Knowledge Technologies International GBB (Generic Blackboard Builder)

The Dynamic Objects technology of Allegro CL's CLOS plays a pivotal role in the blackboard and agent-based software products developed by Blackboard Technology, now part of Knowledge Technologies International. The company's GBB (Generic Blackboard Builder) product, for example, was developed with Allegro CL. GBB is an object-oriented environment for developing high-performance software applications using the leading-edge "blackboard" metaphor.

According to Dr. Daniel Corkill, President of Blackboard Technology, Allegro CL's Dynamic Objects technology through CLOS (the Common Lisp Object System) provided a number of key advantages. For instance, CLOS's support for multiple inheritance was a necessity for creating libraries of blackboard-object capabilities that could easily be mixed together to develop application objects.

"GBB was designed to deliver all the dynamic capabilities of CLOS to developed applications," Corkill comments, "These capabilities include object-based abstraction and encapsulation, multiple inheritance, and a choice of dynamic or static typing."

Also crucial was the extensibility of CLOS, which allowed Blackboard Technology to implement the GBB "language" on top of CLOS, thereby providing a well-developed product language to GBB application developers.

"GBB provides a smooth extension of Common Lisp and CLOS, with blackboard-specific language capabilities augmenting the base language. As a result, GBB applications inherit all of the advantages of CLOS's Dynamic Objects capabilities, and these capabilities are especially important in blackboard-based applications."

"In terms of product maintenance and enhancement," Corkill adds, "Dynamic Objects allow us to provide software updates and bug fixes that can be easily sent by email or downloaded from the internet. Even if these updates involve changes to GBB's internal classes, they can be automatically loaded and incorporated into the user's environment."

Allegro CL's wide range of hardware platform support was another advantage.

"The ANSI CLOS standardization eliminates many hardware platform and software vendor dependencies," says Corkill, "This allows us to support GBB on a large number of configurations with low support and maintenance costs."

The Blackboard Metaphor

The blackboard approach is a powerful means of flexibly combining separate software systems and modules into a single integrated application. GBB provides a flexible "brainstorming" style of interaction to software applications, the same kind of brainstorming capabilities that makes groupware connectivity among people so popular.

The advantages of a blackboard include separation of knowledge into independent modules with each module being free to use the appropriate technology to arrive at the best solution with the most efficiency. An additional advantage of the independent modules is the potential for using separate computing units for the independent knowledge sources, thus allowing distributed computing. This approach allows for rapid prototyping of complex problems and simplifies long-term system maintenance.

Dynamic Objects are crucial in blackboard-based applications, where modules interact at runtime by posting results to the blackboard. Another module "knows" when a result that it can use is posted by dynamically adding a trigger to the other module's posting methods.

The RADARSAT-1 Project

Development projects that were previously considered too risky or expensive to undertake are being completed using GBB. This includes some efforts that are saving millions of dollars, such as in the case of the Canadian Space Agency, which reduced its RADARSAT Mission Control software development cost from an estimated $20 million to $7 million by using GBB.

"That's pretty dramatic in my book!" comments Larry Cochran of the Canadian Space Agency. In addition, the RADARSAT-1 system is up 24 hours a day, pulling in requests from around the world, and has not missed one product delivery since the first day of operation.

Blackboard Technology's Corkill sums up the advantages of GBB made possible by Allegro CL and CLOS: "GBB's use of Dynamic Objects technology gives GBB-based applications the flexibility needed to operate effectively in fast-paced, open, dynamic environments."

KTI can be found on the web at http://www.ktiworld.com.