I am going to try one last time to address this confusion.
The original post was about using EJB over RMI vs. CORBA.
EJB specifies RMI like syntax for remote/home interface definitions,
but it is protocol neutral. An EJB server takes the home/remote
interfaces and bean implementations, and generates all the needed
underlying protocol machinery. This might be iiop stuff jrmp stuff,
joe's protocol stuff, whatever. To the EJB programmer it is transparent.
This of course changes if you are programming directly to RMI or CORBA
idl, which is I think what your post is getting at.
Signing off on this topic,
-Chris.
> -----Original Message-----
> From: Rainer Kerth [SMTP:[EMAIL PROTECTED]]
> Sent: Thursday, March 04, 1999 1:15 AM
> To: [EMAIL PROTECTED]
> Subject: Re: IDL from EJB
>
> I would not be too optimistic about the possibilities of switching the
> transport infrastructure transparently. RMI and CORBA differ in several
> important ways:
>
> - IDL, if compared to RMI, gives you only a rather limited interface to
> your
> object (e.g you can't write a distributed propertyChange method with a
> *real*
> Java event parameter in CORBA - you have to use a struct.). In RMI you can
> use
> all Serializable types in Interfaces.
> - CORBA does not allow for downcasting of remote stubs. (you have to use
> narrow, and you loose the object identity in doing so). RMI does.
> - CORBA does not guarantee the object identity of remote references (i.e.
> two
> references to the same remote object need not be identical wrt ==; you
> have to
> use isEquivalent). RMI does.
> - CORBA does not allow for overloading of methods. RMI does.
> - CORBA cannot transmit null parameters. RMI can.
>
> CORBA is certainly a great way of doing distributed computing, with a long
> (well - relatively long) history of successfull implementations. But you
> have
> to pay a price for language independence. RMI over IIOP is only in beta so
> far.
> It is interesting but the points mentionned above concerning downcasts and
> object identity apply to RMI over IIOP as well.
>
> IMHO it will be rather difficult to port an existing RMI application to
> CORBA.
> If you want to go for CORBA, do it right away. Wrapping the CORBA code in
> a
> thin Java layer is possible (we did it in our current project) and gives
> you
> some nice features. It would probably require a considerable amount of
> work,
> though, and it is not a standard solution.
>
> Rainer Kerth
>
> --------------------------------------------------------------------------
> ---
> Rainer Kerth, Consultant
> EMEA Object Technology Practice
> IBM Unternehmensberatung GmbH
> Mobil (+49-171) 766 92 07, E-Mail [EMAIL PROTECTED]
>
> --------------------------------------------------------------------------
> ---
> Rainer Kerth, Consultant
> EMEA Object Technology Practice
> IBM Unternehmensberatung GmbH
> Mobil (+49-171) 766 92 07, E-Mail [EMAIL PROTECTED]
>
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