AppletTalk.com Java discussions newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Possibilities with RMI          AppletTalk.com Forum Index -> Java Help View previous topic :: View next topic   Author Message David Guest Posted: Sun Nov 20, 2005 2:29 pm    Post subject: Possibilities with RMI Hi, I've been reading up on RMI but am still unsure if the following is totally possible please advise, thanks. I'd like to basically have a RMI Server working on 1 or more clients, which connects to an overall server. I would like this server to send out various different objects that implement a set interface. I would like these sent over RMI, and processed on each client. The object then - or a resulting object being returned. Can this be done so that the RMI server on programmed into each client can contain no code about what it has to call on the objects, only use the interface methods, each object is guaranteed to implement? Thanks for any help in advance. David Back to top VisionSet Guest Posted: Sun Nov 20, 2005 2:39 pm    Post subject: Re: Possibilities with RMI "David" <david.goodyear (AT) gmail (DOT) com> wrote Quote: I'd like to basically have a RMI Server working on 1 or more clients, which connects to an overall server. I would like this server to send Yes, the server initiates the call on the clients yes? So atypical direction, the server must know what port the client is available on. Quote: out various different objects that implement a set interface. I would like these sent over RMI, and processed on each client. The object then - or a resulting object being returned. Can this be done so that the RMI server on programmed into each client can contain no code about what it has to call on the objects, only use the interface methods, each object is guaranteed to implement? RMI always works like this. You just extend Remote interface and objects you receive will be of this type. You can use an adapter object client side, if you prefer, to strip out the RMI specific RemoteExceptions. Or have I misunderstood? Mike W Back to top Roedy Green Guest Posted: Sun Nov 20, 2005 2:45 pm    Post subject: Re: Possibilities with RMI On 20 Nov 2005 06:29:45 -0800, "David" <david.goodyear (AT) gmail (DOT) com> wrote, quoted or indirectly quoted someone who said : Quote: Can this be done so that the RMI server on programmed into each client can contain no code about what it has to call on the objects, only use the interface methods, each object is guaranteed to implement? In RMI, both ends must be compiled against identical code implementing the classes. One end may end up using a stub, a class that has the same signatures with each method implemented as a remote procedure call. Serialization, upon which RMI is based, can't create objects unless the corresponding class file for them is present. So you can't for example receive a Dog object as a return value (or send a Dog object as a parameter for that matter) without the real Dog class being present in the client. One way to deal with pruning the list of classes in the client is to use genjar. see http://mindprod.com/jgloss/genjar.html -- Canadian Mind Products, Roedy Green. http://mindprod.com Java custom programming, consulting and coaching. Back to top VisionSet Guest Posted: Sun Nov 20, 2005 4:35 pm    Post subject: Re: Possibilities with RMI "VisionSet" <spam (AT) ntlworld (DOT) com> wrote Quote: "David" <david.goodyear (AT) gmail (DOT) com> wrote in message news:1132496985.204295.292230 (AT) o13g2000cwo (DOT) googlegroups.com... RMI always works like this. You just extend Remote interface and objects you receive will be of this type. You can use an adapter object client side, if you prefer, to strip out the RMI specific RemoteExceptions. Or have I misunderstood? Sorry if these opinions differ, I probably misunderstood. I'm talking about the remote objects themselves, these never actually leave the machine, RMI creates a stub at the other end that implements your Remote interface. Roedy is correct when talking about other objects. You could also, instead of a common jar, create one app that runs in two modes depending on the command line that launches it. -- Mike W Back to top Alex Molochnikov Guest Posted: Sun Nov 20, 2005 7:00 pm    Post subject: Re: Possibilities with RMI One small addition to what Roedy said: instead of having the required implementation classes packaged into the client's jar file and deployed with the client, you can keep them on the server side, and write a custom class loader to fetch them from the server when needed. This way the client will always get the latest version of the implementation. Alex Molochnikov Gestalt Corporation "David" <david.goodyear (AT) gmail (DOT) com> wrote Quote: Hi, I've been reading up on RMI but am still unsure if the following is totally possible please advise, thanks. I'd like to basically have a RMI Server working on 1 or more clients, which connects to an overall server. I would like this server to send out various different objects that implement a set interface. I would like these sent over RMI, and processed on each client. The object then - or a resulting object being returned. Can this be done so that the RMI server on programmed into each client can contain no code about what it has to call on the objects, only use the interface methods, each object is guaranteed to implement? Thanks for any help in advance. David Back to top Daniel Dyer Guest Posted: Sun Nov 20, 2005 10:43 pm    Post subject: Re: Possibilities with RMI On Sun, 20 Nov 2005 14:29:45 -0000, David <david.goodyear (AT) gmail (DOT) com> wrote: Quote: I'd like to basically have a RMI Server working on 1 or more clients, which connects to an overall server. I would like this server to send out various different objects that implement a set interface. I would like these sent over RMI, and processed on each client. The object then - or a resulting object being returned. Can this be done so that the RMI server on programmed into each client can contain no code about what it has to call on the objects, only use the interface methods, each object is guaranteed to implement? I'm sure you can do what you want with pure RMI, but it sounds like what your trying to achieve would be a suitable application for JavaSpaces. Take a look at these links, it might save you some work. The third one seems to be the kind of thing that you are trying to develop (correct me if I am wrong): http://java.sun.com/developer/Books/JavaSpaces/introduction.html http://www.javaworld.com/javaworld/jw-11-1999/jw-11-jiniology.html http://www.javaworld.com/jw-01-2000/jw-01-jiniology.html Dan. -- Daniel Dyer http://www.dandyer.co.uk Back to top David Guest Posted: Mon Nov 21, 2005 1:46 pm    Post subject: Re: Possibilities with RMI Hi, thanks to everyone for all your answers. JavaSpaces seems an ideal candiate to solve the problem. Im stil reading it all up now :S. Yet another question :- Does anyone know however, if the space can be run in an encryted link, without the need for servers with SSL certificates? Maybe if anyone has seen example code of this on the web somewhere as well? 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