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https://issues.apache.org/jira/browse/CB-4873?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14008104#comment-14008104
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Maris Seimanovs edited comment on CB-4873 at 5/24/14 12:34 PM:
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I took the attached project to compare how it behaves on WP8 and WP8.1.
Currently it indeed works fine on WP8, but it fails immediately after executing
the first AJAX call on WP8.1. It throws SystemException on XHRHelper at code
Browser.InvokeScript("__onXHRLocalCallback" (line 297)
And on WP8.1 I also see in Visual Studio Output this line:
{code}
Error calling js to fire nativeReady event. Did you include cordova.js in your
html script tag?
{code}
I suspect, that Microsoft has changed something about event "asynchronity" on
WP8.1.
I'll try to fix the project so it runs on WP8.1.
was (Author: midix):
I took the attached project to compare how it behaves on WP8 and WP8.1.
Currently it indeed works fine on WP8, but it fails immediately after executing
the first AJAX call on WP8.1. It throws SystemException on XHRHelper at code
Browser.InvokeScript("__onXHRLocalCallback" (line 297)
I suspect, that Microsoft has changed something about event "asynchronity" on
WP8.1.
I'll try to fix the project so it runs on WP8.1.
> XHRHelper is failing with simultaneous asynchronous requests
> ------------------------------------------------------------
>
> Key: CB-4873
> URL: https://issues.apache.org/jira/browse/CB-4873
> Project: Apache Cordova
> Issue Type: Bug
> Components: WP7, WP8
> Affects Versions: 3.0.0
> Environment: Any
> Reporter: Jonathan Naguin
> Assignee: Jesse MacFadyen
> Priority: Critical
> Labels: WP8, WP8.1, ajax, asynchronous, multiple, xhrhelper
> Attachments: CordovaWP8_3.6.0-dev1.zip
>
>
> XHRHelper is failing in processing mutiple simultaneous asynchronous AJAX
> requests. I am using the latest code from
> https://github.com/apache/cordova-wp8/blob/master/wp8/template/cordovalib/XHRHelper.cs
> The problem is related with {{_onXHRLocalCallback}} which is save into the
> {{window}} object as a unique function. When, for example, two Ajax requests
> are evaluated at same time, the last {{funk}} function overrides the first
> {{_onXHRLocalCallback}} without receive the data from the C# code to that
> particular request.
> To demostrate this I put {{console.log("XHR: " + resolvedUrl);}} inside
> {{__onXHRLocalCallback}} and
> {{System.Diagnostics.Debug.WriteLine("HandleCommand: " + url);}} in
> {{HandleCommand}} method (my code uses *Require JS* to load this resources).
> The output is this:
> {code}
> HandleCommand: x-wmapp0:www/src/modules/home/HomeView.html
> HandleCommand: x-wmapp0:www/src/modules/orders/OrdersView.html
> XHR: x-wmapp0:www/src/modules/orders/OrdersView.html
> XHR: x-wmapp0:www/src/modules/orders/OrdersView.html
> XHR: HandleCommand: x-wmapp0:www/src/modules/order/OrderDetailView.html
> XHR: x-wmapp0:www/src/modules/order/OrderDetailView.html
> {code}
> As you can see, one request is missing: "HomeView.html".
> h6. NOTES
> - If I set {{false}} the {{this.isAsync}} variable it works (this way it is
> executed without using setTimeout).
> - If I put a console.log before launch {{funk}} it works.
> - It works on the simulator, but it fails on a real device.
> h6. Possible solution
> In conclusion, I assumed that it's a timing problem. To resolve it I decided
> to save a onXHRLocalCallback function per each request:
> {code}
> var funk = function () {
> if (! window.__onXHRLocalCallback){
> window.__onXHRLocalCallback = {}; //Object to store the functions
> }
>
> window.__onXHRLocalCallback[resolvedUrl] = function (responseCode,
> responseText) {
> alias.status = responseCode;
> if (responseCode == '200') {
> alias.responseText = responseText;
> }
> else {
> alias.onerror && alias.onerror(responseCode);
> }
> alias.changeReadyState(XHRShim.DONE);
> delete window.__onXHRLocalCallback[resolvedUrl]; //Delete the function
> }
> alias.changeReadyState(XHRShim.LOADING);
> window.external.Notify('XHRLOCAL/' + resolvedUrl);
> }
> {code}
> So I had to change in {{HandleCommand}} method the way of invoking this
> callback. I decided to create a helper function to be called in each case:
> {code}
> /// <summary>
> /// Invoke a XHR callback
> /// </summary>
> /// <param name="url">The URL of the request</param>
> /// <param name="code">The response code</param>
> /// <param name="text">The response text</param>
> private void InvokeCallback(string url, int code, string text)
> {
> string args = string.Format("('{0}', {1}, {2});", code,
> WPCordovaClassLib.Cordova.JSON.JsonHelper.Serialize(text),
> WPCordovaClassLib.Cordova.JSON.JsonHelper.Serialize(url));
> string callback = @"(function(code, text, url){
> try {
> window.__onXHRLocalCallback[ url ].call(null, code, text);
> }
> catch(e) {
> console.log('Error calling method from XHRHelper :: ' + e);
> }
> })" + args;
> Browser.InvokeScript("eval", new string[] { callback });
> }
> {code}
> To be called as {{InvokeCallback(url, 200, text);}} or {{InvokeCallback(url,
> 404, null);}}
> Thanks.
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