Date: Thu, 22 Aug 2002 15:26:06 +1200 From: Calvin Varney <calvin@varney.org> To: Jonathon McKitrick <jcm@FreeBSD-uk.eu.org> Cc: freebsd-java@freebsd.org Subject: Re: Good distributed app technique for Java FreeBSD? Message-ID: <867kijfub5.fsf@ubana.varney2.org> In-Reply-To: <20020822012251.GA16283@dogma.freebsd-uk.eu.org> References: <20020822012251.GA16283@dogma.freebsd-uk.eu.org>
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Jonathon McKitrick <jcm@FreeBSD-uk.eu.org> writes: > Hello all, > > I'm trying my hand at some ideas for a distributed Java application. At the > moment, I'm considering a few possible solutions, but I'm not sure which > would would best on FreeBSD. > > Here is a brief example of what I would like to try as a proof of > concepts, based on a possible scenario: > >>>> > We have data acquisition instruments with a controlling host > computer. Imagine these in a lab, connected to the network. > > Somewhere else in the building, or perhaps even outside on the > internet, is a server that has the proprietary processing algorithms > that I could charge for by use. This web service would be > exposed to all customers, regardless of platform. Other companies could > even publish similar services as well. > > Now, imagine a scientist in their office in the first building. > They have an applet which connects to the component controlling > the instrument, gets the data, and sends it to the outside service > for processing. > <<< > > Would it make sense to make the instrument controller an EJB? How I don't know about making the controller an EJB as the spec states EJB's should not perform any direct i/o (i.e. no java.io.*) which is probably required for your instrument. Not all servers enforce this so it may be an option if you aren't concerned about portability. The Java Connector Architecture (JCA) defines a method for EJB's to communicate with external systems that may be of use, however don't know how easy this will be or what EJB servers other than JOnAS provide this support. An other option is to make your controller a normal java application that is a client to an EJB. This way controller app can inform the EJB of change in state/test results etc and the EJB server manage concurrent access to those results, scalability, security etc. If scientists need to send messages to the instrument this could be done by invoking a method on a session bean that in turn send a message to the controller app via JMS. > about the processing web service? Or should one or both be servlets? Would > Jini be better here, or maybe just plain RMI? > > I'm trying to balance flexibility with performance. At this point, I'm not > going to worry too much about the size of the data being transferred, though > that could become an issue for large data acquisitions. > > jm > -- > My other computer is your Windows box. > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-java" in the body of the message > > -- Calvin Varney To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-java" in the body of the message
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