As mentioned in previous posts, the client to the EJB's can be
multi-threaded (assuming that the client itself is not an EJB... as pointed
out by Ian). So you could have a multi-threaded "monitor" that talks to the
beans its monitoring on a scheduled basis. An EJB server that lets you chose
how various services are activated an co-located would be advantageous.
I'd be careful with polling based protocol here if you need to scale this
up! You might also want your beans to push events to the monitor when
certain state changes occur, and use polling as a stop gap when events
aren't received within a time band.
Once again we see we need to mix the EJB model with other models that are
asynchronous for certain applications.
-Chris.
----------------------------------------------------------------------
Chris Raber, Director Professional Services, GemStone Systems Inc.
100 West Big Beaver, Suite 200, Troy, MI 48084
phone: (248)-680-6691, fax: (248)-680-6689,
email: [EMAIL PROTECTED]
web: http://www.gemstone.com/
----------------------------------------------------------------------
> -----Original Message-----
> From: Fredrik Jonsson [SMTP:[EMAIL PROTECTED]]
> Sent: Thursday, October 21, 1999 9:41 AM
> To: [EMAIL PROTECTED]
> Subject: Monitoring state
>
> Hi,
>
> In our project we want to add monitoring functionality to our system,
> e.g. supervising the states of specific objects. The purpose can be to
> recognize if an object's state is invalid at a certain time, where the
> application has to respond to that situation in some way or another.
> This is normally implemented with monitoring threads. In EJB you're not
> allowed to use threads. So, how would you implement this instead. Should
> you write an ordinary Java application, implemented with threads,
> outside the container to monitor the state? The Java-application act as
> a client to the EJB server. A typical example in our applications is
> that certain information must be set within a specific time. Otherwise,
> the application must notify appropriate users.
>
> -Fredrik
>
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