a4j:push

[chuaky]

hi any1,

I was considering to use a4j:push for updating a web page. The consideration is to reduce network traffic overhead but still give real time response to user. But the developer guide description for a4j:push says that it "periodically perform Ajax request to server, to simulate 'push' data."

Further reading the guide and tracing the source, it look similar to a a4j:poll but with some improvement in network load, as far as network traffic is concerned. I was a bit surprise on why a4j:push is being implemented in this manner?


My questions are:

Is it possible to implement real server push?

or is there further improvement to a4j:push in future release?

or this method of a4j:push is a good implementation, as compared to ICEFACES?

Hope to gain more insights into this.
Thank you.

[chuaky]

hi every1,

Was looking at the code for a4j:push again, and wondering if it is possible to implement ajax push by long polling. See this website for the meaning:

http://weblogs.java.net/blog/jfarcand/archive/2007/05/new_adventures.html

It may be possible to do long polling by extending the BaseFilter.java, see existing code snippet below:

Sorry, i am not familiar on how to modify functionality to the richfaces sources.

Any advices any1 on how to do this long polling ?
Thanks.

if (request.getAttribute(FILTER_PERFORMED) != Boolean.TRUE) {
 // mark - and not processing same request twice.
 try {
 request.setAttribute(FILTER_PERFORMED, Boolean.TRUE);
 String ajaxPushHeader = httpServletRequest
 .getHeader(AJAX_PUSH_KEY_HEADER);
 // check for a push check request.
 if (httpServletRequest.getMethod().equals("HEAD")
 && null != ajaxPushHeader) {
 PushEventsCounter listener = eventsManager
 .getListener(ajaxPushHeader);
 // To avoid XmlHttpRequest parsing exceptions.
 httpServletResponse.setContentType("text/plain");
 if (listener.isPerformed()) {
 listener.processed();
 httpServletResponse.setStatus(HttpServletResponse.SC_OK);
 httpServletResponse.setHeader(AJAX_PUSH_STATUS_HEADER, AJAX_PUSH_READY);
 if (log.isDebugEnabled()) {
 log.debug("Occurs event for a id " + ajaxPushHeader);
 }
 } else {
 // Response code - 'No content'
 httpServletResponse.setStatus(HttpServletResponse.SC_ACCEPTED);
 if (log.isDebugEnabled()) {
 log.debug("No event for a id " + ajaxPushHeader);
 }

[dragonfly0806]

I am also interested in this topic. Since I am working on a large-scale commercial application, I am worried about the performance of the a4j:push tag. Can anyone speak to load tests or anything like that for this tag? Specifically I would like to see comparisons between a4j:push and the older a4j:poll tag.