Calling one WTC service from another WTC service

Question

Hi,
We have a service called COLLECT defined in our WTC server.
Recently we've added a second service called SUM in the same WTC server.
We were wondering if it's possible to call SUM from COLLECT, and if it is, what configuration changes should be made in order to do it?
Currently both services are exported by the WTC server (and imported by our Tuxedo).
Thanks,
Shy

Answer 1

Hi Shy,
Although I haven't tried it, I'm fairly certain you cannot call a Tuxedo EJB using tpcall() within a WTC based application. What I normally advise customers to do when writing a Tuxedo EJB is to implement two separate interfaces. One is obviously the TuxedoService interface that all Tuxedo EJBs must implement. In particular you must implement the service() method that accepts a TPServiceInformation instance that provides access to the typed buffer passed to the EJB. Normally one then extracts the necessary fields or information from the typed buffer, performs whatever necessary business logic needs to be performed, and then constructs a reply typed buffer.
What I recommend is that you separate out the business logic into a separate interface and have your class implement both interfaces. The service() method would only deal with the marshalling/unmarshalling of the information contained in the typed buffers, and leave all business processing to methods on the second interface. Then if you need to access another "service", you would use the second interface, thus saving you from all the typed buffer manipulation.
So in your case, the business logic in the second interface of the COLLECT implementation would simply call the SUM implementations second interface (the EJB's business logic) instead of trying to call a Tuxedo service. While this helps in reuse of the business logic, it doesn't address the issue of trying to transparently move a service implementation from say Tuxedo to WLS. If that's what you are trying to do, you might try exporting the SUM service from WTC to the Tuxedo domain gateway, and then importing the SUM service from that gateway. This would likely cause a network round trip if it works, but it's something to consider.
Another alternative is to use something like the Apache Tuscany/Java project and build your Java applications using SCA. Tuxedo SALT includes a Tuscany/Java binding extension that allows Tuscany/Java applications to transparently call Tuxedo services. The choice of whether to actually call a Tuxedo service or call a Tuscany/Java based SCA service is determine by the binding selection and not changes in your code. Just a thought...
Regards,
Todd Little
Oracle Tuxedo Chief Architect