Shops sample C/S OLTP, but keep bread-and-butter apps under wraps - early users of client/server transaction processing monitors usually start with noncritical systems

Software Magazine, Dec, 1994 by Brian Riggs

"TP monitors simplify complex applications and complicate simple applications," said Roy Schulte, Gartner Group's vice president of software management strategy and author of the report.

Schulte considers TP monitors in distributed computing a "fairly arcane technology" that will take an increasingly important role in client/server computing. "It requires an amount of sophistication on the part of the buyer, so the industry has been relatively slow in putting big [TP] applications on Unix," Schulte said.

"The only kinds of companies that will invest in [distributed OLTP technology! are large ones that already have some pre-Unix TP software like CICS," added Schulte. Those that do, he noted, will benefit from investing in CICS for Unix, because they will be able to take existing mainframe transaction processing applications, move the source code to Unix, and run the applications with relatively minor changes. He added, however, that some organizations are reluctant to move to Unix-based CICS, rationalizing that if they stay with CICS, they may as well stay in the MVS environment.

If a company decided not to go with CICS for Unix, and instead goes with another monitor, such as Tuxedo or Encina, it would have to "throw away all application designs and start over," Schulte said.

On the plus side, he continued, Encina has a few technological features a that CICS does not have. Schulte pointed to a nested transaction feature in Encina that "is helpful in a distributed system." A nested transaction is a group of subtransactions with identified starts and commits. With this approach, if part of the subtraction fails, the overall transaction does not fail; instead, the failed subtransaction is sent later. Because object-oriented technology consists of many pieces of reusable code, a feature like this is necessary in TP applications based on C.

"Programmers can get into a religious war over whether or not CICS APIs are better" than Encina's, Schulte said. In the end, he commented, the difference lies in which language the programmer is most comfortable with. "If they write in Cobol, they will feel more comfortable with CICS. But if they are more comfortable with C, Encina would feel more natural," he said. While programmers could write in C for CICS, the resulting application would be an amalgam gam of two languages that would ultimately be awkward to deal with

Overall, Schulte said, migrating TP applications to Unix does not necessarily improve them. "It just puts them on Unix," he explained. Generally performance does not suffer. It is cheaper in terms of hardware, "because mainframes are still overpriced," he said.

Among the operating systems on which distributed TP monitors run today, UNIX and NT are by far the most common, with NetWare and OS/2 coming in a distant second. "NT and Unix are almost interchangeable here. Almost all people running Unix are using NT as a secondary environment," Schulte said. "By 1997, NT will be as functional as Unix is for these kinds of things.