Online processing on the mainframe

In other sections, we discussed the possibilities of batch processing–but those are not the only applications running on z/OS and the mainframe. Online applications also run on z/OS, as we show in this section. We also describe what online, or interactive, applications are and discuss their common elements in the mainframe environment.

We examine databases, which are a common way of storing application data. Databases make development easier–especially in the case of a relational database management system (RDBMS)–by removing the burden from the programmer organizing and managing the data. Later in this section, we discuss several widely used transaction management systems for mainframe-based enterprises.

We begin with the example of a travel agency with a requirement common to many mainframe customers: Provide customers with more immediate access to services and exploit the benefits of Internet-based commerce.

Example of global online processing–the new big picture

A big travel agency has relied on a mainframe-based batch system for many years. Over the years, the agency's customers have enjoyed excellent service, and the agency has continuously improved its systems.

When the business was begun, their IT staff designed some applications to support the agency's internal and external processes: Employee information, customer information, contacts with car rental companies, hotels all over the world, scheduled flights of airlines, and so on. At first, these applications were updated periodically by batch processing.

This kind of data is not static, however, and has become increasingly prone to frequent change. Because prices, for example, change frequently, it became more difficult over time to maintain current information. The agency's customers wanted their information now and that was not always possible through fixed intervals of batch updates (consider the time difference between Asia, Europe, and America).

If these workloads were to be done through traditional mainframe batch jobs, it would mean a certain time lapse between the reception of the change and the actual update. The agency needed a way to update small amounts of data provided in bits and pieces--by phone, fax, or e-mail–the instant that changes occur (Figure 1).

Figure 1. A practical example

Therefore, the agency IT staff created some new applications. Since changes need to be immediately reflected to the applications's end-users, the new applications are transactional in nature. The applications are called transaction or interactive applications because changes in the system data are effective immediately.

The travel agency contacted its suppliers to see what could be done. They needed a way to let the computers talk to each other. Some of the airlines were also working on mainframes, others were not, and everybody wanted to keep their own applications.

Eventually, they found a solution! It made communicating easy: you could just ask a question and some seconds later get the result–great stuff.

More innovations were required because the customers also evolved. The personal computer got into their homes, so they wanted to see travel possibilities through the Internet. Some customers used their mobile computers as a wireless access point (WAP).