An overview of the OS/400 system

The IBM eServer iSeries system is a highly integrated, reliable server platform that allows businesses to run multiple operating environments simultaneously. Their integrity and security characteristics allow them to be used in many critical applications. They are mid-range computers, reliable, and able to handle hundreds of users.

Host servers handle requests from client PCs or other devices running an application as illustrated in Figure 1 to enable printing a document and other tasks. The OS/400 computers are full function servers capable of performing many tasks at once, including file, database, applications, mail, print, multimedia, fax and wireless communications. Each task server runs as a separate job on the system, and each server job sends and receives data streams on a socket connection.

One of these host servers is the Remote Command and Distributed program call server. This server handles running the programs on an OS/400 system.

IBM's Toolbox for JAVA has a multitude of packages which handle different functionalities. For example Access classes manage sign-on information, create and maintain socket connections, send and receive data, while Command Call classes run OS/400 batch commands.

IBM's iSeries adapter uses the Access classes, and Program Call classes to call the ILE program. Data conversion classes provide the capability to convert numeric and character data between OS/400 and Java formats.

Figure 1. Overview of OS/400 client - server architecture

OS/400nt - server architecture

While OS/400 is capable of handling many types of tasks, the iSeries adapter only uses the Remote Command and Distributed program call server. This server handles running the programs on the OS/400 system.

A diagram of the iSeries Adapter connection of the client to the server is shown below in Figure 2.

Figure 2. Diagram of the iSeries adapter's connections.


Copyright IBM Corp. 2004