
-
Basic Concepts
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Protocol Requirements
-
Generic Attribute Profile (GATT)
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Profile Overview
- Configurations and Roles (defines GATT Client and GATT Server)
- Profile Fundamentals, defines the ATT Bearer
-
Attribute Protocol
- Attribute Caching
-
GATT Profile Hierarchy
- Service
- Included Services
- Characteristic
-
Service Interoperability Requirements
- Service Definition
-
Characteristic Definition
-
Characteristic Declaration
- Characteristic Properties
-
Characteristic Descriptor Declarations
- Characteristic Extended Properties
- Client Characteristic Configuration
-
Characteristic Declaration
-
GATT Feature Requirements — defines the GATT procedures.
-
Server Configuration
- Exchange MTU
-
Primary Service Discovery
- Discover All Primary Services
- Discover Primary Service by Service UUID
-
Relationship Discovery
- Find Included Services
-
Characteristic Discovery
- Discover All Characteristics of a Service
- Discover Characteristics by UUID
-
Characteristic Descriptor Discovery
- Discover All Characteristic Descriptors
- Characteristic Value Read
-
Characteristic Value Write
- Write Without Response
- Write Characteristic Value
- Characteristic Value Notification
- Characteristic Value Indications
-
Characteristic Descriptors
- Read Characteristic Descriptors
- Read Long Characteristic Descriptors
- Write Characteristic Descriptors
- Write Long Characteristic Descriptors
- Procedure Timeouts
-
Server Configuration
-
GAP Interoperability Requirements
-
BR/EDR GAP Interoperability Requirements
- Connection Establishment
-
LE GAP Interoperability Requirements
- Connection Establishment
-
BR/EDR GAP Interoperability Requirements
-
Defined Generic Attribute Profile Service
- Service Changed
-
Profile Overview
-
Security Manager Specification
-
Security Manager
-
Security in Bluetooth Low Energy
- Definition of Keys and Values, defines the Identity Resolving Key (IRK)
-
Security in Bluetooth Low Energy
-
Security Manager
-
Service Discovery Protocol (SDP) Specification
-
Core System Package [Low Energy Controller volume]
-
Link Layer Specification
-
General Description
-
Device Address
- Public Device Address
-
Random Device Address
- Static Device Address
-
Device Address
-
Air Interface Protocol
-
Non-Connected States
-
Scanning State
- Passive Scanning
-
Scanning State
-
Non-Connected States
-
General Description
-
Link Layer Specification
-
Architecture & Terminology Overview
- [BLUETOOTH-SUPPLEMENT6]
-
-
Data Types Specification
-
Data Types Definitions and Formats
- Service UUID Data Type
- Local Name Data Type
- Flags Data Type (defines the Discoverable Mode flags)
- Manufacturer Specific Data
- TX Power Level
- Service Data
- Appearance
-
Data Types Definitions and Formats
-
Data Types Specification