AS/400 to iSeries

AS/400 – formally renamed the “IBM iSeries,” but always known as the AS/400 – is a mid-range server designed for small businesses and businesses in large enterprises and now redesigned so that it will work well in a distributed network with s Web Application S. AS / 400 using PowerPC microprocessor technology with its reduced instruction set computer. Its operating system called OS/400. With disk storage multi-terabyte s and a Java virtual memory closely related to the operating system, IBM AS/400 hopes to make a kind of versatile all-purpose server, which can replace the PC server and web server in the world as companies compete for Wintel and UNIX servers, but give the current huge customer base immediately jump on the Internet.

The AS/400 comes with an integrated database. One option is widely installed Domino (Notes from a web browser).
According to IBM, these are some important applications for AS/400:

•     Data Warehousing: With Multi-GB of RAM, and multi-terabytes of disk space, the AS/400 can be a repository for large volumes of corporate data, including data mining could be applied.
•     Java Application Development: Java Virtual Machine with tightly integrated tools and developed by IBM to develop commercial applications with Java, the AS/400 can be used as a development system.
•     Web and e-commerce: with a Web server and applications designed to support e-business (orders, tracking orders, providing services to clients, working with partners and suppliers), and a firewall, the AS/400 can manage Internet is a medium sized company.
•     Corporate groupware services: Assuming that the Domino and Notes is part of the system, is designed to rapidly provide a company a sophisticated design e-mail, file sharing, message boards, and electronic collaboration.

Here are 4 main reasons about why use an AS/400?

•     Reliability – almost never goes down.
•     Safety – No virus known.
•     In general, a low TCO (total cost of ownership)
•     Keep your existing code (who else is running RPG?)

Programming

Programming languages available for the AS/400 include RPG, assembly language, C, C++, Pascal, Java, EGL, Perl, Smalltalk, COBOL, SQL, BASIC, PHP, PL/I, Python and REXX. Several CASE tools are available: AllFusion Plex (see *Plex Wiki), Accelerator for IBM i, ADELIA, Synon, AS/SET, IBM Rational Business Developer Extension, LANSA, ProGen Plus and GeneXus. The IBM System i fully supports the Java language, including a 32-bit Java Virtual Machine (JVM) and a 64-bit JVM.For traditional business programming languages such as RPG, COBOL, and C, the IBM System i provides an interface to the integrated database that allows these languages to treat database files much like other platforms treat ISAM or VSAM files.

Commands in the Control Language (CL) are promptable using the keyboard F4 function key, and most provide cursor-sensitive help to make specifying command parameters simpler. All command names and parameter keywords are based upon uniform standardized and mostly 3-letter abbreviations for verbs and subjects, making for easy rendering and interpretation by the application developer, as opposed to other operating systems with often cryptic or inconsistent command names for related functions or command parameter switches. For instance, the parameter keyword to apply a text description to any object to be created or changed is spelled the same way for all such commands.

Examples:

•     CRTUSRPRF - Create user profile
•     DSPUSRPRF, CHGUSRPRF, DLTUSRPRF - Display, change, and delete user profile
•     DLTLIB - Delete library
•     CRTLIB, DSPLIB, CHGLIB - Create, display, and change a library
•     ADDLIBL, CHGLIBL - Add to or change library list
•     CPYF, CRTF, DSPF, CHGF, DLTF - Copy, create, display, change, and delete file
•     WRKACTJOB - Work with Active Jobs
•     WRKSYSSTS - Work with System Status
•     STRSST, STRPASTHR, STRSBS - Start System Service Tools, start pass through (remote login), start subsystem
•     VRYCFG - Vary configuration, bring interfaces up or down
•     PWRDWNSYS - Power Down System
•     WRKSPLF - Work with spooled files

In 2000 IBM renamed the AS/400 to iSeries, as part of its e-Server branding initiative. The product line was further extended in 2004 with the introduction of the i5 servers, the first to use the IBM POWER5 processor. The architecture of the system allows for future implementation of 128-bit processors when they become available.

The AS/400 Control Language (CL) is a scripting language for the IBM AS/400 midrange platform bearing a resemblance to the IBM Job Control Language and consisting of an ever expanding set of command objects (*CMD) used to invoke traditional AS/400 programs and/or get help on what those programs do. CL can also be used to create CL programs (congruent to shell scripts) where there are additional commands that provide program-like functionality (GOTO, IF/ELSE, variable declaration, file input, etc.)

The Operating System for the AS/400 is called OS/400. The OS/400 resides above the MI. This allows the operating system to be independent from the hardware. Most operating system components handle functions such as memory, process, program, and I/O management. On the AS/400 these lower level functions are handled by the Licensed Internal Code (LIC) which is the operating system software below the MI. The LIC protects application programs and OS/400 from hardware changes. Thus again, keeping the software separate from the hardware.

Integrated File System:
The AS/400 contains an integrated file system (IFS). This means applications written on other file systems, PC, Unix, etc., can access data stored on the AS/400. The IFS integrates all file systems on the AS/400 with one interface and one set of rules. How the AS/400 developers accomplished this was to use a single root, like a PC file system, and put all other file systems under it. From a Windows client the AS/400 would appear as a network drive. Under that drive you would have PC-like subdirectories for all the file systems the AS/400 supports. Currently there is support for PC file systems, Unix file systems, OS/400 libraries, and others. The IFS provides access to the data. The data must be in compatible format for the requesting application.

The IBM AS/400 provides an integrated set of Application Development Tools (ADT) to design, develop and maintain applications. One such tool is the Programming Development Manager (PDM) that offers the following:

•     Integrated application development environment.
•     List-oriented selection of items for development or maintenance.
•     Extendable interface to tools through user-defined options.

Another tool is the Source Entry Utility (SEU) that offers a full screen editor providing syntax checking of source statements. PDM is one tool that may be used to access the SEU.