bootstrap.js

/*
 * Bootstrapping code.
 */
var Dingo;
Dingo = (function () {
    var encoders = {};
    var decoders = {};

    function getWidget(i) {
        return $('#i' + i);
    }

    function encodeAll(encoders) {
        var encodedState = {};
        $.each(encoders, function(widgetId, encoder) {
            var widget;
            widget = getWidget(widgetId);
            if (widget.length > 0) {
		if (typeof encoder === 'function') {
		    encodedState[widgetId] = encoder.call(widget);
		}
            }
        } );
        return encodedState;
    }
    
    function addEncoder(id, encoderFunc) {
        if (encoderFunc !== null) {
	    encoders[id] = encoderFunc;
        }
    }

    function addDecoder(id, decoderFunc) {
        if (decoderFunc !== null) {
            decoders[id] = decoderFunc;
        }
    }

    function setWidgetValue(id, json) {
        var d = decoders[id];
        if (typeof d === 'function') {
            d.call(getWidget(id), json);
        }
    }

    // Long polling handler.
    function poll() {
        var delay = 0;
        // Otherwise we start one...
        console.log("Starting long polling...");
        $.ajax({
            error : function (xhr, status, err) {
                if (err === 'timeout') {
                    delay = 0; // timeout means we need to retry immediately
                } else {
                    delay = 15000; // don't hammer the server
                }
            },
            success : function (data, status, xhr) {
                // Start polling immediately again.
                delay = 0;
            },
            complete : function () {
                // Restart poll.
                setTimeout(poll, delay);
            },
            timeout : 60000,
            data : { },
            type : 'GET',
            dataType : 'script',
            url: '/poll'
        });
    }

    // Set up the callback handler.
    function callback(id) {
        var encodedState;
        // Go.
	encodedState = encodeAll(encoders);
	console.log("Performing callback", id);
	console.log("Callback data: ", encodedState);
	$.ajax({ 
	    error : function (xhr, status, err) {
		console.log("Callback", id, " error ", err);
		// FIXME: Handle errors appropriately.
	    },
	    success : function (data, status, xhr) {
		console.log("Callback completed", data, status);
	    },
            complete : function () {
                // Start polling once the initial callback has been processed.
                if (id === 0) {
                    poll(); 
                }
            },
	    data : { 'state' : JSON.stringify(encodedState) },
            type : 'POST',
	    dataType : 'script',
	    url: '/callback/' + id
	});
    }
    // Return the methods.
    return { 'callback' : callback,
	     'addEncoder' : addEncoder,
             'addDecoder' : addDecoder,
             'setWidgetValue' : setWidgetValue
	   };
}());

/*
 * Bootstrap.
 */
$(document).ready(function () {
    // Start by invoking the bootstrap callback.
    Dingo.callback(0);
});