Andreas Vogel wrote:
> What other languages do you have in mind? Smalltalk? Ada? Cobol? C?
Perhaps John could tell us what languages he was thinking of.
> Right. But Java (including EJB programmers) tend to fully exploit the Java features.
> So I expect lots of Java objects, collection classes etc in remote interface. For all
> these cases it's going to be hairy anyway. If you want to design for cross-language,
> you may start with IDL, generate Java from it and use the Java signatures in the
> remote interfaces.
It's hairy only if the mapping is not well-defined. Of course it is
not trivial to come up with a Java to IDL mapping that doesn't require
OBV, but I think it is well worth the effort. And I accept that in some
cases a mapping will not be possible, but customers looking for
interoperability will accept the inherent limitations of the mapping,
if it means they can avoid writing their own wrapper objects or
hiding the EJBs behind an XML message handler.
Our customers want interoperability of EJB components with CORBA
clients today. They don't want to wait until the vendors of their client
ORBs provide OBV support. So we have our own mapping of Java to IDL
which as much as possible tries to generate IDL struct & sequence types
from Java serializable objects and arrays.
Apart from all of that, the fact that OBV allows operations as well as
data types in valuetypes severely complicates the mapping for most
languages, since the implementations of a valuetype's operations are not
passed on the wire, and the mapping must define a mechanism for the
user to associate the operations with each valuetype they are using.
This will be probably no worse than using DII, but business customers
typically don't want to be coding at this level.
> Well, what other option do you have if you don't have Java clients or OBV?
Simple. You have your EJB server directly working with CORBA clients.
If the remote & home interfaces of an EJB are described with pre-CORBA
2.3 IDL (no OBV), then a CORBA client can interoperate directly with
the EJB server so long as the server supports IIOP.
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