Chapter 8. Transaction Technology

Why, a four-year-old child could understand this report. Run out and find me a four-year-old child.

”Groucho Marx, Duck Soup , 1933

Today, programmers have access to various commercial technologies to build distributed, transactional applications. These technologies are typically based on either synchronous remote procedure calls (RPC) or message queues. RPC-based technologies or products are normally associated with a distributed-transaction model. Message queue “based technologies or products are more commonly associated with a queued-transactions model. Both of these models are described in detail later in this chapter.

It is often difficult to determine when a particular model is appropriate or inappropriate. The answer is not always intuitive and often requires careful examination. This chapter provides some answers and guidance for selecting the appropriate model. However, because the choice of model goes hand-in-hand with the choice of a technology that implements it, we must consider such qualities as the reliability, usability, and maintainability of the commercial products that support particular transaction models. For example, in an incremental modernization effort, such as RSS, transactions may span legacy and modernized components on two different platforms. Which is the best model and the set of technologies for this situation?