Servlets store information on the server side?

i am working on a tapestry web app.
is there a way for servlets to store some information on the server side independently. like a http session is visible to only the user who is viewing it, somebody else cannot view somebody elses http session details. but is there a way to share some common information inbetween all user sessions/pages. i dont want to store any info within the db but somewhere within tomcat.
i hope i am able to express my question properly.

I am a little confused when you say:
A user logs onto the server and a new web application is started for him then another user logs on from another place and a new web application is started for that user.
If they are hitting the same servlet in the same context (directory under your root webapps folder) then there is one web application. Each user is just starting a new session in that one web application. Each user is not creating a new web application.
That being said, and if it is true (all the users are using the same servlets) then you should use the ServletContext to store data you want to share between users. That is what it is designed for. In Servlets (and JSPs) you can talk about four different scopes where data gets stored in a particular application:
1) The 'page' scope is relevant only to JSPs, and represents data that is visible only to the current JSP page for the current user. The object used is called PageContext.
2) The 'request' scope stores data available to all servlets accessed by a single user through a single request (so if forwards, or includes are used to get from one servlet to another). The ServletRequest object is used to store this data.
3) The 'session' scope stores data available to a single user across multiple requests. The HttpSession object stores this info.
4) The 'application' scope stores data available to all users across all requests. The ServletContext object stores this info.
All of the scopes have data stored/retrieved via setAttribute(key,value) and getAttribute(key) methods.
"cant i maintain a list of users who are generating or viewing a web app from my server at any instance"
Yes you can. I would use a SessionListener to listen for when new sessions are created. When they are get the information you need and add them to a list in the ServletContext where all users can see it. Then in the SessionListener listen for when a session is destroyed, and remove the user from the list.

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Hi,
Can we refresh a servlet page on the server side without using response.sendRedirect()???

Hello,
I just had a look at www.pushlets.com, looks an interesting idea, and relatively easy to do.
Correct me if I am wrong, but the examples I looked at were not reloading the page, rather, they create a page that takes a long time to load, and keep streaming more data to it.
What they are doing is putting the thread to sleep, so the page never loads fully, instead continually updating.
The problems with this would seem to be that you could append more data to the page, but not be able to delete information already in the browser.
I am also unsure what would happen in the event the user closes the browser, I assume the jsp would keep trying to send data until the session expired.

Why the server side behavior of LoadVars() not consistent?

In my server side script for FMS app,there is such code:
var lv = new LoadVars();
var params = new LoadVars();
lv.send("http://mysite.com/registerVideo.php", params, "POST");
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Oops,why this feature has always worked like charm for me only??
Below is the server side request caught from firebug:
POST registerVideo.php
http://mysite.net/registerVideo.php
200 OK
mysite.net
115ms
ParamsHeadersPostPutResponseCacheHTML
Response Headersview source
Server
nginx/0.7.67
Date
Tue, 29 Mar 2011 14:45:31 GMT
Content-Type
text/html
Transfer-Encoding
chunked
Connection
keep-alive
Vary
Accept-Encoding
X-Powered-By
PHP/5.2.14
Expires
Thu, 19 Nov 1981 08:52:00 GMT
Cache-Control
no-store, no-cache, must-revalidate, post-check=0, pre-check=0
Pragma
no-cache
Content-Encoding
gzip
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Accept-Encoding
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ISO-8859-1,utf-8;q=0.7,*;q=0.7
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How to delete the server side sessions

Hi All,
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If yes then how can i do it.
Any help will be very usefull.
Thanks well in adavance.
Shrikant

Shrikant:
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Hi all,
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Before I go into detail in the error we get I will first describe our landscape. All the configuration we did was done in debate with SAP.
We use the SAP Solution manager (ehp1 SP 4) as the CTS+ server as recommended by SAP and have an NWDI system of which we only use the components DTR and CBS (since CMS is not used anymore in the activity based transport). We have defined three logical ports/RFCs. CTSCONFIG points to the NWDI system. CTSDEPLOY is running on the java stack of the solution manager and is only used for portal content (=epa) transports. CTSDEPLOY_DI is pointing to the NWDI system and is used for all NWDI (=dip) changes. The NWDI is running ehp1 SP3.
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Kind Regards,
Nico van der Linden...

Hello Nico,
I would need the java trace files to get more info on this issue, but you can start troubleshooting this error with these notes:
#1172252: CTS+, 'attach file': Troubleshooting Guide;
#1003674: Enhancement for non-ABAP systems in CTS;
#1155884: CTS+, configuration 'close coupling': Troubleshooting guide;
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Note #1003674 is a must for any CTS+ systems to work properly, as well as having an updated version of the transport programs (tp and R3trans).
Lastly, note #1155884 goes through some JCoException exceptions that commonly take place during CTS+ transports. But again, you need to check the underlying trace files to find the root cause of your issue.
I hope this information helps.
Best regards,
Tomas Black

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In the process of creating Breacrumbs for our website
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Ignore the JSRs for now.
Follow the JavaEE tutorial.
http://docs.oracle.com/javaee/6/tutorial/doc/
The answers to many of your questions will be clear to you once you have completed the tutorial.
I also like the tutorials here (they are a little dated, but still mostly relevant as the core JEE6 specs that the tutorial relies on were released over 5 years ago and JEE7 is yet to be released).
https://schuchert.wikispaces.com/EJB+3+and+Java+Persistence+API
zonski has a spring+javafx focused tutorial if you would prefer to learn and use Spring than JEE (they are differing technologies which cover pretty much the same functional set):
http://www.zenjava.com/series/building-jee-applications-in-javafx-2-0/
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A lot of the stuff can be learnt and used in isolation.
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Java Servlet Technology: http://docs.oracle.com/javaee/6/tutorial/doc/bnafd.html
JAX-RS web services: http://docs.oracle.com/javaee/6/tutorial/doc/giepu.html
Contexts and Dependency Injection: http://docs.oracle.com/javaee/6/tutorial/doc/gjbnr.html
Enterprise Beans: http://docs.oracle.com/javaee/6/tutorial/doc/bnblr.html

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Hi Robin,
Thanks for the detailed explaination.
This may sound silly to you but I've another doubt which is as follows:
As you mentioned that the external web application will be sending requests to our Web service(in SOAP envelopes) and rest of the functionality can be achieved by our web service.
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Thanks & Regards,
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By the way, we actived our BEX service at the SICF.
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Hi
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Regards

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Thank you for replying.
Edited by: user4592285 on 2012-10-18 上午6:48

Hi,
As Gurus suggested, you will have to restrict viewing of data through dimension level security.
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Edited by: 918547 on Oct 18, 2012 8:40 PM

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hi all;
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http://www.devwebsphere.com/devwebsphere/2006/04/ajax_and_its_im.html
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Sergey : http://jsfTutorials.net

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When I sing, it is usually Girls On Film or Hungry Like The Wolf but I know that Percy Blakney has a fondness for Haircut 100.
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Hi,
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Regards,
Simon Wu
TechNet Community Support

Servlets store information on the server side?

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