AbstractAjaxTimerBehavior showing different issues on several browsers when
used for polling data and updating browser's DOM
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Key: WICKET-2246
URL: https://issues.apache.org/jira/browse/WICKET-2246
Project: Wicket
Issue Type: Bug
Components: wicket
Affects Versions: 1.4-RC2
Environment:
This issue affects several browsers. These browsers and versions have been used
for testing:
* Mozilla Firefox 3.0.9 (Windows XP) and 3.0.1 (Linux)
* Internet Explorer 7.0.5730.13 (Windows XP)
* Opera 9.64 (Windows XP and Linux)
* Google Chrome 1.0.154.59 (Windows XP)
The web application is deployed on an Apache Tomcat 5.5.27 server.
Reporter: Daniel Fernández
Scenario
=========
A page contains a dashboard, which is a table with several rows of data, in
which each row must retrieve its data from a different business process. All of
these rows' processes are very heavy, and they all should be executed
concurrently when the dashboard is loaded. Each row should show its data as
soon as it is available, not waiting for other rows to finish and disregarding
their order or position inside the table.
Being the busines processes heavy, they will be executed asynchronously, and
each row will perform scheduled AJAX polling operations against the server by
using a subclass of AbstracAjaxTimerBehavior. While the data computation is not
complete, a typical rotating indicator image will be shown, which will be
substituted by the data when it is available.
This scenario and the issues that arise can be simulated with the files
contained in the attached file, which have comments explaining their function.
1st issue: OPERA does not update DOM correctly
==============================================
When using Opera to browse this page, after some time the "Wicket AJAX Debug"
window will show that all the data for all the rows have already been sent to
the browser, but Opera may not have updated the DOM for all these rows
correctly, and so only some rows may be showing their data.
This effect occurs in a quite random manner (it even works completely alright
sometimes), and it gets worse with network latency (it is worse when tested on
a remote server than it is in localhost).
2nd issue: FIREFOX, IE and CHROME stop polling the server after a fresh start
=============================================================================
When using these three browsers, it may happen that the browser suddenly stops
sending AJAX requests for row data (or even does not send it at all for some
rows), and so obviously it never gets loaded.
This only happens after a fresh start of the browser, and everything works
perfectly fine after hitting the "reload" button. It also occurs in a quite
random manner and works completely alright sometimes, but it gets much worse
with network latency (worse when tested on a remote server, as happens with
issue no.1).
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