DAML JBI TIE

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This page describes a Technology Integration Experiment (TIE) to apply DAML+OIL to the Joint Battlespace Infosphere (JBI).

This is an on-going effort. Initial plans for this TIE were described in a kickoff briefing. This page was added in January 2003.

Approach

We have sought to assess the value added by DAML+OIL and the Semantic Web to JBI. Expected benefits include richer metadata, simpler and more expressive subscription requests, and the ability to link to reference data and other Semantic Web content.

The work to date has focused on the Jini-based implementation of JBI Pub/Sub (1.1.8) as found in the CoABS Grid 3.3.1 release. We have layered on top of the existing API, without requiring any source code modifications. This has somewhat constrained our approach.

JBI InfoObject Ontology

We developed a jbi-ont.daml ontology (dumpont) to serve as the root of a DAML-based Information Object hierarchy. This incorporates various results from discussions of the Information Object focus group at the JBI Fall 2002 Meeting.

org.daml.jbi API

We have developed a simple org.daml.jbi Java API which encapsulates the mil.af.rl JBI API:

org.daml.jbi.Message (which should probably be renamed to org.daml.jbi.InfoObject) encapsulates a Jena model (collection of DAML+OIL statements). This ended-up being very similar to the org.daml.agents.Message class used in the SONAT Agents API.
publish and subscribe registrations and requests use org.daml.jbi.Message instances rather than XML
registrations on a class are expanded into multiple registrations on each of its subclasses.

org.daml.jbi currently provides only the interfaces we needed for experimentation; it could be extended to support the full flexibility of the mil.af.rl JBI API.

We hope to make javadoc for org.daml.jbi available on this site soon.

Class Subscriptions

Current JBI 1.1.8 Pub/Sub subscriptions specify a class (type) and a set of (invariant) instance values. DAML+OIL has the expressive power to express this and more within a class definition, specifically:

use of a daml:hasValue Restriction allows selection of a specific instance value
use of a daml:toClass Restriction with a user-defined XML Schema datatype allows selection of a range of instance values. This isn't supportable in the Jini implementation of JBI.

We have not yet implemented such Restrictions in org.daml.jbi. While it seems appealing to simply specify a class, defining a specialized DAML+OIL subclass requires roughly comparable effort to specifying an instance.

Example

To test and experiment with jbi-ont.daml and org.daml.jbi, we developed a simple events.java test application with the following features:

allows GUI configuration of 1 or 2 publishers and 1 or 2 subscribers each associated with a Class in the Info Object hierarchy
shows the messages sent and received by each component

For initial testing, we used a stream of genealogy events (Birth, Death, Marriage, Divorce) which were developed for a separate DAML scalability testing effort and recast as JBI Info Objects using gedcom-jbi.daml (HyperDAML). The captured screen image below shows execution of events.java with a subscriber receiving inputs from multiple publishers based on a superclass subscription:
events.java GUI screen capture
The events.java test harness could easily be generalized and applied to different applications.

Lessons Learned

hierarchies of Info Object types continue to appear to be useful
DAML+OIL continues to appear well-suited for defining Info Object type hierarchies
DAML+OIL continues to appear well-suited for expressing Info Object metadata (and optionally payload)
existing DAML+OIL ontologies can be easily turned into Info Object descriptions, as shown in gedcom-jbi.daml
DAML+OIL's extensibility readily allows the addition of platform-generated metadata (timestamp, size, etc.)
constructing a DAML+OIL graph using an API is arguably easier than generating well-formed XML (at least without a DOM serializer)
...

Possible Future Directions

investigate the expressivity and performance of the DAML Query Language (DQL) as a predicate language for JBI, by applying Stanford's implementation of DQL to representative Info Objects from a JBI application
upgrade the JBI-based SONAT Battle Damage Assessment (BDA) agent in the DAML Experiment to use jbi-ont.daml and org.daml.jbi
adapt org.daml.jbi to use the JBI Common API and/or the JMS implementation of JBI Pub/Sub
migrate from DAML+OIL to OWL
provide persistent storage and query of JBI Info Objects using DAML DB
...

Related Work

AT&T Government Solutions has developed Hot DAML Driven Information Push (HotDDIP) and Ontology Driven Knowledge Dissemination.

Author

Mike Dean

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