Connection

The Channels connection is the fundamental means of communication with the service. It is a bi-directional connection and is able to receive messages as well as emit messages from the server.

∞ Connecting to Channels

When you create a new Pusher object you are automatically connected to Channels.

var pusher = new Pusher("APP_KEY", options);

∞ Parameters

∞ applicationKeyString Required

The application key is a string which is globally unique to your application. It can be found in the API Access section of your application within the Channels user dashboard.

∞ optionsObject Optional

See Channels options parameter below.

∞ Channels ‘options’ parameter

The options parameter on the Pusher constructor is an optional parameter used to apply configuration on a newly created Pusher instance.

{
  cluster: 'APP_CLUSTER',
  forceTLS: true,
  userAuthentication: {
    params: {
      param1: 'value1',
      param2: 'value2'
    },
    headers: {
      header1: 'value1',
      header2: 'value2'
    }
  }
  channelAuthorization: {
    params: {
      param1: 'value1',
      param2: 'value2'
    },
    headers: {
      header1: 'value1',
      header2: 'value2'
    }
  }
}

The options are:

∞ forceTLSBoolean

It’s possible to define if the connection should be made over TLS. For more information see Encrypting connections

∞ userAuthenticationObject

Object containing the configuration for user authentication. Valid keys are endpoint, transport, params, headers, and customHandler.

Default values are:

var pusher = new Pusher("app_key", {
  userAuthentication: {
    endpoint: "/pusher/user-auth",
    transport: "ajax",
    params: {},
    headers: {},
    customHandler: null,
  },
});

∞ userAuthentication.endpointString

Endpoint on your server that will return the authentication signature needed for private and presence channels. Defaults to '/pusher/user-auth'.

For more information see the authenticating users docs.

If authentication fails a pusher:error event is triggered on the channel. For more information see handling authentication problems.

∞ userAuthentication.transportString

Defines how the authentication endpoint, defined using userAuthentication.endpoint, will be called. There are two options available:

• ajax - The default option where an XMLHttpRequest object will be used to make a request. The parameters will be passed as POST parameters.
• jsonp - The authentication endpoint will be called by a <script> tag being dynamically created pointing to the endpoint defined by userAuthentication.endpoint. This can be used when the authentication endpoint is on a different domain to the web application. The endpoint will therefore be requested as a GET and parameters passed in the query string.

For more information see the authenticating users docs.

∞ userAuthentication.paramsObject

Additional parameters to be sent when the user authentication endpoint is called. When using ajax authentication the parameters are passed as additional POST parameters. When using jsonp authentication the parameters are passed as GET parameters. This can be useful with web application frameworks that guard against CSRF (Cross-site request forgery).

∞ userAuthentication.headersObject

Only applied when using ajax as authentication transport

Provides the ability to pass additional HTTP Headers to the user authentication endpoint. This can be useful with some web application frameworks that guard against CSRF CSRF (Cross-site request forgery).

var pusher = new Pusher("app_key", {
  userAuthentication: {
    headers: {
      "X-CSRF-Token": "some_csrf_token",
    },
  },
});

∞ UserAuth.customHandlerFunction

When present, this function is called instead of a request being made to the endpoint specified by `userAuthentication.endpoint’.

The function gets two parameters:

• An object with a socketId property with a string value
• A callback function that takes two arguments
  • An error value or null
  • An object with the following fields or null
    • auth: String
    • user_data: Optional String

For more information check authenticating users.

∞ channelAuthorizationObject

Object containing the configuration for user authorization. Valid keys are endpoint, transport, params, headers, and customHandler.

Default values are:

var pusher = new Pusher("app_key", {
  channelAuthorization: {
    endpoint: "/pusher/auth",
    transport: "ajax",
    params: {},
    headers: {},
    customHandler: null,
  },
});

∞ channelAuthorization.endpointString

Endpoint on your server that will return the authorization signature needed for private and presence channels. Defaults to '/pusher/auth'.

For more information see the authorizing users docs.

If authorization fails a subscription_error event is triggered on the channel. For more information see handling authorization problems.

∞ channelAuthorization.transportString

Defines how the authorization endpoint, defined using channelAuthorization.endpoint, will be called. There are two options available:

• ajax - The default option where an XMLHttpRequest object will be used to make a request. The parameters will be passed as POST parameters.
• jsonp - The authorization endpoint will be called by a <script> tag being dynamically created pointing to the endpoint defined by channelAuthorization.endpoint. This can be used when the authorization endpoint is on a different domain to the web application. The endpoint will therefore be requested as a GET and parameters passed in the query string.

For more information see the authorizing users docs.

∞ channelAuthorization.paramsObject

Additional parameters to be sent when the channel authorization endpoint is called. When using ajax authorization the parameters are passed as additional POST parameters. When using jsonp authorization the parameters are passed as GET parameters. This can be useful with web application frameworks that guard against CSRF (Cross-site request forgery).

∞ channelAuthorization.headersObject

Only applied when using ajax as authorization transport

Provides the ability to pass additional HTTP Headers to the channel authorization endpoint when authorizing a channel. This can be useful with some web application frameworks that guard against CSRF CSRF (Cross-site request forgery).

var pusher = new Pusher("app_key", {
  channelAuthorization: {
    headers: {
      "X-CSRF-Token": "some_csrf_token",
    },
  },
});

∞ channelAuthorization.customHandlerFunction

When present, this function is called instead of a request being made to the endpoint specified by `channelAuthorization.endpoint’.

The function gets two parameters:

• An object with socketId and channelName properties with string values
• A callback function that takes two arguments
  • An error value or null
  • An object with the following fields or null
    • auth: String
    • channel_data: Optional String
    • shared_secret: Optional String

For more information check authorizing users.

∞ clusterString Required

The identifier of the cluster your application was created in. When not supplied, will connect to the mt1 (us-east-1) cluster.

// will connect to the 'eu' cluster
var pusher = new Pusher("app_key", { cluster: "eu" });

This parameter is mandatory when the app is created in a any cluster except mt1 (us-east-1). Read more about configuring clusters.

∞ disableStatsBoolean

Disables stats collection, so that connection metrics are not submitted to Pusher’s servers.

∞ enabledTransportsArray

Specifies which transports should be used by Channels to establish a connection. Useful for applications running in controlled, well-behaving environments. Available transports: ws, wss, xhr_streaming, xhr_polling, sockjs. Additional transports may be added in the future and without adding them to this list, they will be disabled.

∞ disabledTransportsArray

Specifies which transports must not be used by Channels to establish a connection. Useful for applications running in controlled, well-behaving environments. Available transports: ws, wss, xhr_streaming, xhr_polling, sockjs. Additional transports may be added in the future and without adding them to this list, they will be disabled.

∞ wsHost, wsPort, wssPort, httpHost, httpPort, httpsPortBoolean

These can be changed to point to alternative Channels URLs (used internally for our staging server).

∞ ignoreNullOriginBoolean

Ignores null origin checks for HTTP fallbacks. Use with care, it should be disabled only if necessary (i.e. PhoneGap).

∞ activityTimeoutInteger

After this time (in milliseconds) without any messages received from the server, a ping message will be sent to check if the connection is still working. Default value is supplied by the server, low values will result in unnecessary traffic.

∞ pongTimeoutInteger

After sending a ping message to the server, the client waits pongTimeout milliseconds for a response before assuming the connection is dead and closing it. Default value is supplied by the server.

∞ TLS connections

A Channels client can be configured to only connect over TLS connections. An application that uses TLS should use this option to ensure connection traffic is encrypted. It is also possible to force connections to use TLS by enabling the Force TLS setting within an application’s dashboard settings.

The option to force TLS is available on all plans.

var pusher = new Pusher("app_key", { forceTLS: true });

∞ Detecting Connection Limits

Connection limits are currently only strictly enforced on Sandbox plans. In practical terms this means that when you hit your connection limits and you’re on a Sandbox plan then you will be limited immediately. If you’re on a paid plan then we will not hard limit you until you’ve reached 120% of your plan’s connection limits. You will receive an email if your account exceeds your connection limit. If you are on a Sandbox plan and want to avoid connection limits upgrade your account. For more information on plan limits see pricing.

When connection limits are reached additional connections over the limit will be rejected. You can capture the rejection by binding to the error event on the pusher.connection object.

var pusher = new Pusher("app_key");
pusher.connection.bind("error", function (err) {
  if (err.error.data.code === 4004) {
    log(">>> detected limit error");
  }
});

∞ Disconnecting from Channels

It is also possible to disconnect from Channels.

pusher.disconnect();

Connections automatically close when a user navigates to another web page or closes their web browser so there is no need to do this manually.

∞ Connection States

When working with our Channels client library, you can monitor the state of the connection so that you can notify users about expected behaviour.

This document refers to version 1.9.0 of our library and above. Previous versions used the following events which have now been removed: pusher:connection_established and pusher:connection_failed.

There are multiple ways to use the connection state API:

• Bind to individual state change events
• Bind to all state change events
• Query the state directly

Additionally, the reconnect mechanism is now more transparent. This means that you can display messages that tell the user when the service might be connected.

∞ Available states

You can access the current state as pusher.connection.state and bind to a state change using pusher.connection.bind('connected', function() {...})

∞ Example state changes

Given a supported browser and functioning internet connection, the following states are expected:

initialized -> connecting -> connected

Temporary failure of the Channels connection will cause

connected -> connecting -> connected

If an internet connection disappears

connected -> connecting -> unavailable (after ~ 30s)

When the internet connection becomes available again

unavailable -> connected

In the case that Channels is not supported:

initialized -> failed

∞ Binding to connection events

Each Channels instance now has a connection object which manages the current state of the Channels connection and allows binding to state changes:

var pusher = new Pusher("_APP_KEY");

pusher.connection.bind("connected", function () {
  $("div#status").text("Realtime is go!");
});

You can also bind to the error event, which is emitted whenever a connection error occurs:

pusher.connection.bind("error", function (error) {
  console.error("connection error", error);
  $("div#status").text("Error!");
});

∞ Binding to all state changes

There’s an extra state_change utility event that fires for all state changes:

pusher.connection.bind("state_change", function (states) {
  // states = {previous: 'oldState', current: 'newState'}
  $("div#status").text("Channels current state is " + states.current);
});

∞ Querying the connection state

const state = pusher.connection.state;