Publish/Subscribe API for PubNub PHP 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.

Publish

Description

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 PHP V4 classes or functions as these will not serialize. String content can include any single-byte or multi-byte UTF-8 character.

Don't JSON serialize

It is important to note that you should not JSON serialize 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 Calculating Message Payload Size Before Publish.

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 PHP V4 SDK:

$pubnub->publish()->channel(string)->message(string|array)->shouldStore(boolean)->meta(array)->usePost(boolean)->sync();
ParameterTypeRequiredDefaultDescription
channelStringYesDestination of message.
messageString|ArrayYesThe payload.
shouldStoreBooleanOptionalaccount defaultStore in history.
metaArrayOptionalnullMeta data object which can be used with the filtering ability.
usePostBooleanOptionalfalseUse POST to publish.

Basic Usage

Publish a message to a channel

$result = $pubnub->publish()
->channel("my_channel")
->message(["hello", "there"])
->usePost(true)
->sync();
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

The publish() operation returns a PNPublishResult which contains the following fields:

Property NameTypeDescription
getTimetoken()IntegerAn integer representation of the timetoken when the message was published.

Other Examples

Publish with metadata

$result = $pubnub->publish()
->channel("my_channel")
->message(["hello", "there"])
->meta(["name" => "Alex"])
->sync();

Publish Array

use PubNub\Exceptions\PubNubException;

try {
$result = $pubnub->publish()
->channel("my_channel")
->message(["hello", "there"])
->meta(["name" => "Alex", "online" => true])
->sync();
print_r($result->getTimetoken());
} catch (PubNubException $error) {
handleException($error);
}

Fire

Description

The fire endpoint allows the client to send a message to PubNub Functions Event Handlers. 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 PHP V4 SDK:

$pubnub->fire()->channel(string)->message(string|array)->meta(array)->usePost(boolean)->sync();
ParameterTypeRequiredDefaultDescription
channelStringYesDestination of message.
messageString|ArrayYesThe payload.
metaArrayOptionalnullMeta data object which can be used with the filtering ability.
usePostBooleanOptionalfalseUse POST to publish.

Basic Usage

Fire a message to a channel

use PubNub\Exceptions\PubNubException;

try {
$result = $pubnub->fire()
->channel("my_channel")
->message(["hello","there"])
->usePost(true)
->sync();

echo "Publish worked! Timetoken: " . $result->getTimetoken();
}
catch(\PubNub\Exceptions\PubNubServerException $e) {
echo "Error happened while publishing: " . $e->getMessage();
}

Subscribe

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.

Subscribe call is blocking and it will block until:
  • A message is published on the channel(s) it is subscribed to (message callback).
  • A presence event is received on the channel(s) it is subscribed to (presence callabck).
  • A status event is triggered by SDK (status callback).

Inside of all of the callbacks above you can throw PubNubUnsubscribeException to exit the subscribe loop.

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 PHP V4 SDK:

$pubnub->subscribe()->channels(string|array)->channelGroups(string|array)->withTimetoken(integer)->withPresence(boolean)->execute();
ParameterTypeRequiredDescription
channelsString or ArrayOptionalSubscribe to channels, Either channel or channel_group is required.
channelGroupsString or ArrayOptionalSubscribe to channel_groups, Either channel or channel_group is required.
withTimetokenIntegerOptionalPass a timetoken.
withPresenceBooleanOptionalAlso subscribe to related presence information.

Basic Usage

Subscribe to a channel:

$pubnub->subscribe()
->channels("my_channel")
->execute();
Event listeners

The response of the call is handled by adding a Listener. Please see the Listeners section for more details. Listeners should be added before calling the method.

Response

PNStatus:

Property NameTypeDescription
getCategory()PNStatusCategoryDetails of StatusCategory are here
isError()boolThis is true if an error occurred in the execution of the operation.
getException()PubNubExceptionError data of the exception (if Error is true).
getStatusCode()intStatus code of the execution.
OperationOperationTypeOperation type of the request.

PNMessageResult:

MethodTypeDescription
getMessage()ObjectThe message sent on channel.
getSubscription()StringThe channel on which the message was received.
getTimetoken()IntegerTimetoken for the message.

PNPresenceEventResult:

MethodTypeDescription
getStatusCode()IntegerEvents like join, leave, timeout, state-change.
getUuid()Stringuuid for event.
getTimestamp()Integertimestamp for event.
getOccupancy()IntegerCurrent occupancy.
getSubscription()StringMessage has been received on channel.
getTimetoken()Integertimetoken of the message.

Other Examples

Basic subscribe with logging

use Monolog\Handler\ErrorLogHandler;
use PubNub\PNConfiguration;
use PubNub\PubNub;

$pnconf = new PNConfiguration();

$pnconf->setPublishKey("demo");
$pnconf->setSubscribeKey("demo");

$pubnub = new PubNub($pnconf);

$pubnub->getLogger()->pushHandler(new ErrorLogHandler());

$pubnub->subscribe()->channels("my_channel")->execute();

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_channel1", "my_channel2"])
->execute();

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()
->execute();

Sample Responses

Join Event
{
"action": "join",
"timestamp": 1345546797,
"uuid": "175c2c67-b2a9-470d-8f4b-1db94f90e39e",
"occupancy": 2
}
Leave Event
{
"action" : "leave",
"timestamp" : 1345549797,
"uuid" : "175c2c67-b2a9-470d-8f4b-1db94f90e39e",
"occupancy" : 1
}
Timeout Event
{
"action": "timeout",
"timestamp": 1345549797,
"uuid": "76c2c571-9a2b-d074-b4f8-e93e09f49bd",
"occupancy": 0
}
ustom Presence Event (State Change)
{
"action": "state-change",
"uuid": "76c2c571-9a2b-d074-b4f8-e93e09f49bd",
"timestamp": 1345549797,
"data": {
"isTyping": true
}
}
Interval Event
{
"action":"interval",
"timestamp":1474396578,
"occupancy":2
}

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",
"occupancy" : <# users in channel>,
"timestamp" : <unix timestamp>,
"joined" : ["uuid2", "uuid3"],
"timedout" : ["uuid1"]
}

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.

{
"action" : "interval",
"occupancy" : <# users in channel>,
"timestamp" : <unix timestamp>,
"here_now_refresh" : 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("foo.*")
->execute();
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.

use PubNub\PubNub;
use PubNub\PNConfiguration;
use PubNub\Callbacks\SubscribeCallback;

$pnconf = new PNConfiguration();

$pnconf->setPublishKey("demo");
$pnconf->setSubscribeKey("demo");

$pubnub = new PubNub($pnconf);

class MySubscribeCallback extends SubscribeCallback {
function status($pubnub, $status) {
if ($status->getCategory() === PNStatusCategory::PNConnectedCategory) {
$result = $pubnub->setState()
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Subscribe 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(["cg1", "cg2"])
->execute();

Subscribe to the presence channel of a channel group

Requires Stream Controller and Presence add-ons

This method requires 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("awesome_channel_group")
->withPresence()
->execute();

Unsubscribe

Description

To unsubscribe you should throw PubNubUnsubscribeException somewhere inside status/message/presence callbacks of your subscribe listeners. You should specify channel and / or channel group names to unsubscribe and keep a subscription loop running if some other channels left. Otherwise the exception will unsubscribe from all channels and channel-groups.

Method(s)

To Unsubscribe from a channel you can use the following method(s) in the PHP V4 SDK:

(new PubNubUnsubscribeException())->setChannels(array)->setChannelGroups(array);
ParameterTypeRequiredDefaultDescription
getChannelsStringOptionalfalseThe channels to get the here now details.
getChannelGroupsStringOptionalfalseThe channel groups to get the here now details.
setChannelsArrayOptionalfalseUnsubscribe to channels, Either channel or channelGroup is required.
setChannelGroupsArrayOptionalfalseUnsubscribe to channel groups, Either channel or channelGroup is required.

Basic Usage

Unsubscribe from a channel:

use PubNub\Callbacks\SubscribeCallback;
use PubNub\Enums\PNStatusCategory;
use PubNub\PNConfiguration;
use PubNub\PubNub;
use PubNub\Exceptions\PubNubUnsubscribeException;

$pnconfig = new PNConfiguration();

$pnconfig->setPublishKey("demo");
$pnconfig->setSubscribeKey("demo");

$pubnub = new PubNub($pnconfig);

class MySubscribeCallback extends SubscribeCallback {
function status($pubnub, $status) {
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Rest Response from Server

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.

use PubNub\Callbacks\SubscribeCallback;
use PubNub\Exceptions\PubNubUnsubscribeException;

class MySubscribeCallback extends SubscribeCallback {
function status($pubnub, $status) {
throw new PubNubUnsubscribeException();
}

function message($pubnub, $message) {
}

function presence($pubnub, $presence) {
}
}
Example Response
{
"action" : "leave"
}

Unsubscribe from a channel group

use PubNub\Callbacks\SubscribeCallback;
use PubNub\Exceptions\PubNubUnsubscribeException;

class MySubscribeCallback extends SubscribeCallback {
function status($pubnub, $status) {
throw (new PubNubUnsubscribeException())->setChannelGroups(["my_channel"]);
}

function message($pubnub, $message) {
}

function presence($pubnub, $presence) {
}
}
Example Response
{
"action": "leave"
}
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