Classes

• StreamHub
• StreamHub.ConnectionListener
• StreamHub.ElementLogger

Class StreamHub

The main class for connecting to a StreamHub Push Server and subscribing to topics.

var hub = new StreamHub();

// Example - creating and adding a connection listener
var connectionListener = new StreamHub.ConnectionListener();
connectionListener.onConnectionEstablished = function () {
    alert("Connection up");
};
connectionListener.onConnectionLost = function () {
    alert("Connection down");
};
var hub = new StreamHub();
hub.addConnectionListener(connectionListener);

Parameters:

{Object} oConnectionListener

The connection listener to add. It must implement Streamhub.ConnectionListener.

See:

StreamHub.ConnectionListener

// Example - Connecting to a localhost server:
var hub = new StreamHub();
hub.connect("http://localhost:7979/");

// Example - Serving the data from a subdomain
var hub = new StreamHub();
hub.connect("http://push.server.com/");

// Example - Using a cross-domain proxy
var hub = new StreamHub();
hub.connect("http://www.server.com/proxy.php?request=");

// Example - Configuring a single failover server
var hub = new StreamHub();
hub.connect({
    serverList:         ["http://primary.example.com/",
                         "http://backup.example.com/"],
    failoverAlgorithm:  "priority"
});

// Example - Configuring reconnection behaviour
var hub = new StreamHub();
hub.connect({
    serverList:                   ["http://primary.example.com/"],
    initialReconnectDelayMillis:  500,
    maxReconnectDelayMillis:      30000,
    maxReconnectAttempts:         10,       
    useExponentialBackOff:        true,
    backOffMultiplier:            2   
});

// Example - All failover and configuration options
var hub = new StreamHub();
hub.connect({
    serverList:                   ["https://push1.example.com/",
                                   "https://push2.example.com/",
                                   "https://push3.example.com/"],
    failoverAlgorithm:            "random",
    initialReconnectDelayMillis:  1000,
    maxReconnectDelayMillis:      60000,
    maxReconnectAttempts:         -1,       // no maximum
    useExponentialBackOff:        true,
    backOffMultiplier:            2   
});

Parameters:

{String|Object} config

The URL of the server to connect to e.g. http://localhost:7979/ as a string. Or an object specifying detailed configuration options. Note: The trailing slash is required on all URLs.

{String[]} config.serverList Optional

A list of server URLs e.g. ["http://primary.example.com/","http://backup.example.com/"]

{Number} config.initialReconnectDelayMillis Optional, Default: 1000

How long to wait before the first reconnect attempt (in ms)

{Number} config.maxReconnectDelayMillis Optional, Default: -1

The maximum amount of time we ever wait between reconnect attempts (in ms)

{Number} config.maxReconnectAttempts Optional, Default: -1

This is the maximum number of reconnect attempts. A value of -1 indicates there is no maximum.

{Boolean} config.useExponentialBackOff Optional, Default: false

Should an exponential backoff be used between reconnect attempts

{Number} config.backOffMultiplier Optional, Default: 1

The exponent used in the exponential backoff attempts

{String} config.failoverAlgorithm Optional, Default: ordered

The algorithm used to pick a server from the serverList. Either "ordered" for a traversal from the current server in the list to the bottom, "random" for a random pick, or "priority" to always attempt from the top server in the list to the bottom.

{String} config.connectionType Optional, Default: STREAM

The connection type to prefer. Either StreamHub.POLLING_CONNECTION for polling or StreamHub.STREAMING_CONNECTION for streaming.

{String} config.staticUID Optional

Use a static UID instead of a generated one.

hub.disconnect();

// Example - publishing a chat message
hub.publish("ChatRoom", "{'nickname':'Chatty','message':'Hi room!'}");

// Example - sending a trade
hub.publish("channels.trade", "{'symbol':'GOOG','side':'bid','price':'451.14','amount':'1000'}");

Parameters:

{String} sTopic

The topic to publish the data on

{String} sJson

A string of JSON containing the data to publish

var oLogger = new StreamHub.ElementLogger({elementId : "logMessages"});
hub.setLogger(oLogger);

Parameters:

{Object} oLogger

The logger to set. A logger is required to have one method, called log which takes a String.

See:

StreamHub.ElementLogger

// Example - subscribing to a single topic
function updateListener(sTopic, oData) {
    // ...
}
hub.subscribe("Topic", updateListener);

// Example - subscribing to multiple topics
function updateListener(sTopic, oData) {
    // ...
}
hub.subscribe(["Topic-1", "Topic-2", "Topic-3"], updateListener);

// Example - reading updates
// Assuming the following data is published in Java code from the server:
Payload payload = new JsonPayload("Topic");
payload.addField("Symbol", "GOOG");
payload.addField("Price", "451.13");
server.publish("Topic", payload);

// The data can be retrieved in JavaScript:
function updateListener(sTopic, oData) {
    alert("Symbol: " + oData['Symbol'] + ", Price: " + oData['Price']);
    // Prints "Symbol: GOOG, Price: 451.13"
}

// Example - enumerating all the fields received in an update
function updateListener(sTopic, oData) {
    var allFields = "";
    for (var p in oData) {
        allFields += "oData[" + p + "] = " + oData[p] + "\n";
    }
    alert("Update received: " + allFields);
}

Parameters:

{String|String[]} oTopic

A single topic as a String or multiple topics as a String array to subscribe to

{Function} fListener

A callback function to receive updates on this topic

// Example - unsubscribing from a single topic
hub.unsubscribe("Topic");

// Example - unsubscribing from multiple topics
hub.unsubscribe(["Topic-1", "Topic-2", "Topic-3"]);

Parameters:

{String|String[]} oTopic

A single topic as a String or multiple topics as a String array to unsubscribe from