|
Overview
The iSeries Information Center can introduce you to the i5/OS Portable Application Solutions Environment (PASE)
i5/OS PASE quick facts:
- i5/OS PASE is an integrated runtime for porting selected applications from AIX and other UNIX operating systems.
- It is not an operating system or an emulated environment. i5/OS PASE applications use the processor directly.
- i5/OS PASE provides a broad subset of AIX runtime libraries.
- i5/OS PASE provides a set of shells and utilities from AIX.
- i5/OS PASE applications may be compiled on AIX, or they may be compiled and built using an AIX compiler on i5/OS.
- i5/OS PASE applications run in normal i5/OS jobs and:
- Use i5/OS file systems.
- Access DB2, or call Java and ILE programs.
- Exploit all aspects of i5/OS, like other
IBM System i and System p share common POWER processors. This hardware has the ability to use different addressing modes: addressing 64-bit tags-active for traditional 64 bit i5/OS applications; 64-bit or 32-bit tags-inactive for traditional AIX applications. PASE exploits this capability to execute AIX applications within i5/OS jobs. Since PASE applications execute directly on the hardware, applications use the processor without additional layers or overhead. Computationally intensive applications will experience equivalent performance on AIX or i5/OS uting PASE.
PASE is not an operating system. PASE is programming model for i5/OS applications. Applications and runtime libraries use the i5/OS SLIC kernel for system services. A PASE application is therefore naturally integrated with i5/OS work management, security, backup, file systems, etc.
PASE is a no-charge option to i5/OS. i5/OS PASE provides a very large subset of 32-bit and 64-bit AIX syscalls and APIs plus nearly 200 common utilities along with the Korn, Bourne, and C shells.
DB2 for i5/OS is the database built into i5/OS. i5/OS provides PASE applications with the same Call Level Interface (CLI) set of APIs for DB2 for i5/OS that is supported for ILE. Data returned from DB2 UDB iSeries is presented in ASCII format, as expected by the majority of UNIX applications. Embedded SQL is not currently available for PASE applications.
PASE applications for i5/OS can be fully integrated with other i5/OS applications, for example an ERP application built in ILE or a WebSphere application written in Java. A mix of application models (ILE, Java, PASE) can run together in a single job.
Advantages of porting to i5/OS using PASE
Customers running applications ported using PASE do not need to learn UNIX system administration. PASE applications run in jobs using standard i5/OS work management (subsystems, etc), the integrated file system with standard save/restore operations, and standard security. No special system operations are introduced by PASE, only new applications.
Leveraging existing UNIX skills of solution providers; leveraging existing i5/OS skills of IBM System i customers
Solution developers porting to i5/OS using PASE and supporting their applications will require a combination of AIX and i5/OS programming and support skills. PASE applications may be built and compiled on AIX or built and compiled on i5/OS with AIX compilers. Application developers continue to use their existing UNIX skills. i5/OS skills are also required for converting database calls, providing integration with iSeries security, and application operational interfaces (installation, start-up, shut-down, etc.).
Solution developers also require some i5/OS skills in their support teams as customers will reference i5/OS terminology instead of UNIX terminology.
Reducing time to market
Bringing an application to the IBM System i (i5/OS) market requires three phases of effort: market development, solution enablement (including porting the application) and market introduction. Market development and introduction are efforts common to all techniques of moving applications to i5/OS. PASE can improve several aspects of the solutions enablement phase. A faster port can mean a shorter time to market.
IBM offers free automated application analysis for porting to i5/OS. When using PASE for porting to i5/OS, our automated analysis represent a more complete picture than analysis for i5/OS ILE. This is because pointer size assumptions do not change from AIX to i5/OS PASE. ILE applications use either 64-bit or 128-bit pointers. Also, PASE runtimes include more flexibility in C language support compared to the full ANSI compliant support provided in ILE C. Some time savings may be achieved in the porting phase by not having to modify the application's build environment. The testing cycle for a PASE application may also be more familiar, with the same tools as on AIX.
Packaging and management
There is a second part to enablement after the application is running. All applications, whether ported in ILE or PASE require a similar amount of customization to create a product that meets iSeries customers' expectations of full integration with database, save/restore, security, ease of installation, licensing and robust support services. A product integration and test cycle is required for PASE applications to fully exploit the environment on i5/OS. The Porting Central 'tailoring' discusses the items that should be examined for an application to appeal to the IBM System i customer base.
Performance
Performance
For the latest information about PASE performance see the iSeries Performance Capabilities Reference. (The PASE information is in Chapter 21.)
Go to the iSeries Performance Management site, and follow the "Resource Library" link for the latest version of the manual.
|
