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Client Access Platforms: Present and Future

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Ever since IBM shipped the first version of Client Access (back in the DOS days), one of the main objectives has been to make sure that the latest and most popular client operating systems are supported. There were the Windows 3.1 years and the OS/2 years, which eventually gave way to the 9x and NT-based operating systems. The goal of providing users iSeries access from popular client platforms is unchanged today.

This article describes what is being done to help ensure that the clients of choice can still access iSeries resources. (Naturally, IBM will drop support for some Windows operating systems that Microsoft itself no longer supports.) Throughout this article, I'll make statements regarding IBM's intentions for supporting new platforms. These statements imply no commitment from IBM that this support will be available.

A Backward Glance

The first product of the 9x/NT era was Client Access for Windows 95/NT. This client started shipping in 1995, and its last deliverable (5763-XD1, V3R2M0) was for OS/400 V4R5 systems. Initially, it supported just Windows 95, but Windows NT and 98 were added later.

Starting in V4R4, a new, enhanced Windows 32-bit client called Client Access Express for Windows (5763-XE1) was delivered, and it replaced Client Access for Windows 95/NT. In this article, I will refer to it simply as "Express." As most iSeries customers are probably aware, Express was the first Client Access product that did not provide support for SNA connections, in favor of providing optimized TCP/IP access.

SNA (APPC/APPN) Connectivity

The Windows 95/NT client support ends when V4R5 ends (currently scheduled for December 31, 2002). After that, there are no plans to support any SNA client. In addition, as of OS/400 V5R1, there are no more Client Access products that support SNA. V4R5 was the last release to support the Client Access for Windows 95/NT product. There were lots of reasons to leave SNA behind, but I won't discuss that here. Since the entire computing industry has embraced TCP/IP for connectivity, this is the present and planned direction for Client Access.

Windows Operating System Support

Released in 1999, the V4R4 version of Express could be used with Windows 95, 98, Me, and NT4.0.

Released in 2000, the V4R5 version of Express added support for Windows 2000.

Released in 2001, the V5R1 version of Express added support for Windows XP.


With the V5R1M0 version of Express, no Windows support was dropped. Windows 95, 98, Me, NT 4.0, 2000, and XP are all supported. IBM's current plan is to continue to support all of those operating systems on V5R1M0 Express until V5R1M0 Express goes out of support. This will happen when V5R1 OS/400 goes out of support, which is currently scheduled to be in May 2003 (although this is subject to change). However, as Microsoft drops supports for older versions of Windows, there may be some issues that cannot be solved on these older versions.

When V5R1M0 Express started shipping, Microsoft supported all those operating systems or planned to soon (Windows XP was released about four months after V5R1). The IBM Client Access development team tested each one. For NT 4.0 and Windows 2000, workstation and server versions were tested. Although the traditional use of Client Access has been for workstations, a growing number of customers run Express on the middle tier of a three-tier network. This may be done by installing Express on a Windows server running Terminal Services, or it may be by running Express APIs as services on a Windows server. The Microsoft Terminal Server Edition for NT 4.0 and Windows 2000 are both supported for use as terminal servers, so you can install Express once and then have multiple clients connect in to it to use Express functions. In addition, if Citrix Metaframe is installed, those attached clients don't even have to be Windows clients. Customers who need to run parts of Express as services on Windows server platforms should be aware that the Express APIs are capable of running on Windows NT and 2000 servers that are running Internet Information Services (IIS). This allows remote clients to access the iSeries database using Microsoft Active Server Pages (ASP). Also, the Express ODBC driver is supported in the Microsoft Transaction Server (MTS) environment.


The V5R2M0 version has been renamed because of the rebranding IBM has done. The new name is iSeries Access for Windows, which is now part of the iSeries Access family. All of the environments supported for V5R1 continue to be supported in V5R2, with the exception of Windows 95. Microsoft ended its extended support of Windows 95 in December 2001, so it didn't seem appropriate to come out with a new release of iSeries Access that supported it. Three other considerations led to IBM not supporting Windows 95:

  1. Installed with Express were a number of Microsoft redistributable files that were needed to ensure that all functions of Express could work on Windows 95. These files are packaged as part of the operating system in later versions of Windows (98, NT, etc.), so there is no need for Express to install them there. By not shipping these files, IBM reduces the likelihood that Express could replace another version of those files on a PC (which could have a negative effect on other applications).
  2. The TCP/IP stack in Windows 95 was built on Winsock 1.1. All later Windows versions were built on Winsock 2.0 or greater. By dropping support for Winsock 1.1, Express can now take advantage of additional functionality available only in Winsock 2.0 or greater, and it also improves performance (Note: Downloading Winsock 2.x from Microsoft's Web site may enable much of iSeries Access to work with V5R2, but IBM does not support this environment).

3. IBM could focus more testing and development on other operating systems.

Also, IBM plans to support the Windows .Net Server operating system (the replacement product for Windows 2000 Server) soon after it becomes generally available. During V5R2 development, some testing was done with beta versions of this operating system. It's likely that testing of the final version of Windows .Net Server will be done with a specific service pack level of V5R2M0 iSeries Access for Windows. Therefore, the support position will specify that a specific service pack level or greater will be required for official support. Watch the iSeries Access Web site for future information.

Future iSeries Access Releases

As I mentioned, the iSeries Access development team plans to support the operating systems that are popular with its users. So as new Microsoft versions of the business versions of Windows are released, the plan is to support them soon afterward. Microsoft press releases have alluded to a future Windows version code-named Longhorn. Since there is no way of knowing when that will actually ship, I can't guess which release of iSeries Access will support it. But the iSeries Access Web site will be updated when this is known.

Of course, in order to keep supporting new operating systems, older ones eventually have to be dropped. In the release after V5R2, the plan is to drop support of the remaining Windows 9x operating systems (98 and Me). Here are some of the reasons:

  1. According to the Microsoft Web site, Microsoft will no longer support Windows 98 after June 30, 2003.
  2. A few months after the Windows Me announcement, Microsoft announced that business applications are not supported on Windows Me (it's for home use only). Since iSeries Access for Windows is classified as a business application, continued IBM support of this product on Windows Me is not appropriate.

3. There are functions and interfaces available with the NT-based operating systems (NT, 2000, XP) that are not available on the 9x-based operating systems. Enhancements planned for the next release of iSeries Access for Windows may rely on these functions and interfaces.

Although Microsoft has stated that it doesn't plan to support Windows NT 4.0 after the summer of 2003, IBM currently plans to continue to support iSeries Access on the Windows NT 4.0 platform in the release after V5R2. A large number of customers have told IBM that they won't be able to migrate off of Windows NT 4.0 before Microsoft drops support of it.

Looking at the big picture, you can see that IBM does intend to support iSeries Access on all of the Microsoft business versions of Windows longer than Microsoft actually supports the operating systems. If a customer reports an iSeries Access problem on an operating system that Microsoft no longer supports, IBM Service will work on the problem. However, if the problem is eventually determined to be a defect in the Windows operating system, no additional assistance can be provided. iSeries Access users need to be aware of this.

Figure 1 shows a chart of the expected dates for end of support for the most recent Microsoft operating systems. Note that these dates could change. They are based on what is currently documented on the Microsoft Web site, and the currently announced dates for OS/400 release end of support.


Windows OS
Microsoft End of Extended Support
IBM iSeries Access for Windows End of Support
Windows 95
Windows 98
Windows Me
Windows NT 4.0
2005 or later
Windows 2000
No plan for end of support yet
Windows XP

Figure 1: The expected dates for end of support of these Microsoft operating systems are shown here.


Processor Support

For a number of years, the IBM iSeries Access development team has not had to worry too much about what type of processor Windows is running on. They've all been 32-bit, and compatibility has not been an issue, whether it's Intel or AMD processors that are being used. As performance of the processors increased, testing was done to help ensure that Client/iSeries Access could handle it. As multi-processor PCs arrived on the scene, tweaks were made to the product to handle those also.

However, the new 64-bit processors are a different challenge. Within the past year, Intel released Itanium, its first entry into the 64-bit arena. Itanium can run both 32- and 64-bit Windows applications, but Intel stated that there would be a significant performance degradation when running in 32-bit mode. Since the first uses of Itanium are predicted to be in servers, the IBM iSeries Access development team decided to do a 64-bit port of the most performance-critical functions of the product that are most often run on a server (usually in the middle tier of a three-tier network). Therefore, in the V5R2M0 release, both 32-bit and 64-bit versions of ODBC and OLE DB exist. Most of the remainder of the product will run in 32-bit mode on Itanium processors, but there will likely be a few restrictions. Any applications that are ported to 64-bit and require the use of ODBC will need to use the 64-bit iSeries Access for Windows ODBC driver. Official support on Itanium is planned for soon after the 64-bit version of Windows .Net Server becomes publicly available. When the follow-on to Itanium becomes available, iSeries Access will likely be tested with it also. If you have any interest in testing the 64-bit support, contact me at my email address at the end of this article.

Another 64-bit processor that is expected soon is AMD's Opteron, which was formerly code-named Sledgehammer. According to statements from AMD, this chip will not have a performance degradation when running 32-bit applications on it. IBM plans to test iSeries Access for Windows on this platform at some time.


Although most of Client/iSeries Access customers use Windows as their client operating system, the iSeries Access family does have solutions for non-Windows platforms (such as Linux, Macintosh, AIX, and OS/2). The iSeries Access for Web product started shipping in September 2001. Since it runs as servlets on an iSeries server, no code needs to be installed on the PC clients. This allows the product to run on any platform that supports a Web browser. While iSeries Access for Web does not have all of the functions that iSeries Access for Windows has, it does have most of what an end user requires, such as data transfer, 5250 emulation, control of printers and print jobs, and file system access. This product is ideal for customers who don't want to manage software installed on multiple PCs, who need to be able to access their iSeries from outside a firewall, or who have non-Windows PCs. It is not IBM's plan at this time to replace the iSeries Access for Windows product with iSeries Access for Web for a couple of reasons:

  • iSeries Access for Web is intended for casual end users, and the functionality that is available through a Web interface restricts some of the advanced capabilities our users require.
  • It is IBM's plan to provide Web access to IBM servers in a common manner for a common set of functions, which will be a subset of all management functions that are necessary. Therefore, iSeries-specific management actions are planned to be primarily anchored in iSeries Access for Windows.

If the only function a user needs for accessing an iSeries is ODBC, and use of a Linux client is desired, then there is another iSeries Access solution. The iSeries ODBC driver for Linux is now available as a Web download.

Whether iSeries database access is needed from a Linux PC or from an iSeries Linux partition, this ODBC driver should meet users' needs. Also, since it shares its source code with the iSeries Access for Windows ODBC driver, it should have the same level of function, and when fixes are made to one driver, the other will automatically get the same fix.


The iSeries Access family of products should meet users' needs for accessing iSeries servers from the platforms that they use. By testing on beta software and hardware and by always looking ahead, IBM ensures that iSeries Access will likely have a solution when it's needed. The development of the iSeries Access for Web product has positioned IBM to better meet requirements for non-Windows platforms (since only a browser is required on the client). IBM's plan to deliver iSeries access solutions on strategic business versions of the client operating systems is still intact.

Jeff Van Heuklon is currently the Technical Chief Engineering Manager for the iSeries Access family. In this role, he is responsible for iSeries Access strategy, plans, and design control. He can be reached at This email address is being protected from spambots. You need JavaScript enabled to view it..



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