POJO Mojo

This is the last in a three-part series of articles which examines the notion of object identity in a distributed cache. Terracotta DSO preserves object identity; traditional API-based cache services don't. This is a key differentiator for Terracotta and a big win for developers.

• Part 1 explains what object identity is and why preserving it in a distributed cache is important.
• Part 2 examines how domain modeling suffers when object identity is not preserved.
• Part 3 illustrates how DSO preserves identity in a sample application.

Overview

In part one of this series, we explored the notion of object identity and why it is an important consideration in developing distributed applications. In part two, we saw how most traditional replication frameworks do not preserve object identity and how this in turn can have perverse effects on application design. By contrast, Terracotta's DSO framework can be used to distribute an application in a way that is completely natural.

Now, we are going to explore in some detail how that natural model is presented to the developer. We will write some simple code that demonstrates how a developer using DSO can develop a domain model without having to worry about how it will behave in a distributed operational setting. The operational concerns come later, in a second step which involves making some simple declarations in XML.