AS/400, iSeries, i5
i as Integration
On 2000 IBM reorganized its servers in a new brand,
server,
with 4 product's lines:
iSeries (formerly AS/400), pSeries (RS/6000), zSeries (System/390) and xSeries (Netfinity).
On May 2004 IBM announced the new eServers i5 and the OS/400 was renamed i5/OS: are these only new names, or an important evolution of 'the best computer every built' (See The iSeries corner)?
In an article published on September 2003 (What is an iSeries? - iSeries NEWS) Frank Soltis, iSeries's chief architect, wondered what makes it unique among servers:
'... the iSeries is not defined by its hardware. That hardware can in the future change completely,
and we will still have an iSeries.
... the iSeries is not defined by its operating system. If we were to change the operating system of the iSeries completely, it would still be an iSeries.
The one thing that makes an iSeries an iSeries is OS/400...
OS/400, on the other hand, is unique to the iSeries. It is OS/400 that provides the control environment and the application environment that make the iSeries something very special. It is not the simple operating system that its name implies.'
The OS/400 was created on the IBM System/38 and was named CPF (Control Program Facility): it was not an operating system in the textbook sense,
because it ' included the world's first commercially available relational database, functions to manage work in the system, a new control language, data definition interfaces,
extensive security and authorization facilities, and some powerful program development tools.
... the iSeries is not defined by its operating system. If we were to change the operating system of the iSeries completely, it would still be an iSeries.
The one thing that makes an iSeries an iSeries is OS/400...
OS/400, on the other hand, is unique to the iSeries. It is OS/400 that provides the control environment and the application environment that make the iSeries something very special. It is not the simple operating system that its name implies.'
Since the beginning the iSeries has been characterized by a native environment closely integrated: the operating system, database and development languages are all designed from the ground up to work together. During its long life, the iSeries has moved from proprietary to an open system, and now it provides advanced support for Linux, Apache, Lotus Domino, Java, NT, PHP, among others.
This evolution was made possible by some key decisions made from the S/38 designers, such as:
- The software independence from the hardware, thank to which the application lifecycle isn't hardware-driven, but requirement-driven;
- To make the MI (Machine Interface) an object-based ISA: the MI predates Java and other modern virtual machine implementations by about 20 years;
- A complete virtual system: all aspects of processing, memory, and I/O are virtual. According to Frank Soltis (Everything Virtual - iSeries NEWS January 2005), "Thanks to its virtual system design, which originated with the S/38, today's iSeries and the i5/OS operating system can live virtually forever."
Today an i5, thank to its hardware architecture POWER5, can support at the same time several platforms and operating systems sharing the database.
The transition from the traditional AS/400's development tools to the Web/Java environment can be very hard for a developer used to work with PDM e DB2 and other tools supplied 'ready for use': in the new environment more languages and tools are available, and the selection may be problematic.
Internet provide very much technical informations, but a beginner may easily waste very much time looking for the right way.
This site started as notepad, a list of useful links I found on the Web, looking for technical informations to enhance my skill.
I found very valuable the Open source community's work; believing that the free circulation of ideas is very important to improve the software development, I decided to share this experience with other developers.
