Re: Opening ServerSocket in EJB

Tom Anderson <>
Mon, 30 Mar 2009 19:40:12 +0100
On Mon, 30 Mar 2009, mk wrote:

Is it possible (and sensible) to open ServerSocket in one of EJB? My web
application (realized in JEE) needs to establish TCP connection with
external application. Data exchange with this application is sometimes
initiated by the application and sometimes by web application on JEE

I don't know if it will work - i believe the EJB spec bans the use of
Socket and ServerSocket from EJBs. However, there's a vague chance it will
work, and if it does, i imagine opening a server socket right from an EJB
will be the simplest way of solving your problem. However, it's naughty,
since in J2EE, managing sockets and so on is the app server's job. But ...

Maybe you have some other suggestions what kind of technology I should
use to establish connetion between client aplication and web application
on JEE server?

.... that's the trouble. I'm not aware of a standard, portable way of
adding application-layer protocols to app servers.

The closest thing i can think of is the J2EE Connector Architecture, one
of the more arcane and mysterious corners of J2EE. You'd write a JCA
resource adaptor to handle the connection, configure an instance of it in
your app server, and use that from an EJB, just as you'd use a database
connection or message queue. Even JCA has no bearing on server sockets,
but i believe that in a resource adaptor, you're allowed to manipulate
them directly, which you can't do from an EJB.

However, i just had a read of the JCA spec, and i got two thirds of the
way through before going stark raving mad, so i'm not sure this is a
productive approach.

You could consider using JMS at the EJB, and then writing a little
standalone server app which would mediate between the external app and a
JMS queue. This is also not pretty, though.


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