11 Replies Latest reply: Aug 1, 2008 3:56 AM by 843851 RSS

    About DSM-CC APIs

    843851
      Hii everybody,
      i have a doubt in DSM-CC U-U APIs .....how we can differentiate which APIs use RPC mechanism??(if some body knows more specifically about org.dvb.dsmcc and org.dvb.net)
      one more, do all U-U APIs use IDL mechanism or only those APIs which use RPC will make use of IDL??

      thanks in advance
      renu
        • 1. Re: About DSM-CC APIs
          843851
          You're using some rather confusing language which makes answering your question a little hard.

          DSMCC was originally developed using CORBA to send messages over a conventional point to point, bi-directional TCP connection.

          The DSMCC object carousel was developed later and (I'm told) basically involves transmitting a serialized form of the CORBA messages originally sent via TCP.

          In theory the org.dvb.dsmcc API can address files via both the carousel / serialized form and the original form. The **same** APIs could use both mechanisms depending on things like the NSAP address passed to ServiceDomain.attach.

          In practice, the use of the API via CORBA / TCP is optional and isn't implemented. Hence the practical answer is that no APIs use the RPC mechanism or IDL.
          • 2. Re: About DSM-CC APIs
            843851
            thank you very much for the clear answer...
            we r planning to use the return channel(docsis modem).....bi-directional TCP.
            so can you guide how i can proceed further.
            • 3. Re: About DSM-CC APIs
              843851
              There are many ways of addressing the return channel without using DSMCC.

              java.net supports TCP sockets, UDP packets and may support HTTP.
              javax.net.ssl supports secure connections.

              If it doesn't support HTTP, there are implementations of HTTP in Java.
              You can use HTTP directly or put use a small XML parser to put SOAP on top of it.
              The most widely used small XML parser is nanoXML.

              What do you want to use the return channel for?
              • 4. Re: About DSM-CC APIs
                843851
                once again thanx a lot for the valuable info......
                we are planning to use it for applications like interactive gaming to send the controls back to the server.
                now i have a doubt from DSM-CC spec(ISO 13818-6),in the page 110 they have shown 4-Application and Service Interfaces.
                can u explain "Model C" a bit in detail with some real time example.
                • 5. Re: About DSM-CC APIs
                  843851
                  I can't answer questions on the DSMCC specification.

                  Using DSMCC for interactive gaming seems a little strange. Did you consider using java.net directly?
                  • 6. Re: About DSM-CC APIs
                    843851
                    we are using java.net .
                    i am not sure about interactive games using DSM-CC.what i am thinking is that the application downloaded(through object carousel) may specify the return path via DSM-CC....is it correct?? if not then what decides the return path either via DSM-CC or HTTP/UDP??
                    it will be more useful for me if you can explain about this.
                    thanks in advance for the nice reply i am going to get.
                    • 7. Re: About DSM-CC APIs
                      843851
                      (Disclaimer: this is typed form memory and I haven't had time to check it properly. I may be wrong about this!)

                      The DSM-CC specification can be very confusing when you're talking about broadcast networks, and it's best to read it together with the DVB data broadcasting spec to get a better idea of what can be used.

                      The main DSM-CC specification assumes a two-way network, which you can't assume in a broadcast network. For this reason. most broadcast systems do not support the use of DSM-CC for two-way traffic. In a two-way network, DSM-CC acts much closer to a remote procedure call mechanism, which is what the models you refer to are discussing. In a broadcast network, the objects are actually downloaded to the client and are manipulated locally, so they can't be used for communication like this.

                      In the case of an MHP/OCAP box, you should use java.net for all communication with other machines. This will always be carried out via an IP connection over the return channel rather than using DSM-CC. So the short answer is, DSM-CC will never be used for return path communication in a JavaTV environment.

                      Steve
                      • 8. Re: About DSM-CC APIs
                        843851
                        DSM-CC can be used for return path communication because DSM-CC spec says about User-User interface where a client can operate on the remote server objects.DSMCC spec is transport independent and for return channel usage DVB specifies the use of IIOP which is a version of GIOP. In IIOP the messages are carried over TCP/IP and hence java.net package is used for carrying IIOP.

                        mkm
                        • 9. Re: About DSM-CC APIs
                          843851
                          we are using java.net .
                          Good.
                          i am not sure about interactive games using
                          DSM-CC.what i am thinking is that the application
                          downloaded(through object carousel) may specify the
                          return path via DSM-CC....is it correct?? if not then
                          what decides the return path either via DSM-CC or
                          HTTP/UDP??
                          Support for the return path via DSM-CC is optional.
                          As far as I know, nobody has implemented this option.
                          I **strongly** recommend you forget all ideas of using
                          DSM-CC with the return path.

                          To use the return path, all your application has to do is create
                          a java.net.Socket.
                          it will be more useful for me if you can explain
                          about this.
                          thanks in advance for the nice reply i am going to
                          get.
                          • 10. Re: About DSM-CC APIs
                            843851
                            Hi All,
                            We can think of two kinds of interaction for an application.
                            1) An application that resides on the client may want to communicate with the server. (For eg., a game application in the client may wish to upload the score onto the gaming server)
                            2) The application itself can reside on a remote server. The client while running the aplication is in fact invoking methods on the objets residing in the server.

                            Now my understanding is that, for the first scenario, the application just needs to open a socket and send the score to the server. ( using java.net). This is the return channel that we have been talking about in this thread so far.
                            DSM CC API also supports the second scenario, of accessing remote objects via the RPC mechanism. DSMCC spec specifies a SII ( Service interoperability Interface) with a one to one correpondence with the APplication portability Interface that is visible to the application.

                            The doubt i have is while implementing MHP/OCAP, do we need to support the RPC mechanism? Or are we definite that the applications that will ever run on an MHP/OCAP terminal will always be broadcast using broadcast network and hence is available locally?

                            Hope the query is clear and hoping to see a response!
                            • 11. Re: About DSM-CC APIs
                              843851
                              where can I find iso 13818-6,

                              It is not available @ ETSI

                              please mail me either download link or the pdf itself.

                              subhanshoo@gmail.com

                              Thanks in advance.