IBM's DRDA paves way to interoperability; but work remains for IBM, third parties to achieve cross-platform RDBMS access - IBM's Distributed Relational Database Architecture client/server architecture for accessing remote relational data

Software Magazine, Nov, 1993 by Barbara Francett

"However, with large amounts of data, the gateway was slower in our tests," he explained. As a result, the configuration he will recommend to Bellcore's development groups will be a high-powered server linked to the mainframe by a TokenRing with 16-Mbit bandwidth to offset the time required for communications.

One kind of application these groups would be developing is analysis tools for traffic engineers, Thomas said. "Traffic engineers examine traffic data in the telephone network and analyze where capacity needs to be added. They need to be able to interactively browse through analysis reports and, when necessary, go back to the raw data."

An industry-standard protocol for database access will expedite these tasks. "We are excited about the DRDA protocol, because it provides multivendor access to mainframe data from PCs and workstations," Thomas said. "It will allow users to maximize the value of their mainframe data."

MORE SUPPORT COMING

Other RDBMS vendors are also working to add DRDA support to their gateways or to develop products supporting DRDA. The Ask Group has added DRDA1 support to the Ingres/Gateway to DB2.

"The Gateway to DB2 uses DB2's call attach facility [an API that allows access to DB2]. We have expanded that to take advantage of the application requester services in DB2," said Ann Cowan, director of connectivity development. The company also plans to begin working to support DRDA2, she added.

Extensions to DRDA that the firm is looking forward to, Cowan said, include support for Transmission Control Protocol/Internet Protocol (TCP/IP). DRDA today requires LU6.2. "This will be an advantage, from our point of view, because many Unix environments are TCP/IP," Cowan said. "The SNA protocol is a burden." Tools that will make DRDA more accessible are also needed, she added.

Sybase plans to offer an OmniSQL Access Module for DRDA in the first half of 1994, said Steve Knowles, director of interoperability solutions. This is an addition to the current OmniSQL Gateway product, which provides several capabilities that DRDA outlines, Knowles said. These include distributed joins and translations between SQL dialects.

Such overlaps are part of the reason some RDBMS vendors have been less than enthusiastic in implementing DRDA support. And, in some respects, DRDA conflicts with Sybase technology, according to Knowles. This complicates a support effort. For instance, he explained, SQL statements can be executed either dynamically or compiled ahead of time and run at execution. In DB2, precompiled SQL would be stored as a separate load module and executed from an application program, Knowles said.

"Sybase has no concept like that," he said. "Sybase would handle it as a stored procedure and execute it by remote procedure call [RPC]. The initial version of DRDA has no concept of RPC, which is very important to Sybase."

Like the Ingres/Gateway to DB2,

SQL Connect Gateway to DB2 from Oracle Corp. uses DB2's call attach facility for access to DB2. "In some ways, SQL Connect duplicates what DRDA does," said Gary Bloom, vice president of the IBM product line division at Oracle.