Web Push Technology

[souravm <SO...@infosys.com>]

Hi All,

Though it is not directly related to Struts but thought of getting
valueable valuable inputs from the Web guru's in this forum.

This is regarding use of push technology for sending alert messages from
a server to user's browsers.

The push will need to be initiated by an alert server or streaming
engine, which will keep pushing data (alerts) to the users's browsers.
Now the key thing is not just the instant alert but the use of streaming
engine as a central repository for publishing all types of messages from
all type of applications.

In that context I'll like to know

1. The pros and cons -
I can see some pros and cons for it -
- If you use push, you need to have persistent connection with the
browsers, throwing the scalability out of orbit (considering our
requirement of 30,000 logged in users to start with)
- If some kind of pull with auto refresh is used with frequency set at a
very low interval, it will create a lot of http traffic

2. What are the relevant technologies avaialble in Java/J2EE for this -
a) How AJAX an be used ?
b) I was going through pushlet (www.pushlet.com) concept in one site.
But still not sure how reliable that concept.

In overall, looking for thought points on the high level philosophy
(whether it is at all recommended) and also the implementation option of
the same in Java/J2EE.

Any input/pointer would be really helpful.

Regards,
Sourav


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Re: Web Push Technology

[Michael Jouravlev <jm...@gmail.com>]

On 1/3/06, Rick Reumann <st...@reumann.net> wrote:
> > 2. What are the relevant technologies avaialble in Java/J2EE for this -
> > a) How AJAX an be used ?
>
> I'd use the buzz word Ajax for that. I only know the very basics of it

How an async HTTP request can be a push technology?

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Re: Web Push Technology

["Frank W. Zammetti" <fz...@omnytex.com>]

Indeed, Rick is correct, this is not really technically feasible given the
basic nature of HTTP.  Any solution would have to be of pull nature,
unless you get into applets of ActiveX or such things.  You essentially
need to have a server running on the client... then the "real" server
could, theoretically, get the IP of the client and "push" requests out to
it.  But, with nothing to receive it, which is the basic nature of HTTP,
your sunk.

You can of course do a timed pull type thing, which is pretty typical. 
For this, AJAX is pretty ideal, assuming you are OK with requiring
scripting.  If you go that route, I suggest look at AjaxTags in Java Web
Parts:

http://javawebparts.sourceforge.net

Take a look at the Javadocs for the taglib package... I recently added a
<ajax:timer> tag that allows you to set up timed AJAX events that will
fire at a defined interval while still allowing you to use all the
handlers AjaxTags comes with.  With this you should be able to do what you
want with very little effort on your part (aside from what happens on the
server of course, which AjaxTags says nothing about).

Whether you use this or not, your talking about a polling solution most
likely.  But, if the polling interval is fast enough (but not too fast
lest you crush your server!), it should work pretty well.  Usually, alerts
can tolerate some degree of delay, so if you set the interval to 10
seconds or some such, it should be OK.

-- 
Frank W. Zammetti
Founder and Chief Software Architect
Omnytex Technologies
http://www.omnytex.com
AIM: fzammetti
Yahoo: fzammetti
MSN: fzammetti@hotmail.com

On Tue, January 3, 2006 2:41 pm, Rick Reumann said:
> souravm wrote the following on 1/2/2006 11:34 PM:
>
>> The push will need to be initiated by an alert server or streaming
>> engine, which will keep pushing data (alerts) to the users's browsers.
>
> I don't believe that is possible unless you create some kind of Applet,
> but then you aren't really using the browser.
>
>> 2. What are the relevant technologies avaialble in Java/J2EE for this -
>> a) How AJAX an be used ?
>
> I'd use the buzz word Ajax for that. I only know the very basics of it
> thanks to Frank's info here:
>
> http://www.omnytex.com/articles/xhrstruts/ (download the sample webapp
> at the end of the article and you should be all set with the basics).
>
>
> --
> Rick
>
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>


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Re: Web Push Technology

[Rick Reumann <st...@reumann.net>]

souravm wrote the following on 1/2/2006 11:34 PM:

> The push will need to be initiated by an alert server or streaming
> engine, which will keep pushing data (alerts) to the users's browsers.

I don't believe that is possible unless you create some kind of Applet, 
but then you aren't really using the browser.

> 2. What are the relevant technologies avaialble in Java/J2EE for this -
> a) How AJAX an be used ?

I'd use the buzz word Ajax for that. I only know the very basics of it 
thanks to Frank's info here:

http://www.omnytex.com/articles/xhrstruts/ (download the sample webapp 
at the end of the article and you should be all set with the basics).


-- 
Rick

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