The foundation of the PubNub service is the ability to send a message and have it delivered anywhere in less than 30ms. 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 patternsPubNub 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() sends a message to all channel subscribers. A successfully published message is replicated across PubNub's points of presence and sent simultaneously to all subscribed clients on a channel.
publishKey.You can secure the messages with SSL/TLS by setting ssl to true during initialization. You can also encrypt messages.
The message can contain any JSON-serializable data (Objects, Arrays, Ints, Strings) and shouldn't contain any special classes or functions. String content can include any single-byte or multi-byte UTF-8 characters.
Don't JSON serializeYou should not JSON serialize the message and meta parameters when sending signals, messages, or files as the serialization is automatic. Pass the full object as the message/meta payload and let PubNub handle everything.
The maximum message size is 32 KiB, including the final escaped character count and the channel name. An optimal message size is under 1800 bytes.
If the message you publish exceeds the configured size, you receive a Message Too Large error. If you want to learn more or calculate your payload size, refer to Message Size Limit.
You can publish as fast as bandwidth conditions 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, the subscriber may not receive the first 100 messages because the message queue has a limit of only 100 messages stored in memory.
You can optionally provide the customMessageType parameter to add your business-specific label or category to the message, for example text, action, or poll.
[1,"Sent","136074940..."])[0,"blah","<timetoken>"]), retry the publish.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,
customMessageType: string
}): Promise<PublishResponse>;
* required
Parameter Descriptionmessage *
Type: any
Default:
n/a
Themessage may be any valid JSON type including objects, arrays, strings, and numbers. channel *
Type: string
Default:
n/a
Specifies thechannel ID to publish messages to. storeInHistory
Type: boolean
Default:
true
true the messages are stored in history.
storeInHistory is not specified, then the history configuration on the key is used. sendByPost
Type: boolean
Default:
false
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
Type: any
Default:
n/a
Publish extrameta with the request. ttl
Type: number
Default:
n/a
Set a per message time to live in Message Persistence.storeInHistory = true, and ttl = 0, the message is stored with no expiry time.storeInHistory = true and ttl = X (X is an Integer value), the message is stored with an expiry time of X hours unless you have message retention set to Unlimited on your keyset configuration in the Admin Portal.storeInHistory = false, the ttl parameter is ignored.ttl is not specified, then expiration of the message defaults back to the expiry value for the key.customMessageType
Type: string
Default:
n/a
A case-sensitive, alphanumeric string from 3 to 50 characters describing the business-specific label or category of the message. Dashes- and underscores _ are allowed. The value cannot start with special characters or the string pn_ or pn-.
Examples: text, action, poll.
This example is a self-contained code snippet ready to be run. It includes necessary imports and executes methods with console logging. Use it as a reference when working with other examples in this document.
Publish a message to a channel Subscribe to the channelBefore 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.
Responsetype PublishResponse = {
timetoken: number
}
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.
To Fire a message, you can use the following method(s) in the JavaScript SDK:
fire({
Object message,
String channel,
Boolean sendByPost,
Object meta
})
* required
Parameter Descriptionmessage *
Type: Object
Default:
n/a
Themessage may be any valid JSON type including objects, arrays, strings, and numbers. channel *
Type: String
Default:
n/a
Specifieschannel ID to publish messages to. sendByPost
Type: Boolean
Default:
false
true the messages sent via POST. meta
Type: Object
Default:
n/a
Publish extrameta with the request. Sample code Fire a message to a channel 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.
To Signal a message, you can use the following method(s) in the JavaScript SDK:
pubnub.signal({
message: string,
channel: string,
customMessageType: string,
}): Promise<SignalResponse>;
* required
Parameter Descriptionmessage *
Type: string
Themessage may be any valid JSON type including objects, arrays, strings, and numbers. channel *
Type: string
Specifieschannel ID to send messages to. customMessageType
Type: string
A case-sensitive, alphanumeric string from 3 to 50 characters describing the business-specific label or category of the message. Dashes- and underscores _ are allowed. The value cannot start with special characters or the string pn_ or pn-.
Examples: text, action, poll.
type SignalResponse = {
timetoken: number
}
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.
For more general information about subscriptions, refer to Subscriptions.
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.
Calling subscribe() opens a connection but doesn't deliver messages to your code. You must also add event listeners to receive messages and access sender information. The message object received through listeners includes the sender's ID in the publisher field.
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 single pubnub 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.
Add subscriptions to an existing setIf you subscribe to a subscription set and then add more subscriptions to it, they are automatically subscribed to.
Create a subscriptionAn entity-level subscription allows you to receive messages and events for only that entity for which it was created. Using multiple entity-level subscriptions is useful for handling various message/event types differently in each channel.
const channel = pubnub.channel('channel_1');
channel.subscription(subscriptionOptions)
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.
pubnub.subscriptionSet({
channels: string[],
channelGroups: string[],
subscriptionOptions: subscriptionOptions
}))
* required
Parameter Description →channels
Type: string[]
channels or channelGroups is mandatory. → channelGroups
Type: string[]
channels or channelGroups is mandatory. → subscriptionOptions
Type: subscriptionOptions
Subscription behavior configuration. subscriptionOptions
subscriptionOptions is a class. Available properties include:
receivePresenceEvents boolean Whether presence updates for userIds should be delivered through the listener streams.
For information on how to receive presence events and what those events are, refer to Presence Events.
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.
You can add and remove subscriptions to and from an existing set to create new sets. If you subscribe to a subscription set and then add more subscriptions to it, they are automatically subscribed to.
Refer to the Other examples section for more information on adding and removing subscriptions.
Method(s)subscription and subscriptionSet use the same subscribe() method.
To subscribe, you can use the following method in the JavaScript SDK:
subscription.subscribe()
subscriptionSet.subscribe()
Wildcard subscribe (e.g., sports.*) works the same as regular subscribe - you still need to add event listeners to receive messages. The message objects received include the sender's ID in the publisher field, the actual channel name in the channel field, and the wildcard match in the subscription field.
The subscribe() method doesn't have a return value.
Entities are subscribable objects for which you can receive real-time updates (messages, events, etc).
Create channelsThis method returns a local channel entity.
* required
Parameter Descriptionchannel *
Type: string
This method returns a local channelGroup entity.
pubnub.channelGroup(string)
* required
Parameter Descriptionchannel_group *
Type: string
This method returns a local channelMetadata entity.
pubnub.channelMetadata(string)
* required
Parameter DescriptionchannelMetadata *
Type: string
This method returns a local userMetadata entity.
pubnub.userMetadata(string)
* required
Parameter DescriptionuserMetadata *
Type: string
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.
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.
When you receive messages through listeners, the message object includes the sender's ID in the publisher field, along with the message content, channel name, timetoken, and other metadata.
The PubNub client has a listener dedicated to handling connection status updates.
Client scopeThis listener is only available on the PubNub object.
Method(s) Sample code ReturnsThe subscription status. For information about available statuses, refer to SDK statuses.
UnsubscribeStop receiving real-time updates from a subscription or a subscriptionSet.
subscription.unsubscribe()
subscriptionSet.unsubscribe()
None
Unsubscribe allStop receiving real-time updates from all data streams and remove the entities associated with them.
Client scopeThis method is only available on the PubNub object.
Method(s) Sample code ReturnsNone
Subscribe (old) Not recommendedThe use of this method is discouraged. Use Subscribe instead.
Receive messagesYour 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.
DescriptionThis 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 ID 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.
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, 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.
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>;
* required
Parameter Descriptionchannels *
Type: Array<string>
:
n/a
Specifies thechannels to subscribe to. It is possible to specify multiple channels as a list or as an array. channelGroups
Type: Array<string>
:
n/a
Specifies thechannelGroups to subscribe to. withPresence
Type: boolean
Default:
false
true it also subscribes to presence instances. timetoken
Type: number
Default:
n/a
Specifiestimetoken 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. Sample code
Subscribe to a channel:
Event listenersThe 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 Descriptioncategory 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'
}
channel The channel ID 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"
}
action Can be join, leave, state-change or timeout. channel The channel ID for which the message belongs. occupancy No. of users connected with the channel ID. 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 ID.
{
category: 'PNConnectedCategory',
operation: 'PNSubscribeOperation',
affectedChannels: ['my_channel_1'],
subscribedChannels: ['my_channel_1'],
affectedChannelGroups: [],
lastTimetoken: '14974492380756600',
currentTimetoken: '14974492384874375'
}
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 methodsYou 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.
Subscribing to a Presence channel Requires PresenceThis method requires that the Presence add-on is enabled for your key in the Admin Portal.
For information on how to receive presence events and what those events are, refer to Presence Events.
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.
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 (.).
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.*.
This method requires that the Presence add-on is enabled for your key in the Admin Portal.
For information on how to receive presence events and what those events are, refer to Presence Events.
Required UUIDAlways 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.
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.
Subscribe to the presence channel of a channel group Requires Stream Controller and Presence add-onsThis 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.
Subscribing to multiple channel groups Requires Stream Controller add-onThis 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.
Subscribing to a channel and channel group simultaneously Requires Stream Controller add-onThis 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.
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
}
{
"channel": "my_channel",
"subscription": null,
"actualChannel": null,
"subscribedChannel": "my_channel-pnpres",
"action": "leave",
"timetoken": "15119446002445794",
"occupancy": 1,
"uuid": "User1",
"timestamp": 1511944600
}
{
"channel": "my_channel",
"subscription": null,
"actualChannel": null,
"subscribedChannel": "my_channel-pnpres",
"action": "timeout",
"timetoken": "15119519897494311",
"occupancy": 3,
"uuid": "User2",
"timestamp": 1511951989
}
{
"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
}
{
"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.
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 listenerspubnub.addListener({
message: function (m) {
const channelName = m.channel;
const channelGroup = m.subscription;
const pubTT = m.timetoken;
const msg = m.message;
const publisher = m.publisher;
},
presence: function (p) {
const action = p.action;
const channelName = p.channel;
const occupancy = p.occupancy;
var existingListener = {
message: function () {
},
};
pubnub.removeListener(existingListener);
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 (old) Not recommended
The use of this method is discouraged. 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, 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.
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>;
* required
Parameter Descriptionchannels *
Type: Array<string>
channel ID to unsubscribe from. channelGroups
Type: Array<string>
channelGroups to unsubscribe from. Sample code
Unsubscribe from a channel:
ResponseThe output below demonstrates the response to a successful call:
Other examples Unsubscribing from multiple channels Requires Stream Controller add-onThis 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.
Example response Unsubscribing from multiple channel groups Requires Stream Controller add-onThis 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.
Unsubscribe all (old) Not recommendedThe use of this method is discouraged. Use Unsubscribe all instead.
Unsubscribe from all channels and all channel groups
Method(s) Sample code ReturnsNone
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