Java Database Connectivity (JDBC)

Dear Friends
I am not sure, whether this is the right forum to ask this question.

We are having a Java based ERP application and we are planning to use Oracle Financial for Finance side.
We wanted to integrate online.
For example, when i create a Purchase invoice in Java Application, we need to post a Purchase invoice in Oracle Financial.

And also the reverse integration.
For example
When i create a GL master it should be transferred from Oracle to Java application

I am sure, we need to some interface coding on both the applications.

My question, whether we can online integration.
Which is while posting from Java application, i should get the response from Oracle application, regarding the posting results

If Yes.
What are the pre-requesites
I mean, whether we need to buy a add on product to have the integration

Regards
Madhan D