The do's and don'ts of Repository ties: suppliers who extend information model risk defeating the purpose of Case software bus

Software Magazine, March 15, 1990 by Peter Privateer

THE DO's AND DON'Ts OF REPOSITORY TIES

IBM's AD/Cycle announcement on Sept. 19, 1989 was not just another marketing event. It may have signaled the coming of age for computer-aided software engineering (Case).

The industry giant's endorsement of Case, and its associated development disciplines, puts the vast software development resources of IBM behind the effort to create an integrated computer-assisted environment for software engineers.

IBM acknowledged that it could not realize this vision alone. While the company announced it would supply the foundation of the AD/Cycle solution, it recognized that independent software vendors would furnish major components for the AD/Cycle strategy. Most Case vendors have since endorsed IBM's direction and stated publicly that they intend to develop AD/Cycle-compliant products.

What remains unclear is how Case vendors will use the AD/Cycle technologies to build these products. IBM has outlined some options available to tool builders, but vendors face several challenges in this undertaking.

IBM's Case direction prior to Sept. 19 had been the subject of much speculation; post-announcement, the industry has heard a plethora of views about what AD/Cycle means to the fledgling Case market. IBM describes AD/Cycle (Figure 1) as a framework for the application development process within Systems Application Architecture (SAA). While IBM talks about AD/Cycle as an evolutionary strategy, some observers believe that "... the long wait for the Repository will end in June 1990." (Moran, R., "AD/Cycle Starts Uphill Climb." Computerworld, Sept. 25, 1989, p. 1.) In other words, some see AD/Cycle as the product announcement for the long-awaited IBM "Repository." Perhaps the significance of IBM's announcement is in the eye of the beholder.

For many years the computer industry has talked about the need for a comprehensive repository (some used to call this an Information Resource Directory) that would provide information system (IS) professionals with a single place to store knowledge about an enterprise's information resources. This repository would not only serve as a database for application development information, it would also function as a corporate-wide data dictionary and data management tool.

Some industry pundits went so far as to say that this repository should provide application developers with central library management, configuration management and version control capability. When Case entered into the picture in the mid-1980s, the idea of a repository became associated with Case technology. One reason for this was the lack of integrated application development tools, which was seen as a major inhibitor to Case tool implementation.

People began to talk about a common software architecture and a central data store that would integrate multiple Case tools from multiple vendors. This common platform would function in much the same way as a standard hardware bus allows a user to plug multiple cards into a computer to get different functions. The notion of a common platform or "software bus" is seen by many as the answer to the integration problem.

While some vendors have achieved a common software bus for their own toolset, a common architecture between tool vendors remains an elusive target. To date, Case customers have attempted to achieve integration between different vendors' tools mainly through incongruent interfaces or largely ignored data interchange formats. It is generally acknowledged that a Case software bus can best be realized if Case tools all use the same database and data definitions.

Unfortunately, Case vendors rarely agree on much of anything, let alone the definition of a common database. Case customers have therefore looked to organizations like IBM which, because of their industry clout, could impose a de facto software bus standard. Many anticipate that IBM's Repository will provide the common architecture that will enable application development tool integration.

WHAT IBM SAID

Many observers misunderstood what IBM said on Sept. 19. These people believe that the requirements for a Case software bus and repository (a la what was talked about before Sept. 19) will be fulfilled in a product called Repository Manager/MVS. But a close look at what IBM said shows that the market requirements for a Case software bus and repository are really implemented by five key AD/Cycle technologies, collectively referred to as the Application Development Platform. Repository Manager/MVS by itself is not the intended interface for tool integration.

How tool builders interpret this aspect of IBM's announcement will materially affect the way they design and build AD/Cycle tools. In the section of the announcement called Application Development Platform, IBM stated:

"In order to facilitate tools integrating smoothly into the application development framework, IBM intends to provide a development platform consisting of five application development technologies. These technologies are: