The iSeries and the AS/400 are major network systems distributed by IBM for relational databases. They are mid-range computers, reliable, and able to handle hundreds of users. Their integrity and security characteristics allow themto be used in "critical" applications.
RPG (Report Program Generator) is a modular programming language. Typically RPG programs are used for batch uploads on iSeries or AS/400 systems.
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 iSeries and AS/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 iSeries or AS/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 iSeries and AS/400 batch commands.
IBM's iSeries adapter uses the Access classes, and Program Call classes to call the RPG program. Data conversion classes provide the capability to convert numeric and character data between iSeries or AS/400 and Java formats.
Figure 1. Overview of AS/400 client -
server architecture
While OS/400 running on a AS/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 AS/400 system.
A diagram of the iSeries Adapter connection of the client to the server is shown below in Figure 2.