Databases Reference
In-Depth Information
Entity variables within a BPEL process appear almost like any other variable defined
within the process. The key difference is that the variable is actually bound to a
remote SDO. This allows you to work with a remote data as if it were local.
This has a number of advantages, including:
•
If you update an entity variable within a BPEL process, then the remote data
is automatically updated.
If the remote data is updated outside the scope of the BPEL process
(for example, while the process is paused waiting for a callback), then the
next time the BPEL process references any values within that variable,
it will receive the updated version.
Remote data is accessed within the same transactional context as the BPEL
process, allowing you to modify data within the BPEL transaction. This can
simplify error handling, because if a BPEL process is rolled back, any changes
to the remote data will also be rolled back.
•
•
Implementing a Service Data Object
For our purposes, we are going to create a ListingSDO based on the following two
database tables in the oBay schema:
•
•
Listing
: Holds details of an item put up for auction on oBay
Bid
: Holds details of all bids placed against an item
These tables are installed as part of the oBay schema created
during the process of installing the sample oBay application.
Please see the oBay installation guide for details.
We will first look at how we can use Oracle ADF to create and deploy our ListingSDO,
and then look at how we can use the SDO within our composite application.
Overview of ADF Business Components
Oracle ADF provides a standard-based Java framework for building enterprise
applications, and is architected around the Model-View-Controller pattern
(discussed in
Chapter 10, oBay Introduction
).
Within this framework, the ADF model layer is used to bind to the underlying
components, which implement the business services so that they can be implemented
using a variety of technologies, including SOA composites, web services, and
Enterprise Java Beans (EJBs). One of the core technologies ADF provides for
implementing these business services is
ADF Business Components
(or
ADF-BC
).
