[jira] [Commented] (WICKET-5588) Mixing Ajax and Atmosphere updates does not respect order

["Daniel Stoch (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/WICKET-5588?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15081181#comment-15081181 ] 

Daniel Stoch commented on WICKET-5588:
--------------------------------------

The same problem exists when I am using wicket-native-websocket implementation instead of Atmosphere. The similar patch works for me for 6.21.0:
{code}
process: function(data) {
			var context =  {
					attrs: {},
					steps: []
				};
			this._initializeDefaults(context.attrs);
            var res = Wicket.channelManager.schedule(context.attrs.ch, Wicket.bind(function () {
                this.channel = context.attrs.ch;
                var xmlDocument = Wicket.Xml.parse(data);
                this.loadedCallback(xmlDocument, context);
                var executer = new FunctionsExecuter(context.steps);
                executer.start();
                this.done(context.attrs);
            }, this));
            return res !== null ? res: true;
		},
{code}

> Mixing Ajax and Atmosphere updates does not respect order
> ---------------------------------------------------------
>
>                 Key: WICKET-5588
>                 URL: https://issues.apache.org/jira/browse/WICKET-5588
>             Project: Wicket
>          Issue Type: Improvement
>          Components: wicket, wicket-atmosphere
>    Affects Versions: 6.15.0
>            Reporter: Daniel Stoch
>            Assignee: Emond Papegaaij
>
> As far as I know in Wicket ajax calls by default using the same channel and they are queued. But in wicket-atmosphere integration on the client side the refreshing is done by calling (inside wicket-atomosphere.js):
>   Wicket.Ajax.process(response.responseBody);
> It looks like Wicket.Ajax.process() function does not use channels management, so it can result in out-of-order response processing. This method was added to support Atmosphere push calls in Wicket. See the commit (for issue: WICKET-4668):
> https://github.com/apache/wicket/commit/130b063722e55510f2b2a3b47889e14210a5a32f
> *Example scenario to reproduce this problem:*
> When we try to refresh a component (panelA) via ajax when two different threads in the "same" time perform such refresh.
> 1. The first thread (thread1) is a standard servlet container thread to handle user request from a browser:
> - user clicks AjaxLink and on onClick method panelA is refreshed by target.add(panelA).
> 2. The second thread (thread2) is a notification from a backend system which causes a panelA refreshing too:
> - it can be done for eg. using Atmosphere integration by EventBus.post() - panelA is refreshed by target.add(panelA) too.
> On the server side only one thread can access a page at a time so everything is "queued" properly: the thread1 panelA refresh is executed, then the thread2 refresh code is fired.
> But it looks like on the client side the order of ajax calls is undefined: sometimes JS code added from the thread1 is executed as first, sometimes as a second one. On my computer this order almost always is wrong. It leads to an incorrect situation when the component state on a server is different than the DOM tree on the client browser (so for example user can clicks not existing link).



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