dklab_realplexor.js

// Constructor.
// Create new Dklab_Realplexor object.
function Dklab_Realplexor(fullUrl, namespace, viaDocumentWrite)
{
    // Current JS library version.
    var VERSION = "1.32";

    // Detect current page hostname.
    var host = document.location.host;

    // Assign initial properties.
    if (!this.constructor._registry) this.constructor._registry = {}; // all objects registry
    this.version = VERSION;
    this._map = {};
    this._realplexor = null;
    this._namespace = namespace;
    this._login = null;
    this._iframeId = "mpl" + (new Date().getTime());
    this._iframeTag =
        '<iframe'
        + ' id="' + this._iframeId + '"'
        + ' onload="' + 'Dklab_Realplexor' + '._iframeLoaded(&quot;' + this._iframeId + '&quot;)"'
        + ' src="' + fullUrl + '?identifier=IFRAME&amp;HOST=' + host + '&amp;version=' + this.version + '"'
        + ' style="position:absolute; visibility:hidden; width:200px; height:200px; left:-1000px; top:-1000px"' +
        '></iframe>';
    this._iframeCreated = false;
    this._needExecute = false;
    this._executeTimer = null;

    // Register this object in the registry (for IFRAME onload callback).
    this.constructor._registry[this._iframeId] = this;

    // Validate realplexor URL.
    if (!fullUrl.match(/^\w+:\/\/([^/]+)/)) {
        throw 'Dklab_Realplexor constructor argument must be fully-qualified URL, ' + fullUrl + ' given.';
    }
    var mHost = RegExp.$1;
    if (mHost != host && mHost.lastIndexOf("." + host) != mHost.length - host.length - 1) {
        throw 'Due to the standard XMLHttpRequest security policy, hostname in URL passed to Dklab_Realplexor (' + mHost + ') must be equals to the current host (' + host + ') or be its direct sub-domain.';
    }

    // Create IFRAME if requested.
    if (viaDocumentWrite) {
        document.write(this._iframeTag);
        this._iframeCreated = true;
    }

    // Allow realplexor's IFRAME to access outer window.
    document.domain = host;
}

// Static function.
// Called when a realplexor iframe is loaded.
Dklab_Realplexor._iframeLoaded = function(id)
{
    var th = this._registry[id];
    // use setTimeout to let IFRAME JavaScript code some time to execute.
    setTimeout(function() {
        var iframe = document.getElementById(id);
        th._realplexor = iframe.contentWindow.Dklab_Realplexor_Loader;
        if (th.needExecute) {
            th.execute();
        }
    }, 50);
}

// Set active login.
Dklab_Realplexor.prototype.logon = function(login) {
    this._login = login;
}

// Set the position from which we need to listen a specified ID.
Dklab_Realplexor.prototype.setCursor = function(id, cursor) {
    if (!this._map[id]) this._map[id] = { cursor: null, callbacks: [] };
    this._map[id].cursor = cursor;
    return this;
}

// Subscribe a new callback to specified ID.
// To apply changes and reconnect to the server, call execute()
// after a sequence of subscribe() calls.
Dklab_Realplexor.prototype.subscribe = function(id, callback) {
    if (!this._map[id]) this._map[id] = { cursor: null, callbacks: [] };
    var chain = this._map[id].callbacks;
    for (var i = 0; i < chain.length; i++) {
        if (chain[i] === callback) return this;
    }
    chain.push(callback);
    return this;
}

// Unsubscribe a callback from the specified ID.
// You do not need to reconnect to the server (see execute())
// to stop calling of this callback.
Dklab_Realplexor.prototype.unsubscribe = function(id, callback) {
    if (!this._map[id]) return this;
    if (callback == null) {
        this._map[id].callbacks = [];
        return this;
    }
    var chain = this._map[id].callbacks;
    for (var i = 0; i < chain.length; i++) {
        if (chain[i] === callback) {
            chain.splice(i, 1);
            return this;
        }
    }
    return this;
}

// Reconnect to the server and listen for all specified IDs.
// You should call this method after a number of calls to subscribe().
Dklab_Realplexor.prototype.execute = function() {
    // Control IFRAME creation.
    if (!this._iframeCreated) {
        var div = document.createElement('DIV');
        div.innerHTML = this._iframeTag;
        document.body.appendChild(div);
        this._iframeCreated = true;
    }

    // Check if the realplexor is ready (if not, schedule later execution).
    if (this._executeTimer) {
        clearTimeout(this._executeTimer);
        this._executeTimer = null;
    }
    var th = this;
    if (!this._realplexor) {
        this._executeTimer = setTimeout(function() { th.execute() }, 30);
        return;
    }

    // Realplexor loader is ready, run it.
    this._realplexor.execute(
        this._map,
        this.constructor._callAndReturnException,
        (this._login != null? this._login + "_" : "") + (this._namespace != null? this._namespace : "")
    );
}

// This is a work-around for stupid IE. Unfortunately IE cannot
// catch exceptions which are thrown from the different frame
// (in most cases). Please see
// http://blogs.msdn.com/jaiprakash/archive/2007/01/22/jscript-exceptions-not-handled-thrown-across-frames-if-thrown-from-a-expando-method.aspx
Dklab_Realplexor._callAndReturnException = function(func, args) {
    try {
        func.apply(null, args);
        return null;
    } catch (e) {
        return "" + e;
    }
}