Integration

I am doing research for a term paper on ERPs, and am currently studying the architecture of Oracle E-business suite.

I have understood that there is an Application server, which is made up of one or more Tablespace(s) that contain the data from some or all of the applications. In a way, it can be look at like a wheel with the server being the hub or center while each application is a spoke of that wheel.

Yet, I have been told that an application like General ledger only pulls information from certain applications. While an application like Accounts Receivable pushes and pull form/to multiple applications. Logically, I think that either multiple Tablespaces are used and certain applications can pull form one or more specific Tablespaces, or applications can only pull certain information from a Tablespace.

So, my question in the end is; how do the applications actually communicate if data is entered into an application and if it is edited? Thank you very much in advance.