singletons & servlets...

[Dave Brown]

Hi all,

I have a question whether I'm approaching something with the correct philosophy..

In my web app I want to add a socket listener, so certain devices belonging to customers can connect via sockets rather than keep sending http requests as at present..

What I also want to do is allow them, when logged in to see that their device is in fact connected via a socket and let them do certain things..

My puzzle is the approach for the socket listener.. My plan was to have a SocketListener servlet which loads on startup and sits listening.. I suppose it doesnt have to specifical be a servlet but a plain old class, but I want to it to definately start when the webapp starts.. thats why I thought a servlet would be a suitable approach..
And as I said I need to be able access the class/servlet in a singleton fashion so I can check whats connected to it and other functions..

Has any thoughts they could share ?

[Colin Shine]

You could use a class implementing the ServletContextListener interface. It can be a regular class. Configure it in web.xml as:

  
<listener>
<listener-class>foo.MySocketListener</listener-class>
</listener>

[Ulf Dittmer]

A better approach would be to use a ServletContextListener (some info here under "Lifecycle events"). Using servlets loaded st startup for this kind of thing is kind of an abuse of servlets.

[Dave Brown]

Thanks guys, thats exactly what I need.

Dave