Synchronous | Dmytro Shteflyuk's Home https://kpumuk.info In my blog I'll try to describe about interesting technologies, my discovery in IT and some useful things about programming. Mon, 07 Sep 2015 23:56:05 +0000 en-US hourly 1 https://wordpress.org/?v=6.7.1 Synchronous page method call in ASP.NET AJAX library https://kpumuk.info/asp-net/synchronous-page-method-call-in-asp-net-ajax-library/ https://kpumuk.info/asp-net/synchronous-page-method-call-in-asp-net-ajax-library/#comments Mon, 10 Sep 2007 21:15:28 +0000 http://kpumuk.info/asp-net/synchronous-page-method-call-in-asp-net-ajax-library/ Sometimes we need to do some tasks, that libraries developers even have not foreseen. One of such cases is to make synchronous AJAX call (Asynchronous JavaScript And XML). Below you could find quick solution. Please note: my solution is just copy/past of the XmlHttpExecutor code with two small changes: I have passed false as third […]

The post Synchronous page method call in ASP.NET AJAX library first appeared on Dmytro Shteflyuk's Home.]]> Sometimes we need to do some tasks, that libraries developers even have not foreseen. One of such cases is to make synchronous AJAX call (Asynchronous JavaScript And XML). Below you could find quick solution.

Please note: my solution is just copy/past of the XmlHttpExecutor code with two small changes:

  • I have passed false as third parameter of the XMLHttpRequest.open method to make synchronous call.
  • I have cached request results in XMLHttpSyncExecutor members before freeing XMLHttpRequest in the _onReadyStateChange function.

So let’s get started. First of all we would define XMLHttpSyncExecutor class, descendant of the WebRequestExecutor.

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Type.registerNamespace('Sys.Net');

Sys.Net.XMLHttpSyncExecutor = function()
{
    if (arguments.length !== 0) throw Error.parameterCount();
    Sys.Net.XMLHttpSyncExecutor.initializeBase(this);

    var _this = this;
    this._xmlHttpRequest = null;
    this._webRequest = null;
    this._responseAvailable = false;
    this._timedOut = false;
    this._timer = null;
    this._aborted = false;
    this._started = false;

    this._responseData = null;
    this._statusCode = null;
    this._statusText = null;
    this._headers = null;

    this._onReadyStateChange = function () {
        if (_this._xmlHttpRequest.readyState === 4 ) {
            _this._clearTimer();
            _this._responseAvailable = true;

            _this._responseData = _this._xmlHttpRequest.responseText;
            _this._statusCode = _this._xmlHttpRequest.status;
            _this._statusText = _this._xmlHttpRequest.statusText;
            _this._headers = _this._xmlHttpRequest.getAllResponseHeaders();

            _this._webRequest.completed(Sys.EventArgs.Empty);
            if (_this._xmlHttpRequest != null) {
                _this._xmlHttpRequest.onreadystatechange = Function.emptyMethod;
                _this._xmlHttpRequest = null;
            }
        }
    }

    this._clearTimer = function this$_clearTimer() {
        if (_this._timer != null) {
            window.clearTimeout(_this._timer);
            _this._timer = null;
        }
    }

    this._onTimeout = function this$_onTimeout() {
        if (!_this._responseAvailable) {
            _this._clearTimer();
            _this._timedOut = true;
            _this._xmlHttpRequest.onreadystatechange = Function.emptyMethod;
            _this._xmlHttpRequest.abort();
            _this._webRequest.completed(Sys.EventArgs.Empty);
            _this._xmlHttpRequest = null;
        }
    }
}

This is very simple and clean, so I’ll just show you other methods of the XMLHttpSyncExecutor.

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function Sys$Net$XMLHttpSyncExecutor$get_timedOut() {
    /// <value type="Boolean"></value>
    if (arguments.length !== 0) throw Error.parameterCount();
    return this._timedOut;
}

function Sys$Net$XMLHttpSyncExecutor$get_started() {
    /// <value type="Boolean"></value>
    if (arguments.length !== 0) throw Error.parameterCount();
    return this._started;
}

function Sys$Net$XMLHttpSyncExecutor$get_responseAvailable() {
    /// <value type="Boolean"></value>
    if (arguments.length !== 0) throw Error.parameterCount();
    return this._responseAvailable;
}

function Sys$Net$XMLHttpSyncExecutor$get_aborted() {
    /// <value type="Boolean"></value>
    if (arguments.length !== 0) throw Error.parameterCount();
    return this._aborted;
}

function Sys$Net$XMLHttpSyncExecutor$executeRequest() {
    if (arguments.length !== 0) throw Error.parameterCount();
    this._webRequest = this.get_webRequest();

    if (this._started) {
        throw Error.invalidOperation(String.format(Sys.Res.cannotCallOnceStarted, 'executeRequest'));
    }
    if (this._webRequest === null) {
        throw Error.invalidOperation(Sys.Res.nullWebRequest);
    }

    var body = this._webRequest.get_body();
    var headers = this._webRequest.get_headers();
    this._xmlHttpRequest = new XMLHttpRequest();
    this._xmlHttpRequest.onreadystatechange = this._onReadyStateChange;
    var verb = this._webRequest.get_httpVerb();
    this._xmlHttpRequest.open(verb, this._webRequest.getResolvedUrl(), false); // False to call Synchronously
    if (headers) {
        for (var header in headers) {
            var val = headers[header];
            if (typeof(val) !== "function")
                this._xmlHttpRequest.setRequestHeader(header, val);
        }
    }

    if (verb.toLowerCase() === "post") {
        if ((headers === null) || !headers['Content-Type']) {
            this._xmlHttpRequest.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
        }

        if (!body) {
            body = "";
        }
    }

    var timeout = this._webRequest.get_timeout();
    if (timeout > 0) {
        this._timer = window.setTimeout(Function.createDelegate(this, this._onTimeout), timeout);
    }
    this._xmlHttpRequest.send(body);
    this._started = true;
}

 function Sys$Net$XMLHttpSyncExecutor$getAllResponseHeaders() {
    /// <returns type="String"></returns>
    if (arguments.length !== 0) throw Error.parameterCount();
    if (!this._responseAvailable) {
        throw Error.invalidOperation(String.format(Sys.Res.cannotCallBeforeResponse, 'getAllResponseHeaders'));
    }

    return this._headers;
}

function Sys$Net$XMLHttpSyncExecutor$get_responseData() {
    /// <value type="String"></value>
    if (arguments.length !== 0) throw Error.parameterCount();
    if (!this._responseAvailable)
    {
        throw Error.invalidOperation(String.format(Sys.Res.cannotCallBeforeResponse, 'get_responseData'));
    }

    return this._responseData;
}

function Sys$Net$XMLHttpSyncExecutor$get_statusCode() {
    /// <value type="Number"></value>
    if (arguments.length !== 0) throw Error.parameterCount();
    if (!this._responseAvailable)
    {
        throw Error.invalidOperation(String.format(Sys.Res.cannotCallBeforeResponse, 'get_statusCode'));
    }

    return this._statusCode;
}

function Sys$Net$XMLHttpSyncExecutor$get_statusText() {
    /// <value type="String"></value>
    if (arguments.length !== 0) throw Error.parameterCount();
    if (!this._responseAvailable)
    {
        throw Error.invalidOperation(String.format(Sys.Res.cannotCallBeforeResponse, 'get_statusText'));
    }

    return this._statusText;
}

function Sys$Net$XMLHttpSyncExecutor$get_xml() {
    /// <value></value>
    if (arguments.length !== 0) throw Error.parameterCount();
    if (!this._responseAvailable)
    {
        throw Error.invalidOperation(String.format(Sys.Res.cannotCallBeforeResponse, 'get_xml'));
    }

    var xml = this._responseData;
    if ((!xml) || (!xml.documentElement))
    {
        xml = new XMLDOM(this._responseData);
        if ((!xml) || (!xml.documentElement))
        {
            return null;
        }
    }
    else if (navigator.userAgent.indexOf('MSIE') !== -1)
    {
        xml.setProperty('SelectionLanguage', 'XPath');
    }

    if ((xml.documentElement.namespaceURI === "http://www.mozilla.org/newlayout/xml/parsererror.xml") &&
        (xml.documentElement.tagName === "parsererror"))
    {
        return null;
    }

    if (xml.documentElement.firstChild && xml.documentElement.firstChild.tagName === "parsererror")
    {
        return null;
    }

    return xml;
}

function Sys$Net$XMLHttpSyncExecutor$abort() {
    if (arguments.length !== 0) throw Error.parameterCount();
    if (!this._started) {
        throw Error.invalidOperation(Sys.Res.cannotAbortBeforeStart);
    }

    if (this._aborted || this._responseAvailable || this._timedOut)
        return;

    this._aborted = true;

    this._clearTimer();

    if (this._xmlHttpRequest && !this._responseAvailable) {
        this._xmlHttpRequest.onreadystatechange = Function.emptyMethod;
        this._xmlHttpRequest.abort();

        this._xmlHttpRequest = null;
        var handler = this._webRequest._get_eventHandlerList().getHandler("completed");
        if (handler) {
            handler(this, Sys.EventArgs.Empty);
        }
    }
}

Sys.Net.XMLHttpSyncExecutor.prototype = {
    get_timedOut: Sys$Net$XMLHttpSyncExecutor$get_timedOut,
    get_started: Sys$Net$XMLHttpSyncExecutor$get_started,
    get_responseAvailable: Sys$Net$XMLHttpSyncExecutor$get_responseAvailable,
    get_aborted: Sys$Net$XMLHttpSyncExecutor$get_aborted,
    executeRequest: Sys$Net$XMLHttpSyncExecutor$executeRequest,
    getAllResponseHeaders: Sys$Net$XMLHttpSyncExecutor$getAllResponseHeaders,
    get_responseData: Sys$Net$XMLHttpSyncExecutor$get_responseData,
    get_statusCode: Sys$Net$XMLHttpSyncExecutor$get_statusCode,
    get_statusText: Sys$Net$XMLHttpSyncExecutor$get_statusText,
    get_xml: Sys$Net$XMLHttpSyncExecutor$get_xml,
    abort: Sys$Net$XMLHttpSyncExecutor$abort
}
Sys.Net.XMLHttpSyncExecutor.registerClass('Sys.Net.XMLHttpSyncExecutor', Sys.Net.WebRequestExecutor);

And finally we will notify ASP.NET AJAX that script have been loaded.

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if (typeof(Sys) != 'undefined')
{
    Sys.Application.notifyScriptLoaded();
}

Usage is not so simple as wanted, but it’s still quite easy to understand:

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function getServerTime() {
    // Instantiate a WebRequest.
    var wRequest = new Sys.Net.WebRequest();
    // Set the request URL.
    wRequest.set_url(PageMethods.get_path() + "/GetServerTime");
    // Set the request verb.
    wRequest.set_httpVerb('POST');
   
    wRequest.get_headers()['Content-Type'] = 'application/json; charset=utf-8';

    var executor = new Sys.Net.XMLHttpSyncExecutor();
    wRequest.set_executor(executor);
    // Execute the request.
    wRequest.invoke();

    if (executor.get_responseAvailable()) {
        return executor.get_object();
    }
    return false;
}

When you are using ScriptService, you will not see these difficulties, because ASP.NET will generate wrappers by itself. But if you need synchronous AJAX call — sorry, but in this case you should do it manually. Sample solution could be found here.

The post Synchronous page method call in ASP.NET AJAX library first appeared on Dmytro Shteflyuk's Home.]]> https://kpumuk.info/asp-net/synchronous-page-method-call-in-asp-net-ajax-library/feed/ 10