concurrent users supported by tomcat

[PrasannaKumar Sathiyanantham]

Hai i have worked in tomcat for the past 3 months....

Can any one please tell me the difference between application server and web server......what is the difference between them.....

what is the use of ejb............

in my college we did a project on online exam(it allows the teacher to create questions and the students answer them...........) the only difficulty is that the tomcat(i used this) allows only 15 students at a time.....(what should i do such that more than 300 students must take the exam at the same time)

what will the advantage of ejb will be at this place...

will the result would have changed if i had used weblogic or jboss rather than tomcat........

Final question

i saw in one thread that if we use struts,spring,weblogic there is no need for ejb why is that

I know that i have posted a lot of questions...........(its just that i am new to this and my head is spinning with what to study and what to leave out) pelase tell me an order in which i must go through java..... in my office (i joined inautix recently) i am expected to work in weblogic,struts,spring,hibernate .......

please help me

[Misha Ver]

PrasannaKumar Sathiyanantham wrote:in my college we did a project on online exam(it allows the teacher to create questions and the students answer them...........) the only difficulty is that the tomcat(i used this) allows only 15 students at a time.....(what should i do such that more than 300 students must take the exam at the same time)

Have you already tried 16 students?

[Ulf Dittmer]

PrasannaKumar Sathiyanantham wrote:the only difficulty is that the tomcat(i used this) allows only 15 students at a time.

Can you elaborate what you mean by this? Tomcat doesn't really have a concept of simultaneous users, but it does have a limit of simultaneous requests (in the form of threads). Those can be configured in the TOMCAT_HOME/conf/server.xml file, and are usually set to 150 by default (I think). But that doesn't mean that 150 users can be serviced at any time - it could be substantially less (if the users are doing very time- and CPU-consuming things), or it could be substantially more (if the users send short, quick-to-fulfill requests). Also, not every user has a request pending at any given time, further increasing the number of users that can be serviced by a given number of threads.

[PrasannaKumar Sathiyanantham]

At a time if more than 15 students are writing a test it does not support .........(I used apache tomcat 6)

i will try that configuration you mentioned and thanks a lot

[Ulf Dittmer]

At a time if more than 15 students are writing a test it does not support

I still don't understand what you mean by that. Tomcat easily supports more users -and even more simultaneous requests- than that. What, exactly, ate those users doing, and what, exactly, is happening on the server?

[PrasannaKumar Sathiyanantham]

i dont know all those details. i am sorry

the only fact i found was that when more than 15 students were writing the text the apache tomcat doesnot add more users..

it is like this

everyone must login to attend the test

after 15 students it gives a message stating that more users cannot be supported...

[Ulf Dittmer]

What is "it"? What kind of message is that - an HTTP error? An application error? A DB error?

[PrasannaKumar Sathiyanantham]

when more than 15 students try to write the test then
after 15 students when the 16th student tries to login the server gives the following error as a new html page..


sever too busy to handle...

[Ulf Dittmer]

I can't tell from your reply what, exactly, is the cause of the message, but I can assure you that Tomcat can easily support way more users.

[Tim Holloway]

Tomcat doesn't even support the idea of "users" in the sense that something like a multi-user time-sharing system does. It leaves that job up to the individual webapps to define in whatever way they want to. Tomcat does support J2EE security contexts, but those aren't "users" except in the sense that they define how container-based security systems authenticate and authorize.

So in other words, Tomcat itself doesn't know or care how many users an app has. It will support as many requesters and it can provide resources for, and that figure will vary based on a number of factors, but it's usually going to be a LOT more than 15.

More likely, the webapp itself is programmer to limit the number of concurrent users. This could be someone using fixed-sized tables where a more open-ended mechanism would have been appropriate, or even - if you're running a commercial webapp - because you have to purchase a license to allow more users.

EJBs have their uses, although Tomcat doesn't support them. Spring/hibernate offer options that are similar, but can run in Tomcat and other places that EJBs originally couldn't. However, a lot of work has been done to consolidate that kind of stuff, so with JPA/EJB3, the differences aren't as great. Still, each technology has its place.