John Hunt wrote:
Dear All,
I have a question around SCA and Java embedded in a database. How
feasible is it to embedded SCA within say the Java VM running within an
Oracle database, either to provide a service or as a client to call a
service.
I have a scenario in mind that goes essentially like this:
1. Some database logic (e.g. PL/SQL) calls a piece of Java code
2. Java code needs to call out to an external service – for example
to access an external Work Order system to obtain a new work order id
3. Java code calls an SCA client, using (say) the Web Services
binding to access the remote service direct from within the database
4. Obtains a new id back and continues?
Obviously the Database JVM must be able to support the appropriate
version of Java etc. but what else might be required.
I think it's an interesting scenario. We could run SCA compositions
inside a database server, which would become just another node in an SCA
domain.
Nothing else is required, embedding an SCA runtime in your JVM should be
easy, you'll just need to do what most of our J2SE samples do to
bootstrap an SCA runtime and load it with your composite.
Potentially hosting services is more of an issue – however, in some
cases it might be useful to define a Java POJO that will invoke PL/SQL
within the database for performance issues (obviously we could create a
POJO external to the database that could call the PL/SQL / stored
procedures externally).
Yes exactly, the POJO could just perform local calls to the database
PL/SQL or stored procedures.
However, I suspect that this is a rather more
problematic area. For example, depending upon the binding selected what
functionality is required in the database - how would a web service, rmi
or jms binding be supported (if indeed at all).
I don't see any big problems here :) you just need to place the Tuscany
binding extension on your classpath, RMI, WS, JMS should just work
as-is, as in our J2SE samples, then you just add the desired binding to
the service implemented by your POJO, in your composite file. That's all.
In terms of real world scenarios I know of numerous situations in which
the SCA client in the database scenario would be very useful. I have
less “real world” scenarios for the service in the database example.
But should the ability to at least run an SCA Client from within the
database be a supported SCA scenario? I would be very interested to know
what the SCA Dev community think about this.
Regards,
John
I think it's a very interesting scenario and we should support it!
Do you want to start working on it? Do you need pointers to the samples
that bootstrap the runtime or have you already played with them?
--
Jean-Sebastien
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