D4J's intent is to map Dialogic resources to classes, in order to build on top of them whatever system you may want to.
It's the first and second layer of an architecture for IVRs, the third being EWD (not included), where:

1st layer: dialogic API access, via JNI, all inside class local.dialogic.Dialogic.
2nd layer: Resource model classes.
Some are support related to Dialogic's own API, like local.dialogic.IOTT or local.dialogic.TPT.
Some are telephony world objects, like local.dialogic.Call.
3rd layer: configuration and resource allocation
4rd layer: real application.

Although EWD is being developed in parallel, D4J should be enough to build other architectures on top of it,
and we are using it as a free JTAPI implementation base.

Some links:
Project home (SourceForge D4J's project)
Mailing list (D4J's interest list)
Free JTapi (A project to develop a free JTapi provider)