Prakas Subed

Server is handling fine. In less than 200ms its generating the content and sending out (per avg response time measurement of related servlet/jsp WAS). Browser (IE 6) seems to get confused with multiple AJAX calls made to the server.

The same code works fine on Firefox to update the content within the second without interruption; except there's a noticeable flicker on Firefox when the html rendered with the update.

Originally posted by Eric Pascarello:
Your server is going to come to a crashing halt when it has multiple users. You probably should look at FLEX which is better for real time data.

Eric

To the user it's not excessive. They want to see near real time (minimum of 1 second) update of data on their browser. That's roughly 30KB data that need to be generated and shipped to the browser every second.

However, it's only one page whose final size is less than 32KB when shipped to the browser. Currently this 32Kb HTML replaces an innerHTML on a template html with logos etc already loaded. Users limited to a maximum of 5.

So much for AJAX's simulated push hype?!

With COMET's approach, seems that we will have to redo much of the way things are already done.

Originally posted by Bear Bibeault:
Do you not think that banging on the server every second is a bit excessive? How many pages are doing this sumultaneously?

I have simulated push behavior using AJAX calls from IE. Parts of web page get updated every second getting fresh content from the server using the request object displayed below. However, after a while (some time 5 minutes, sometimes 15 minutes or so later) the update stops happening. The IE icon spins relentlessly, but no content update.

One observation made is that with "netstat -an" on the client system, we can see may be hundred or more connections to server with TCP state "CLOSE_WAIT"

Any suggestions how to get the screen updated without interruption?

if (window.ActiveXObject) { // IE req = new ActiveXObject("Microsoft.XMLHTTP"); if (req) { req.onreadystatechange = processStateChange; try { req.open("GET", url, true); req.send(); } catch (e) { alert("Error while opening URL :" + e); } }

I can get the Y; that's 1000 ms as set on above code. Any pointers on how to get/set X?

Thanks,

AJAX call fails and we receive http code 12002; even when session timeout is set to 0 on web.xml on following code:

We receive the the error inconsistently. i.e. somtimes within 20 minutes of accessing the JSP; sometimes 10 minutes.

We have code similar to following (part of a JSP); appreciate any pointers:


<script> var req; var which; var strContentText; var bottomView = null; function retrieveURL(url) { if (window.XMLHttpRequest) { // Non-IE browsers req = new XMLHttpRequest(); req.onreadystatechange = processStateChange; try { req.open("GET", url, true); } catch (e) { alert(e); } req.send(null); } else if (window.ActiveXObject) { // IE req = new ActiveXObject("Microsoft.XMLHTTP"); if (req) { req.onreadystatechange = processStateChange; req.open("GET", url, true); req.send(); } } } function processStateChange() { if (req.readyState == 4) { // Complete if (req.status == 200) { // OK response var timerId = null; document.getElementById("theTable").innerHTML = req.responseText; timerId = self.setTimeout('retrieveURL(\'\<%= request.getContextPath() %>\/panes\/panesDataBrowse.do\')', 1000); } else { alert("There has been problem getting updated information for this screen: \n" + req.statusText + "Status: " + req.status ); } } }

Has anybody configured openLDAP on WAS 6.0 for a web app. Any experience/how to you can share would be appreciated.

Thanks

To extend this question further...
I wonder if Tomcat/JBoss provide a way to pass actual reason/root cause behind the failure to the login JSP as a param. For our internal/ad hoc system this is desired.

Thanks,

Originally posted by abhijit deshmukh:
hi pradip,

i am still confused about form auth, using j_security_check after succefull login how web server know which is home page i mean which do we hv any thing where we can specify home page.

Thanks & Regards
Abhijeet

Eric,

The way data is outputed to the page is replacing a span with html received from the server:

... if ...req.status == 200... { // OK response var timerId = null; //HOW the data is put the page document.getElementById("theTable").innerHTML = req.responseText; ... <body> <span id="theTable"></span> </body>

Originally posted by Eric Pascarello:
It is not Ajax, it is how the browser is re-renderinig the page.

The question lies in how are you outputting the data to the page? Some general code may help to get to the bottom of the problem.

Eric

I understand your concern; number of users accessing the screen is sized to be less than 3 at any time. We'll have a JBoss server running on Linux (fairly sized; possibly dual processor with plenty of RAM). i.e. we can add more hardware/processing power as necessary. i.e. we'll stand up reasoable server that will live there to serve. Therefore, hit to server is a non-issue for us.

Also, there's no flicker on IE. Flickering on Netscape/Firefox is the issue -- why there's no flicker on IE and yet there's a flicker on Firefox/Netscape? Makes me disappointed to implement AJAX approached solution to find out it doesn't work on Firefox/Netscape.

Originally posted by Eric Pascarello:
You are going to be killing your server with a request a second!!

You are going to get flicker if you have to keep rendering the page over and over.

Eric

Eric,

Thanks for the suggestion. However, the data is expected to change many times within each second. We have been lucky to have a requirement to refresh data only once per second.

Now, does this mean AJAX will not work for near-real time monitoring systems on at least IE and Firefox/Netscape?

Prakas

Originally posted by Eric Pascarello:
I just glanced over that code very quickly. If you keep replacing the content on the page. Mozilla is going to flicker. I personally would do this, cache your request into a variable. Next time the request is made compare the new reult with the one you stored. If they are the same do not process the data. If they differ then process and store this into the cache.

It will save CPU on the user's computer and would get rid of the flicker.

Eric

[ November 16, 2005: Message edited by: Prakas Subed ]

I have a real time moniting page on a browser that gets updated every second using AJAX approach. Code looks as follows:

<a href="http://www.omnytex.com/articles/xhrstruts/" target="_blank" rel="nofollow">http://www.omnytex.com/articles/xhrstruts/</a> [I use the example code to load a URL and feed the page contents from a Strut Action as follows: document.getElementById("theTable").innerHTML = req.responseText; timerId = self.setTimeout('retrieveURL(\'\<%= request.getContextPath() %>\/panes\/panesDataBrowse.do\')', 1000);

Every second update of the screen works pretty neatly on IE; however on Firefox/Netscape the screen flickers. Any idea on things to try to fix this?

Following code is successful in refreshing a page every second without flicker (long live AJAX). However, it makes the browser and JBoss server freeze after a while. Any idea/suggestion on the way AJAX call is implemented?

<pre>

on head script tag var req; var which; function retrieveURL(url) { // alert('retrieveURL' + url + 'Called'); if (window.XMLHttpRequest) { // Non-IE browsers req = new XMLHttpRequest(); req.onreadystatechange = processStateChange; try { req.open("GET", url, true); } catch (e) { alert(e); } req.send(null); } else if (window.ActiveXObject) { // IE req = new ActiveXObject("Microsoft.XMLHTTP"); if (req) { req.onreadystatechange = processStateChange; req.open("GET", url, true); req.send(); } } } function processStateChange() { if (req.readyState == 4) { // Complete if (req.status == 200) { // OK response document.getElementById("theTable").innerHTML = req.responseText; } else { // alert("Problem Text: " + req.statusText + "Status: " + req.status ); } } alert("ok " ); var timerId = self.setTimeout('retrieveURL(\'http:\/\/localhost\:8080\/PRCSWeb\/panes\/panesDataBrowse.do\')', 1000); } [closing script tag] [on head end] <body retrieveURL('http://localhost:8080/PRCSWeb/panes/panesDataBrowse.do');" > <span id="theTable"></span> body end html end

Any one in particular you've liked and the ones you didn't like?

Folks,

at my place we're having too much debate regarding which one to use for a new J2EE web-based app. It'll be typical CRUD application, with lots of validations on data entry/edits. It also has a module that needs to display near real time data using a message queue as the datasource. What to choose; or is combination better? Any reasoning you can provide is appreciated ...

Folks,

I need to collect some pros and cons of these; would you care to mention some please. And which would you chose... Thanks,