Publish/Subscribe API for PubNub JavaScript SDK
The foundation of the PubNub service is the ability to send a message and have it delivered anywhere in less than 100ms. Send a message to just one other person, or broadcast to thousands of subscribers at once.
For higher-level conceptual details on publishing and subscribing, refer to Connection Management and to Publish Messages.
Supported and recommended asynchronous patterns
PubNub supports Callbacks, Promises, and Async/Await for asynchronous JS operations. The recommended pattern is Async/Await and all sample requests in this document are based on it. This pattern returns a status only on detecting an error. To receive the status errors, you must use the try...catch
syntax in your code.
Publish
The publish()
function is used to send a message to all subscribers of a channel. To publish a message you must first specify a valid publishKey
at initialization. A successfully published message is replicated across the PubNub Real-Time Network and sent simultaneously to all subscribed clients on a channel.
Messages in transit can be secured from potential eavesdroppers with SSL/TLS by setting ssl to true during initialization.
Publish Anytime
It's not required to be subscribed to a channel in order to publish to that channel.
Message Data
The message argument can contain any JSON serializable data, including: Objects, Arrays, Ints and Strings. data
should not contain special JavaScript classes or functions as these will not serialize. String content can include any single-byte or multi-byte UTF-8 character.
Don't use JSON.stringify
It is important to note that you should not use JSON.stringify()
when sending signals/messages via PubNub. Why? Because the serialization is done for you automatically. Instead just pass the full object as the message payload. PubNub takes care of everything for you.
Message Size
The maximum number of characters per message is 32 KiB by default. The maximum message size is based on the final escaped character count, including the channel name. An ideal message size is under 1800 bytes which allows a message to be compressed and sent using single IP datagram (1.5 KiB) providing optimal network performance.
If the message you publish exceeds the configured size, you will receive the following message:
Message Too Large Error
["PUBLISHED",[0,"Message Too Large","13524237335750949"]]
For further details, check the support article.
Message Publish Rate
Messages can be published as fast as bandwidth conditions will allow. There is a soft limit based on max throughput since messages will be discarded if the subscriber can't keep pace with the publisher.
For example, if 200 messages are published simultaneously before a subscriber has had a chance to receive any messages, the subscriber may not receive the first 100 messages because the message queue has a limit of only 100 messages stored in memory.
Publishing to Multiple Channels
It is not possible to publish a message to multiple channels simultaneously. The message must be published to one channel at a time.
Publishing Messages Reliably
There are some best practices to ensure messages are delivered when publishing to a channel:
- Publish to any given channel in a serial manner (not concurrently).
- Check that the return code is success (for example,
[1,"Sent","136074940..."]
) - Publish the next message only after receiving a success return code.
- If a failure code is returned (
[0,"blah","<timetoken>"]
), retry the publish. - Avoid exceeding the in-memory queue's capacity of 100 messages. An overflow situation (aka missed messages) can occur if slow subscribers fail to keep up with the publish pace in a given period of time.
- Throttle publish bursts in accordance with your app's latency needs for example Publish no faster than 5 msgs per second to any one channel.
Method(s)
To Publish a message
, you can use the following method(s) in the JavaScript SDK:
pubnub.publish({
message: any,
channel: string,
meta: any,
storeInHistory: boolean,
sendByPost: boolean,
ttl: number
}): Promise<PublishResponse>;
Parameter | Type | Required | Default | Description |
---|---|---|---|---|
Operation Arguments | Hash | Yes | A hash of arguments. | |
message | any | Yes | The message may be any valid JSON type including objects, arrays, strings, and numbers. | |
channel | string | Yes | Specifies channel name to publish messages to. | |
storeInHistory | boolean | Optional | true | If true the messages are stored in history. If storeInHistory is not specified, then the history configuration on the key is used. |
sendByPost | boolean | Optional | false | When true , the SDK uses HTTP POST to publish the messages. The message is sent in the BODY of the request, instead of the query string when HTTP GET is used. Also the messages are compressed thus reducing the size of the messages. Using HTTP POST to publish messages adheres to RESTful API best practices. |
meta | any | Optional | Publish extra meta with the request. | |
ttl | number | Optional | Set a per message time to live in Message Persistence.
|
Basic Usage
Publish a message to a channel
try {
const result = await pubnub.publish({
message: {
such: "object",
},
channel: "my_channel",
sendByPost: false, // true to send via post
storeInHistory: false, //override default Message Persistence options
meta: {
cool: "meta",
}, // publish extra meta with the request
});
} catch (status) {
console.log(status);
}
Subscribe to the channel
Before running the above publish example, either using the Debug Console or in a separate script running in a separate terminal window, subscribe to the same channel that is being published to.
Response
type PublishResponse = {
timetoken: number
}
Other Examples
Publish a JSON serialized message
const newMessage = {
text: "Hi There!",
};
try {
const result = await pubnub.publish({
message: newMessage,
channel: "my_channel",
});
console.log("message published w/ server response: ", result);
} catch (status) {
console.log("publishing failed w/ status: ", status);
}
Store the published message for 10 hours
try {
const result = await pubnub.publish({
message: "hello!",
channel: "my_channel",
storeInHistory: true,
ttl: 10,
});
console.log("message published w/ server response: ", response);
} catch (status) {
console.log("publishing failed w/ status: ", status);
}
Publish successful
const result = await pubnub.publish({
message: "hello world!",
channel: "ch1",
});
console.log(response); // {timetoken: "14920301569575101"}
Publish unsuccessful by network down
try {
const result = await pubnub.publish({
message: "hello world!",
channel: "ch1",
});
} catch (status) {
console.log(status); // {error: true, operation: "PNPublishOperation", errorData: Error, category: "PNNetworkIssuesCategory"}
}
Publish unsuccessful by initialization without publishKey
try {
const result = await pubnub.publish({
message: "hello world!",
channel: "ch1",
});
} catch (status) {
console.log(status); // {error: true, operation: "PNPublishOperation", statusCode: 400, errorData: Error, category: "PNBadRequestCategory"}
}
Publish unsuccessful by missing channel
try {
const result = await pubnub.publish({
message: "hello world!",
});
} catch (status) {
console.log(status); // {message: "Missing Channel", type: "validationError", error: true}
}
Publish unsuccessful by missing message
try {
const result = await pubnub.publish({
channel: "ch1",
});
} catch (status) {
console.log(status); // {message: "Missing Message", type: "validationError", error: true}
}
Fire
The fire endpoint allows the client to send a message to Functions Event Handlers and Illuminate. These messages will go directly to any Event Handlers registered on the channel that you fire to and will trigger their execution. The content of the fired request will be available for processing within the Event Handler. The message sent via fire()
isn't replicated, and so won't be received by any subscribers to the channel. The message is also not stored in history.
Method(s)
To Fire a message
, you can use the following method(s) in the JavaScript SDK:
fire({
Object message,
String channel,
Boolean sendByPost,
Object meta
})
Parameter | Type | Required | Default | Description |
---|---|---|---|---|
Operation Arguments | Hash | Yes | A hash of arguments. | |
message | Object | Yes | The message may be any valid JSON type including objects, arrays, strings, and numbers. | |
channel | String | Yes | Specifies channel name to publish messages to. | |
sendByPost | Boolean | Optional | false | If true the messages sent via POST. |
meta | Object | Optional | Publish extra meta with the request. |
Basic Usage
Fire a message to a channel
try {
const result = await pubnub.fire({
message: {
such: "object",
},
channel: "my_channel",
sendByPost: false, // true to send via post
meta: {
cool: "meta",
}, // fire extra meta with the request
});
console.log("message published w/ timetoken", response.timetoken);
} catch (status) {
// handle error
show all 17 linesOther Examples
Basic usage with Promises
pubnub.fire({
message: {
such: 'object'
},
channel: 'my_channel',
sendByPost: false, // true to send via post
meta: {
"cool": "meta"
} // fire extra meta with the request
}).then((response) => {
console.log(response);
}).catch((error) => {
console.log(error);
});
Signal
The signal()
function is used to send a signal to all subscribers of a channel.
By default, signals are limited to a message payload size of 64
bytes. This limit applies only to the payload, and not to the URI or headers. If you require a larger payload size, please contact support.
Method(s)
To Signal a message
, you can use the following method(s) in the JavaScript SDK:
pubnub.signal({
message: string,
channel: string
}): Promise<SignalResponse>;
Parameter | Type | Required | Description |
---|---|---|---|
Operation Arguments | Hash | Yes | A hash of arguments. |
message | string | Yes | The message may be any valid JSON type including objects, arrays, strings, and numbers. |
channel | string | Yes | Specifies channel name to send messages to. |
Basic Usage
Signal a message to a channel
const result = await pubnub.signal({
message: "hello",
channel: "foo",
});
Response
type SignalResponse = {
timetoken: number
}
Subscribe
The subscribe function creates an open TCP socket to PubNub and begins listening for messages and events on a specified entity or set of entities. To subscribe successfully, you must configure the appropriate subscribeKey
at initialization.
Entities are first-class citizens that provide access to their encapsulated APIs. You can subscribe using the PubNub client object or directly on a specific entity:
A newly subscribed client receives messages after the subscribe()
call completes. You can configure retryConfiguration
to automatically attempt to reconnect and retrieve any available messages if a client gets disconnected.
Subscription scope
Subscription objects provide an interface to attach listeners for various real-time update types. Your app receives messages and events via those event listeners. Two types of subscriptions are available:
subscription
, created from an entity with a scope of only that entity (for example, a particular channel)subscriptionSet
, created from the PubNub client with a global scope (for example, all subscriptions created on a singlepubnub
object ). A subscription set can have one or more subscriptions.
The event listener is a single point through which your app receives all the messages, signals, and events in the entities you subscribed to. For information on adding event listeners, refer to Event listeners.
Create a subscription
An entity-level subscription
allows you to receive messages and events for only that entity for which it was created. Using multiple entity-level subscription
s is useful for handling various message/event types differently in each channel.
// entity-based, local-scoped
const channel = pubnub.channel('channel_1');
channel.subscription(subscriptionOptions)
Parameter | Type | Required | Description |
---|---|---|---|
subscriptionOptions | subscriptionOptions | No | Subscription behavior configuration. |
Create a subscription set
A client-level subscriptionSet
allows you to receive messages and events for all entities in the set. A single subscriptionSet
is useful for similarly handling various message/event types in each channel.
// client-based, general-scoped
pubnub.subscriptionSet({
channels: string[],
channelGroups: string[],
subscriptionOptions: subscriptionOptions
}))
Parameter | Type | Required | Description |
---|---|---|---|
→ channels | string[] | No | Channels to subscribe to. Either channels or channelGroups is mandatory. |
→ channelGroups | string[] | No | Channel groups to subscribe to. Either channels or channelGroups is mandatory. |
→ subscriptionOptions | subscriptionOptions | No | Subscription behavior configuration. |
Add/remove sets
You can add and remove subscription sets to create new sets. Refer to the Other examples section for more information.
subscriptionOptions
subscriptionOptions
is a class. Available properties include:
Option | Type | Description |
---|---|---|
receivePresenceEvents | boolean | Whether presence updates for userId should be delivered through the listener streams. |
cursor | object | Cursor from which to return any available cached messages. Message retrieval with cursor is not guaranteed and should only be considered a best-effort service. A cursor consists of a timetoken and region: cursor?: { timetoken?: string; region?: number } If you pass any primitive type, the SDK converts them into SubscriptionCursor but if their value is not a 17-digit number or a string with numeric characters, the provided value will be ignored. |
Method(s)
subscription
and subscriptionSet
use the same subscribe()
method.
Subscribe
To subscribe, you can use the following method in the JavaScript SDK:
subscription.subscribe()
subscriptionSet.subscribe()
Basic usage
const subscriptionSet = pubnub.subscriptionSet({ channels: ['ch1', 'ch2'] });
subscriptionSet.subscribe();
Other examples
Create a subscription set from 2 individual subscriptions
// create a subscription from a channel entity
const channel = pubnub.channel('channel_1')
const subscription1 = channel.subscription({ receivePresenceEvents: true });
// create a subscription from a channel group entity
const channelGroup = pubnub.channelGroup('channelGroup_1')
const subscription2 = channelGroup.subscription();
// add 2 subscriptions to create a subscription set
const subscriptionSet = subscription1.addSubscription(subscription2);
// add another subscription to the set
const subscription3 = pubnub.channel('channel_3').subscription({ receivePresenceEvents: false });
subscriptionSet.addSubscription(subscription3);
show all 19 linesCreate a subscription set from 2 sets
// create a subscription set with multiple channels
const subscriptionSet1 = pubnub.subscriptionSet({ channels: ['ch1', 'ch2'] });
// create a subscription set with multiple channel groups and options
const subscriptionSet2 = pubnub.subscriptionSet({
channels: ['ch1', 'ch2'],
subscriptionOptions: { receivePresenceEvents: true }
});
// create a new subscription set from 2 sets
const subscriptionSet3 = subscriptionSet1.addSubscriptionSet(subscriptionSet2);
// you can also remove sets
const subscriptionSetWithChannelsOnly = subscriptionSet3.removeSubscriptionSet(subscriptionSet2);
Returns
The subscribe()
method doesn't have a return value.
Entities
Entities are subscribable objects for which you can receive real-time updates (messages, events, etc).
Create channels
This method returns a local channel
entity.
pubnub.channel(string)
Parameter | Type | Required | Description |
---|---|---|---|
channel | string | Yes | The name of the channel to create a subscription of. |
Basic usage
const channel = pubnub.channel('channel_1');
Create channel groups
This method returns a local channelGroup
entity.
pubnub.channelGroup(string)
Parameter | Type | Required | Description |
---|---|---|---|
channel_group | string | Yes | The name of the channel group to create a subscription of. |
Basic usage
const channelGroup = pubnub.channelGroup('channelGroup_1');
Create channel metadata
This method returns a local channelMetadata
entity.
pubnub.channelMetadata(string)
Parameter | Type | Required | Description |
---|---|---|---|
channelMetadata | string | Yes | The String identifier of the channel metadata object to create a subscription of. |
Basic usage
const channelMetadata = pubnub.channelMetadata('channel_1');
Create user metadata
This method returns a local userMetadata
entity.
pubnub.userMetadata(string)
Parameter | Type | Required | Description |
---|---|---|---|
userMetadata | string | Yes | The String identifier of the user metadata object to create a subscription of. |
Basic usage
const userMetadata = pubnub.userMetadata('user_meta1');
Event listeners
Messages and events are received in your app using a listener. This listener allows a single point to receive all messages, signals, and events.
You can attach listeners to the instances of subscription
, subscriptionSet
, and, in the case of the connection status, the PubNub client.
Add listeners
You can implement multiple listeners with the addListener()
method or register an event-specific listener that receives only a selected type, like message
or file
.
Method(s)
// create a subscription from a channel entity
const channel = pubnub.channel('channel_1');
const subscription = channel.subscription();
// Event-specific listeners
subscription.onMessage = (messageEvent) => { console.log("Message event: ", messageEvent); };
subscription.onPresence = (presenceEvent) => { console.log("Presence event: ", presenceEvent); };
subscription.onMessage = (messageEvent) => { console.log("Message event: ", messageEvent); };
subscription.onPresence = (presenceEvent) => { console.log("Presence event: ", presenceEvent); };
subscription.onSignal = (signalEvent) => { console.log("Signal event: ", signalEvent); };
subscription.onObjects = (objectsEvent) => { console.log("Objects event: ", objectsEvent); };
subscription.onMessageAction = (messageActionEvent) => { console.log("Message Action event: ", messageActionEvent); };
subscription.onFile = (fileEvent) => { console.log("File event: ", fileEvent); };
// Generic listeners
show all 77 linesBasic usage
// create a subscription from a channel entity
const channel = pubnub.channel('channel_1')
const subscription1 = channel.subscription({ receivePresenceEvents: true });
// create a subscription set with multiple channels
const subscriptionSet1 = pubnub.subscriptionSet({ channels: ['ch1', 'ch2'] });
// add a status listener
pubnub.addListener({
status: (s) => {console.log('Status', s.category) }
});
// add message and presence listeners
subscription1.addListener({
// Messages
show all 27 linesAdd connection status listener
The PubNub client has a listener dedicated to handling connection status updates.
Client scope
This listener is only available on the PubNub object.
Method(s)
pubnub.addListener({
status: (s) => s.category
})
Basic usage
// add a status listener
pubnub.addListener({
status: (s) => {console.log('Status', s.category) }
});
Returns
The subscription status. For information about available statuses, refer to SDK statuses.
Unsubscribe
Stop receiving real-time updates from a subscription
or a subscriptionSet
.
Method(s)
subscription.unsubscribe()
subscriptionSet.unsubscribe()
Basic Usage
// create a subscription from a channel entity
const channel = pubnub.channel('channel_1')
const subscription1 = channel.subscription({ receivePresenceEvents: true });
// create a subscription set with multiple channels
const subscriptionSet1 = pubnub.subscriptionSet({ channels: ['ch1', 'ch2'] });
subscription1.subscribe();
subscriptionSet1.subscribe();
subscription1.unsubscribe();
subscriptionSet1.unsubscribe();
Returns
None
Unsubscribe All
Stop receiving real-time updates from all data streams and remove the entities associated with them.
Client scope
This method is only available on the PubNub object.
Method(s)
pubnub.unsubscribeAll()
Basic Usage
// create a subscription set with multiple channels
const subscriptionSet1 = pubnub.subscriptionSet({ channels: ['ch1', 'ch2'] });
subscriptionSet1.subscribe();
// create a subscription from a channel entity
const channelGroup = pubnub.channelGroup('channelGroup_1')
const subscription1 = channelGroup.subscription({ receivePresenceEvents: true });
subscription1.subscribe();
pubnub.unsubscribeAll();
Returns
None
Subscribe (deprecated)
Deprecated
This method is deprecated. Use Subscribe instead.
Receive messages
Your app receives messages and events via event listeners. The event listener is a single point through which your app receives all the messages, signals, and events that are sent in any channel you are subscribed to.
For more information about adding a listener, refer to the Event Listeners section.
Description
This function causes the client to create an open TCP socket to the PubNub Real-Time Network and begin listening for messages on a specified channel
. To subscribe to a channel
the client must send the appropriate subscribeKey
at initialization.
By default a newly subscribed client will only receive messages published to the channel after the subscribe()
call completes.
Connectivity notification
You can be notified of connectivity via the listener, on establishing connection the statusEvent.category
returns PNConnectedCategory
.
By waiting for the connect event to return before attempting to publish, you can avoid a potential race condition on clients that subscribe and immediately publish messages before the subscribe
has completed.
Unsubscribing from all channels
Unsubscribing from all channels, and then subscribing to a new channel Y is not the same as subscribing to channel Y and then unsubscribing from the previously-subscribed channel(s). Unsubscribing from all channels resets the last-received timetoken
and thus, there could be some gaps in the subscription that may lead to message loss.
Method(s)
To Subscribe to a channel
, you can use the following method(s) in the JavaScript SDK:
pubnub.subscribe({
channels: Array<string>,
channelGroups: Array<string>,
withPresence: boolean,
timetoken: number
}): Promise<SubscribeResponse>;
Parameter | Type | Required | Default | Description |
---|---|---|---|---|
Operation Arguments | Hash | Yes | A hash of arguments. | |
channels | Array<string> | Yes | Specifies the channels to subscribe to. It is possible to specify multiple channels as a list or as an array. | |
channelGroups | Array<string> | Specifying either channels or channelGroups is mandatory | Specifies the channelGroups to subscribe to. | |
withPresence | boolean | Optional | false | If true it also subscribes to presence instances. |
timetoken | number | Optional | Specifies timetoken from which to start returning any available cached messages. Message retrieval with timetoken is not guaranteed and should only be considered a best-effort service. |
Basic Usage
Subscribe to a channel:
pubnub.subscribe({
channels: ["my_channel"],
});
Event listeners
The response of the call is handled by adding a Listener. Please see the Event Listeners section for more details. Listeners should be added before calling the method.
Returns
The following objects will be returned in the Status Response
Object | Description |
---|---|
category | PNConnectedCategory |
operation | PNSubscribeOperation |
affectedChannels | The channels affected in the operation, of type array. |
subscribedChannels | All the current subscribed channels, of type array. |
affectedChannelGroups | The channel groups affected in the operation, of type array. |
lastTimetoken | The last timetoken used in the subscribe request, of type long. |
currentTimetoken | The current timetoken fetched in the subscribe response, which is going to be used in the next request, of type long. |
{
category: 'PNConnectedCategory',
operation: 'PNSubscribeOperation',
affectedChannels: ['my_channel_1'],
subscribedChannels: ['my_channel_1'],
affectedChannelGroups: [],
lastTimetoken: '14974492380756600',
currentTimetoken: '14974492384874375'
}
The following objects will be returned in the Subscribe Message Response
Object | Description |
---|---|
channel | The channel for which the message belongs. |
subscription | The channel group or wildcard subscription match (if exists). |
timetoken | Publish timetoken . |
message | The payload . |
actualChannel | Deprecated. Use property channel . |
subscribedChannel | Deprecated. Use property subscription . |
{
actualChannel: null,
channel: "my_channel_1",
message: "Hello World!",
publisher: "pn-58e1a647-3e8a-4c7f-bfa4-e007ea4b2073",
subscribedChannel: "my_channel_1",
subscription: null,
timetoken: "14966804541029440"
}
The following objects will be returned in the Presence Response
Object | Description |
---|---|
action | Can be join , leave , state-change or timeout . |
channel | The channel for which the message belongs. |
occupancy | No. of users connected with the channel . |
state | User State. |
subscription | The channel group or wildcard subscription match (if exists) |
timestamp | Current timetoken . |
timetoken | Publish timetoken . |
uuid | UUIDs of users who are connected with the channel . |
{
category: 'PNConnectedCategory',
operation: 'PNSubscribeOperation',
affectedChannels: ['my_channel_1'],
subscribedChannels: ['my_channel_1'],
affectedChannelGroups: [],
lastTimetoken: '14974492380756600',
currentTimetoken: '14974492384874375'
}
Other Examples
Subscribing to multiple channels
It's possible to subscribe to more than one channel using the Multiplexing feature. The example shows how to do that using an array to specify the channel names.
Alternative subscription methods
You can also use Wildcard Subscribe and Channel Groups to subscribe to multiple channels at a time. To use these features, the Stream Controller add-on must be enabled on your keyset in the Admin Portal.
pubnub.subscribe({
channels: ['my_channel_1', 'my_channel_2', 'my_channel_3']
});
Subscribing to a Presence channel
Requires Presence add-on
This method requires that the Presence add-on is enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys.
For any given channel there is an associated Presence channel. You can subscribe directly to the channel by appending -pnpres
to the channel name. For example the channel named my_channel
would have the presence channel named my_channel-pnpres
.
pubnub.subscribe({
channels: ["my_channel"],
withPresence: true,
});
Wildcard subscribe to channels
Requires Stream Controller add-on
This method requires that the Stream Controller add-on is enabled for your key in the Admin Portal (with Enable Wildcard Subscribe checked). Read the support page on enabling add-on features on your keys.
Wildcard subscribes allow the client to subscribe to multiple channels using wildcard. For example, if you subscribe to a.*
you will get all messages for a.b
, a.c
, a.x
. The wildcarded *
portion refers to any portion of the channel string name after the dot (.)
.
pubnub.subscribe({
channels: ["ab.*"],
});
Wildcard grants and revokes
Only one level (a.*
) of wildcarding is supported. If you grant on *
or a.b.*
, the grant will treat *
or a.b.*
as a single channel named either *
or a.b.*
. You can also revoke permissions from multiple channels using wildcards but only if you previously granted permissions using the same wildcards. Wildcard revokes, similarly to grants, only work one level deep, like a.*
.
Subscribing with State
Requires Presence add-on
This method requires that the Presence add-on is enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys.
Required UUID
Always set the UUID
to uniquely identify the user or device that connects to PubNub. This UUID
should be persisted, and should remain unchanged for the lifetime of the user or the device. If you don't set the UUID
, you won't be able to connect to PubNub.
const pubnub = new PubNub({
/* initiation arguments */
});
pubnub.addListener({
status: async (statusEvent) => {
if (statusEvent.category === "PNConnectedCategory") {
try {
await pubnub.setState({
state: {
some: "state",
},
});
} catch (status) {
// handle setState error
show all 29 linesSubscribe to a channel group
Requires Stream Controller add-on
This method requires that the Stream Controller add-on is enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys.
pubnub.subscribe({
channelGroups: ["my_channelGroup"],
});
Subscribe to the presence channel of a channel group
note
This method requires that both the Stream Controller and Presence add-ons are enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys.
pubnub.subscribe({
channelGroups: ["family"],
withPresence: true,
});
Subscribing to multiple channel groups
Requires Stream Controller add-on
This method requires that the Stream Controller add-on is enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys.
pubnub.subscribe({
channelGroups: ["my_channelGroup1", "my_channelGroup2", "my_channelGroup3"],
});
Subscribing to a channel and channel group simultaneously
Requires Stream Controller add-on
This method requires that the Stream Controller add-on is enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys.
pubnub.subscribe({
channels: ["my_channel"],
channelGroups: ["my_channelGroup"],
});
Sample Responses
Join Event
{
"channel": "my_channel",
"subscription": null,
"actualChannel": null,
"subscribedChannel": "my_channel-pnpres",
"action": "join",
"timetoken": "15119466699655811",
"occupancy": 2,
"uuid": "User1",
"timestamp": 1511946669
}
Leave Event
{
"channel": "my_channel",
"subscription": null,
"actualChannel": null,
"subscribedChannel": "my_channel-pnpres",
"action": "leave",
"timetoken": "15119446002445794",
"occupancy": 1,
"uuid": "User1",
"timestamp": 1511944600
}
Timeout Event
{
"channel": "my_channel",
"subscription": null,
"actualChannel": null,
"subscribedChannel": "my_channel-pnpres",
"action": "timeout",
"timetoken": "15119519897494311",
"occupancy": 3,
"uuid": "User2",
"timestamp": 1511951989
}
Custom Presence Event (State Change)
{
"channel": "my_channel",
"subscription": null,
"actualChannel": null,
"subscribedChannel": "my_channel-pnpres",
"action": "state-change",
"state": {
"isTyping": true
},
"timetoken": "15119477895378127",
"occupancy": 5,
"uuid": "User4",
"timestamp": 1511947789
}
Interval Event
{
"action": "interval",
"occupancy": 2,
"timestamp": 1511947739
}
When a channel is in interval mode with presence_deltas
pnconfig
flag enabled, the interval message may also include the following fields which contain an array of changed UUIDs since the last interval message.
- joined
- left
- timedout
For example, this interval message indicates there were 2 new UUIDs that joined and 1 timed out UUID since the last interval:
{
"action":"interval",
"timestamp":1548340678,
"occupancy":2,
"join":["pn-94bea6d1-2a9e-48d8-9758-f1b7162631ed","pn-cecbfbe3-312f-4928-93a2-5a79c91b10e0"]},
"timedout":["pn-cecbfbe3-312f-4928-93a2-5a79c91b10e0"],
"b":"my-channel-pnpres"
}
If the full interval message is greater than 30KB
(since the max publish payload is ∼32KB
), none of the extra fields will be present. Instead there will be a here_now_refresh
boolean field set to true
. This indicates to the user that they should do a hereNow
request to get the complete list of users present in the channel.
{
"channel": "my_channel",
"subscription": null,
"actualChannel": null,
"subscribedChannel": "my_channel-pnpres",
"action": "interval",
"timetoken": "15119477396210903",
"occupancy": 4,
"timestamp": 1511947739,
"here_now_refresh" : true
}
You can be notified of connectivity status, message, and presence notifications via the listeners.
Listeners should be added before calling the method.
Add Listeners
pubnub.addListener({
// Messages
message: function (m) {
const channelName = m.channel; // Channel on which the message was published
const channelGroup = m.subscription; // Channel group or wildcard subscription match (if exists)
const pubTT = m.timetoken; // Publish timetoken
const msg = m.message; // Message payload
const publisher = m.publisher; // Message publisher
},
// Presence
presence: function (p) {
const action = p.action; // Can be join, leave, state-change, or timeout
const channelName = p.channel; // Channel to which the message belongs
const occupancy = p.occupancy; // Number of users subscribed to the channel
const state = p.state; // User state
show all 71 linesRemove Listeners
var existingListener = {
message: function () {
},
};
pubnub.removeListener(existingListener);
Listener status events
Category | Description |
---|---|
PNNetworkUpCategory | The SDK detected that the network is online. |
PNNetworkDownCategory | The SDK announces this when a connection isn't available, or when the SDK isn't able to reach PubNub servers. |
PNNetworkIssuesCategory | A subscribe event experienced an exception when running. The SDK isn't able to reach PubNub servers. This may be due to many reasons, such as the machine or device isn't connected to the internet; the internet connection has been lost; your internet service provider is having trouble; or, perhaps the SDK is behind a proxy. |
PNReconnectedCategory | The SDK was able to reconnect to PubNub. |
PNConnectedCategory | SDK subscribed with a new mix of channels. This is fired every time the channel or channel group mix changes. |
PNAccessDeniedCategory | Access Manager permission failure. |
PNMalformedResponseCategory | JSON parsing crashed. |
PNBadRequestCategory | The server responded with a bad response error because the request is malformed. |
PNDecryptionErrorCategory | If using decryption strategies and the decryption fails. |
PNTimeoutCategory | Failure to establish a connection to PubNub due to a timeout. |
PNRequestMessageCountExceedCategory | The SDK announces this error if requestMessageCountThreshold is set, and the number of messages received from PubNub (in-memory cache messages) exceeds the threshold. |
PNUnknownCategory | Returned when the subscriber gets a non-200 HTTP response code from the server. |
Unsubscribe (deprecated)
Deprecated
This method is deprecated. Use Unsubscribe instead.
When subscribed to a single channel, this function causes the client to issue a leave
from the channel
and close any open socket to the PubNub Network. For multiplexed channels, the specified channel
(s) will be removed and the socket remains open until there are no more channels remaining in the list.
Unsubscribing from all channels
Unsubscribing from all channels, and then subscribing to a new channel Y is not the same as subscribing to channel Y and then unsubscribing from the previously-subscribed channel(s). Unsubscribing from all channels resets the last-received timetoken
and thus, there could be some gaps in the subscription that may lead to message loss.
Method(s)
To Unsubscribe from a channel
, you can use the following method(s) in the JavaScript SDK:
pubnub.unsubscribe({
channels: Array<string>,
channelGroups: Array<string>
}): Promise<UnsubscribeResponse>;
Parameter | Type | Required | Description |
---|---|---|---|
Operation Arguments | Hash | Yes | A hash of arguments. |
channels | Array<string> | Yes | Specifies the channel to unsubscribe from. |
channelGroups | Array<string> | Specifying either channels or channelGroups is mandatory | Specifies the channelGroups to unsubscribe from. |
Basic Usage
Unsubscribe from a channel:
pubnub.unsubscribe({
channels: ["my_channel"],
});
Response
The output below demonstrates the response to a successful call:
{
"action" : "leave"
}
Other Examples
Unsubscribing from multiple channels
Requires Stream Controller add-on
This method requires that the Stream Controller add-on is enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys.
pubnub.unsubscribe({
channels: ["chan1", "chan2", "chan3"],
});
Example Response
{
"action" : "leave"
}
Unsubscribing from multiple channel groups
Requires Stream Controller add-on
This method requires that the Stream Controller add-on is enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys.
pubnub.unsubscribe({
channelGroups: ["demo_group1", "demo_group2"],
});
Unsubscribe All (deprecated)
Deprecated
This method is deprecated. Use Unsubscribe all instead.
Unsubscribe from all channels and all channel groups
Method(s)
unsubscribeAll()
Basic Usage
pubnub.unsubscribeAll();
Returns
None