jquery.signalR.transports.common.js

// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.

/*global window:false */
/// <reference path="jquery.signalR.core.js" />

(function ($, window, undefined) {
    "use strict";

    var signalR = $.signalR,
        events = $.signalR.events,
        changeState = $.signalR.changeState,
        startAbortText = "__Start Aborted__",
        transportLogic;

    signalR.transports = {};

    function beat(connection) {
        if (connection._.keepAliveData.monitoring) {
            checkIfAlive(connection);
        }

        // Ensure that we successfully marked active before continuing the heartbeat.
        if (transportLogic.markActive(connection)) {
            connection._.beatHandle = window.setTimeout(function () {
                beat(connection);
            }, connection._.beatInterval);
        }
    }

    function checkIfAlive(connection) {
        var keepAliveData = connection._.keepAliveData,
            timeElapsed;

        // Only check if we're connected
        if (connection.state === signalR.connectionState.connected) {
            timeElapsed = new Date().getTime() - connection._.lastMessageAt;

            // Check if the keep alive has completely timed out
            if (timeElapsed >= keepAliveData.timeout) {
                connection.log("Keep alive timed out.  Notifying transport that connection has been lost.");

                // Notify transport that the connection has been lost
                connection.transport.lostConnection(connection);
            } else if (timeElapsed >= keepAliveData.timeoutWarning) {
                // This is to assure that the user only gets a single warning
                if (!keepAliveData.userNotified) {
                    connection.log("Keep alive has been missed, connection may be dead/slow.");
                    $(connection).triggerHandler(events.onConnectionSlow);
                    keepAliveData.userNotified = true;
                }
            } else {
                keepAliveData.userNotified = false;
            }
        }
    }

    function getAjaxUrl(connection, path) {
        var url = connection.url + path;

        if (connection.transport) {
            url += "?transport=" + connection.transport.name;
        }

        return transportLogic.prepareQueryString(connection, url);
    }

    function InitHandler(connection) {
        this.connection = connection;

        this.startRequested = false;
        this.startCompleted = false;
        this.connectionStopped = false;
    }

    InitHandler.prototype = {
        start: function (transport, onSuccess, onFallback) {
            var that = this,
                connection = that.connection,
                failCalled = false;

            if (that.startRequested || that.connectionStopped) {
                connection.log("WARNING! " + transport.name + " transport cannot be started. Initialization ongoing or completed.");
                return;
            }

            connection.log(transport.name + " transport starting.");

            transport.start(connection, function () {
                if (!failCalled) {
                    that.initReceived(transport, onSuccess);
                }
            }, function (error) {
                // Don't allow the same transport to cause onFallback to be called twice
                if (!failCalled) {
                    failCalled = true;
                    that.transportFailed(transport, error, onFallback);
                }

                // Returns true if the transport should stop;
                // false if it should attempt to reconnect
                return !that.startCompleted || that.connectionStopped;
            });

            that.transportTimeoutHandle = window.setTimeout(function () {
                if (!failCalled) {
                    failCalled = true;
                    connection.log(transport.name + " transport timed out when trying to connect.");
                    that.transportFailed(transport, undefined, onFallback);
                }
            }, connection._.totalTransportConnectTimeout);
        },

        stop: function () {
            this.connectionStopped = true;
            window.clearTimeout(this.transportTimeoutHandle);
            signalR.transports._logic.tryAbortStartRequest(this.connection);
        },

        initReceived: function (transport, onSuccess) {
            var that = this,
                connection = that.connection;

            if (that.startRequested) {
                connection.log("WARNING! The client received multiple init messages.");
                return;
            }

            if (that.connectionStopped) {
                return;
            }

            that.startRequested = true;
            window.clearTimeout(that.transportTimeoutHandle);

            connection.log(transport.name + " transport connected. Initiating start request.");
            signalR.transports._logic.ajaxStart(connection, function () {
                that.startCompleted = true;
                onSuccess();
            });
        },

        transportFailed: function (transport, error, onFallback) {
            var connection = this.connection,
                deferred = connection._deferral,
                wrappedError;

            if (this.connectionStopped) {
                return;
            }

            window.clearTimeout(this.transportTimeoutHandle);

            if (!this.startRequested) {
                transport.stop(connection);

                connection.log(transport.name + " transport failed to connect. Attempting to fall back.");
                onFallback();
            } else if (!this.startCompleted) {
                // Do not attempt to fall back if a start request is ongoing during a transport failure.
                // Instead, trigger an error and stop the connection.
                wrappedError = signalR._.error(signalR.resources.errorDuringStartRequest, error);

                connection.log(transport.name + " transport failed during the start request. Stopping the connection.");
                $(connection).triggerHandler(events.onError, [wrappedError]);
                if (deferred) {
                    deferred.reject(wrappedError);
                }

                connection.stop();
            } else {
                // The start request has completed, but the connection has not stopped.
                // No need to do anything here. The transport should attempt its normal reconnect logic.
            }
        }
    };

    transportLogic = signalR.transports._logic = {
        ajax: function (connection, options) {
            return $.ajax(
                $.extend(/*deep copy*/ true, {}, $.signalR.ajaxDefaults, {
                    type: "GET",
                    data: {},
                    xhrFields: { withCredentials: connection.withCredentials },
                    contentType: connection.contentType,
                    dataType: connection.ajaxDataType
                }, options));
        },

        pingServer: function (connection) {
            /// <summary>Pings the server</summary>
            /// <param name="connection" type="signalr">Connection associated with the server ping</param>
            /// <returns type="signalR" />
            var url,
                xhr,
                deferral = $.Deferred();

            if (connection.transport) {
                url = connection.url + "/ping";

                url = transportLogic.addQs(url, connection.qs);

                xhr = transportLogic.ajax(connection, {
                    url: url,
                    success: function (result) {
                        var data;

                        try {
                            data = connection._parseResponse(result);
                        }
                        catch (error) {
                            deferral.reject(
                                signalR._.transportError(
                                    signalR.resources.pingServerFailedParse,
                                    connection.transport,
                                    error,
                                    xhr
                                )
                            );
                            connection.stop();
                            return;
                        }

                        if (data.Response === "pong") {
                            deferral.resolve();
                        }
                        else {
                            deferral.reject(
                                signalR._.transportError(
                                    signalR._.format(signalR.resources.pingServerFailedInvalidResponse, result),
                                    connection.transport,
                                    null /* error */,
                                    xhr
                                )
                            );
                        }
                    },
                    error: function (error) {
                        if (error.status === 401 || error.status === 403) {
                            deferral.reject(
                                signalR._.transportError(
                                    signalR._.format(signalR.resources.pingServerFailedStatusCode, error.status),
                                    connection.transport,
                                    error,
                                    xhr
                                )
                            );
                            connection.stop();
                        }
                        else {
                            deferral.reject(
                                signalR._.transportError(
                                    signalR.resources.pingServerFailed,
                                    connection.transport,
                                    error,
                                    xhr
                                )
                            );
                        }
                    }
                });
            }
            else {
                deferral.reject(
                    signalR._.transportError(
                        signalR.resources.noConnectionTransport,
                        connection.transport
                    )
                );
            }

            return deferral.promise();
        },

        prepareQueryString: function (connection, url) {
            var preparedUrl;

            // Use addQs to start since it handles the ?/& prefix for us
            preparedUrl = transportLogic.addQs(url, "clientProtocol=" + connection.clientProtocol);

            // Add the user-specified query string params if any
            preparedUrl = transportLogic.addQs(preparedUrl, connection.qs);

            if (connection.token) {
                preparedUrl += "&connectionToken=" + window.encodeURIComponent(connection.token);
            }

            if (connection.data) {
                preparedUrl += "&connectionData=" + window.encodeURIComponent(connection.data);
            }

            return preparedUrl;
        },

        addQs: function (url, qs) {
            var appender = url.indexOf("?") !== -1 ? "&" : "?",
                firstChar;

            if (!qs) {
                return url;
            }

            if (typeof (qs) === "object") {
                return url + appender + $.param(qs);
            }

            if (typeof (qs) === "string") {
                firstChar = qs.charAt(0);

                if (firstChar === "?" || firstChar === "&") {
                    appender = "";
                }

                return url + appender + qs;
            }

            throw new Error("Query string property must be either a string or object.");
        },

        // BUG #2953: The url needs to be same otherwise it will cause a memory leak
        getUrl: function (connection, transport, reconnecting, poll, ajaxPost) {
            /// <summary>Gets the url for making a GET based connect request</summary>
            var baseUrl = transport === "webSockets" ? "" : connection.baseUrl,
                url = baseUrl + connection.appRelativeUrl,
                qs = "transport=" + transport;

            if (!ajaxPost && connection.groupsToken) {
                qs += "&groupsToken=" + window.encodeURIComponent(connection.groupsToken);
            }

            if (!reconnecting) {
                url += "/connect";
            } else {
                if (poll) {
                    // longPolling transport specific
                    url += "/poll";
                } else {
                    url += "/reconnect";
                }

                if (!ajaxPost && connection.messageId) {
                    qs += "&messageId=" + window.encodeURIComponent(connection.messageId);
                }
            }
            url += "?" + qs;
            url = transportLogic.prepareQueryString(connection, url);

            if (!ajaxPost) {
                url += "&tid=" + Math.floor(Math.random() * 11);
            }

            return url;
        },

        maximizePersistentResponse: function (minPersistentResponse) {
            return {
                MessageId: minPersistentResponse.C,
                Messages: minPersistentResponse.M,
                Initialized: typeof (minPersistentResponse.S) !== "undefined" ? true : false,
                ShouldReconnect: typeof (minPersistentResponse.T) !== "undefined" ? true : false,
                LongPollDelay: minPersistentResponse.L,
                GroupsToken: minPersistentResponse.G
            };
        },

        updateGroups: function (connection, groupsToken) {
            if (groupsToken) {
                connection.groupsToken = groupsToken;
            }
        },

        stringifySend: function (connection, message) {
            if (typeof (message) === "string" || typeof (message) === "undefined" || message === null) {
                return message;
            }
            return connection.json.stringify(message);
        },

        ajaxSend: function (connection, data) {
            var payload = transportLogic.stringifySend(connection, data),
                url = getAjaxUrl(connection, "/send"),
                xhr,
                onFail = function (error, connection) {
                    $(connection).triggerHandler(events.onError, [signalR._.transportError(signalR.resources.sendFailed, connection.transport, error, xhr), data]);
                };


            xhr = transportLogic.ajax(connection, {
                url: url,
                type: connection.ajaxDataType === "jsonp" ? "GET" : "POST",
                contentType: signalR._.defaultContentType,
                data: {
                    data: payload
                },
                success: function (result) {
                    var res;

                    if (result) {
                        try {
                            res = connection._parseResponse(result);
                        }
                        catch (error) {
                            onFail(error, connection);
                            connection.stop();
                            return;
                        }

                        transportLogic.triggerReceived(connection, res);
                    }
                },
                error: function (error, textStatus) {
                    if (textStatus === "abort" || textStatus === "parsererror") {
                        // The parsererror happens for sends that don't return any data, and hence
                        // don't write the jsonp callback to the response. This is harder to fix on the server
                        // so just hack around it on the client for now.
                        return;
                    }

                    onFail(error, connection);
                }
            });

            return xhr;
        },

        ajaxAbort: function (connection, async) {
            if (typeof (connection.transport) === "undefined") {
                return;
            }

            // Async by default unless explicitly overidden
            async = typeof async === "undefined" ? true : async;

            var url = getAjaxUrl(connection, "/abort");

            transportLogic.ajax(connection, {
                url: url,
                async: async,
                timeout: 1000,
                type: "POST"
            });

            connection.log("Fired ajax abort async = " + async + ".");
        },

        ajaxStart: function (connection, onSuccess) {
            var rejectDeferred = function (error) {
                    var deferred = connection._deferral;
                    if (deferred) {
                        deferred.reject(error);
                    }
                },
                triggerStartError = function (error) {
                    connection.log("The start request failed. Stopping the connection.");
                    $(connection).triggerHandler(events.onError, [error]);
                    rejectDeferred(error);
                    connection.stop();
                };

            connection._.startRequest = transportLogic.ajax(connection, {
                url: getAjaxUrl(connection, "/start"),
                success: function (result, statusText, xhr) {
                    var data;

                    try {
                        data = connection._parseResponse(result);
                    } catch (error) {
                        triggerStartError(signalR._.error(
                            signalR._.format(signalR.resources.errorParsingStartResponse, result),
                            error, xhr));
                        return;
                    }

                    if (data.Response === "started") {
                        onSuccess();
                    } else {
                        triggerStartError(signalR._.error(
                            signalR._.format(signalR.resources.invalidStartResponse, result),
                            null /* error */, xhr));
                    }
                },
                error: function (xhr, statusText, error) {
                    if (statusText !== startAbortText) {
                        triggerStartError(signalR._.error(
                            signalR.resources.errorDuringStartRequest,
                            error, xhr));
                    } else {
                        // Stop has been called, no need to trigger the error handler
                        // or stop the connection again with onStartError
                        connection.log("The start request aborted because connection.stop() was called.");
                        rejectDeferred(signalR._.error(
                            signalR.resources.stoppedDuringStartRequest,
                            null /* error */, xhr));
                    }
                }
            });
        },

        tryAbortStartRequest: function (connection) {
            if (connection._.startRequest) {
                // If the start request has already completed this will noop.
                connection._.startRequest.abort(startAbortText);
                delete connection._.startRequest;
            }
        },

        tryInitialize: function (connection, persistentResponse, onInitialized) {
            if (persistentResponse.Initialized && onInitialized) {
                onInitialized();
            } else if (persistentResponse.Initialized) {
                connection.log("WARNING! The client received an init message after reconnecting.");
            }

        },

        triggerReceived: function (connection, data) {
            if (!connection._.connectingMessageBuffer.tryBuffer(data)) {
                $(connection).triggerHandler(events.onReceived, [data]);
            }
        },

        processMessages: function (connection, minData, onInitialized) {
            var data;

            // Update the last message time stamp
            transportLogic.markLastMessage(connection);

            if (minData) {
                data = transportLogic.maximizePersistentResponse(minData);

                transportLogic.updateGroups(connection, data.GroupsToken);

                if (data.MessageId) {
                    connection.messageId = data.MessageId;
                }

                if (data.Messages) {
                    $.each(data.Messages, function (index, message) {
                        transportLogic.triggerReceived(connection, message);
                    });

                    transportLogic.tryInitialize(connection, data, onInitialized);
                }
            }
        },

        monitorKeepAlive: function (connection) {
            var keepAliveData = connection._.keepAliveData;

            // If we haven't initiated the keep alive timeouts then we need to
            if (!keepAliveData.monitoring) {
                keepAliveData.monitoring = true;

                transportLogic.markLastMessage(connection);

                // Save the function so we can unbind it on stop
                connection._.keepAliveData.reconnectKeepAliveUpdate = function () {
                    // Mark a new message so that keep alive doesn't time out connections
                    transportLogic.markLastMessage(connection);
                };

                // Update Keep alive on reconnect
                $(connection).bind(events.onReconnect, connection._.keepAliveData.reconnectKeepAliveUpdate);

                connection.log("Now monitoring keep alive with a warning timeout of " + keepAliveData.timeoutWarning + ", keep alive timeout of " + keepAliveData.timeout + " and disconnecting timeout of " + connection.disconnectTimeout);
            } else {
                connection.log("Tried to monitor keep alive but it's already being monitored.");
            }
        },

        stopMonitoringKeepAlive: function (connection) {
            var keepAliveData = connection._.keepAliveData;

            // Only attempt to stop the keep alive monitoring if its being monitored
            if (keepAliveData.monitoring) {
                // Stop monitoring
                keepAliveData.monitoring = false;

                // Remove the updateKeepAlive function from the reconnect event
                $(connection).unbind(events.onReconnect, connection._.keepAliveData.reconnectKeepAliveUpdate);

                // Clear all the keep alive data
                connection._.keepAliveData = {};
                connection.log("Stopping the monitoring of the keep alive.");
            }
        },

        startHeartbeat: function (connection) {
            connection._.lastActiveAt = new Date().getTime();
            beat(connection);
        },

        markLastMessage: function (connection) {
            connection._.lastMessageAt = new Date().getTime();
        },

        markActive: function (connection) {
            if (transportLogic.verifyLastActive(connection)) {
                connection._.lastActiveAt = new Date().getTime();
                return true;
            }

            return false;
        },

        isConnectedOrReconnecting: function (connection) {
            return connection.state === signalR.connectionState.connected ||
                   connection.state === signalR.connectionState.reconnecting;
        },

        ensureReconnectingState: function (connection) {
            if (changeState(connection,
                        signalR.connectionState.connected,
                        signalR.connectionState.reconnecting) === true) {
                $(connection).triggerHandler(events.onReconnecting);
            }
            return connection.state === signalR.connectionState.reconnecting;
        },

        clearReconnectTimeout: function (connection) {
            if (connection && connection._.reconnectTimeout) {
                window.clearTimeout(connection._.reconnectTimeout);
                delete connection._.reconnectTimeout;
            }
        },

        verifyLastActive: function (connection) {
            if (new Date().getTime() - connection._.lastActiveAt >= connection.reconnectWindow) {
                var message = signalR._.format(signalR.resources.reconnectWindowTimeout, new Date(connection._.lastActiveAt), connection.reconnectWindow);
                connection.log(message);
                $(connection).triggerHandler(events.onError, [signalR._.error(message, /* source */ "TimeoutException")]);
                connection.stop(/* async */ false, /* notifyServer */ false);
                return false;
            }

            return true;
        },

        reconnect: function (connection, transportName) {
            var transport = signalR.transports[transportName];

            // We should only set a reconnectTimeout if we are currently connected
            // and a reconnectTimeout isn't already set.
            if (transportLogic.isConnectedOrReconnecting(connection) && !connection._.reconnectTimeout) {
                // Need to verify before the setTimeout occurs because an application sleep could occur during the setTimeout duration.
                if (!transportLogic.verifyLastActive(connection)) {
                    return;
                }

                connection._.reconnectTimeout = window.setTimeout(function () {
                    if (!transportLogic.verifyLastActive(connection)) {
                        return;
                    }

                    transport.stop(connection);

                    if (transportLogic.ensureReconnectingState(connection)) {
                        connection.log(transportName + " reconnecting.");
                        transport.start(connection);
                    }
                }, connection.reconnectDelay);
            }
        },

        handleParseFailure: function (connection, result, error, onFailed, context) {
            var wrappedError = signalR._.transportError(
                signalR._.format(signalR.resources.parseFailed, result),
                connection.transport,
                error,
                context);

            // If we're in the initialization phase trigger onFailed, otherwise stop the connection.
            if (onFailed && onFailed(wrappedError)) {
                connection.log("Failed to parse server response while attempting to connect.");
            } else {
                $(connection).triggerHandler(events.onError, [wrappedError]);
                connection.stop();
            }
        },

        initHandler: function (connection) {
            return new InitHandler(connection);
        },

        foreverFrame: {
            count: 0,
            connections: {}
        }
    };

}(window.jQuery, window));