Sorry to add a MyFaces related sidenote to that original RichFaces
announcement post by Kito.
Queue control and timeouts are a huge gap in the JSF 2.0 Ajax specs.
The good side is, one of the reasons why our codebase is bigger than
Mojarras is, we have such a thing in our codebase (as well as partial
page submit) - (another reason is the OO Layer and the faster ll parser
based body and head stripping which outperforms native html/xhtml
browser parsing via iframs and xml parsing, for now)
The main issue is, while we have it in our codebase, you cannot really
expose it to the end users because it is not part of the spec.
you can use it following way:
<script type="text/javascript">
myfaces.queuesize = <fill your number in here>;
</script>
or
if you want to alter it dynamically on the fly
jsf.ajax.request(this, event, {myfaces:{queuesize:<fill in your number
here>}, render="bla", execute:"bla2"}
As I said the reason why this is not exposed is, because it is not part
of the spec and hence I am waiting for the official API after that I can
expose the code.
If we already are at it, we have other features as well, here is an example:
<h:commandButton id = "button1" value = "Increment left" action =
"#{count.increment}" onclick = "jsf.ajax.request(this, event, {render:
'out1', execute: 'out1 button1',
myfaces:{errorlevel:'ERROR', pps:true,
queuesize:1}}); return false;" />
PPS is especially interesting because with it you can issue a partial
page submit, instead of sending down the full form always you can limit
the number of parameters sent (per default afair, the execute chain).
The spec clearly states the entire issuing form must be encoded and sent
down, but with PPS you can limit that which gives an additional extra on
performance. We all got those features thanks to the j4fry ajax code we
integrated which already had it in.
Also an interesting feature is the timeout feature, with it you can
enable timeout control for the ajax part, so that after a given time the
issued Ajax request is dropped and the next one in the chain is processed.
the config parameter is myfaces.timeout, you can apply it like the queue
control.
Werner
Am 29.06.10 01:40, schrieb Kito Mann:
Hello,
This article shows you how to control traffic to the server using the
RichFaces queue. Here is an excerpt:
When building an Ajax application in JSF, one of the things you need to
consider is how to control traffic to the server. Although Ajax
applications make the application richer, quicker, and more interactive,
in many instances the end user is not aware that the client (browser) is
sending Ajax requests to the server. For example, if an input field
fires an Ajax event on the onkeyup event, the user can easily flood the
server with to many requests without even knowing it. This is also true
of a regular button that fires an Ajax request. In a traditional
(non-Ajax) application, the user is more aware that a request was sent.
In such an application, the browser window could go blank for a fraction
of a second while the next page is loaded. In other words, there is
visual clue that page was submitted. But if the button fires an Ajax
request, the page is not reloaded. The user could be clicking the button
every second and not realizing that he or she is firing new requests
each time. If multiple requests are fired almost at the same time, there
is no guarantee they will be processed in the same order without any
additional work on the server.
Read the full article here:
http://www.jsfcentral.com/articles/richfaces_queue.html
Kito D. Mann -- Author, JavaServer Faces in Action
http://twitter.com/kito99 http://twitter.com/jsfcentral
http://www.virtua.com <http://www.virtua.com/> - JSF/Java EE consulting,
training, and mentoring
http://www.JSFCentral.com <http://www.jsfcentral.com/> - JavaServer
Faces FAQ, news, and info
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