Where do you turn for AS/400 access for UNIX clients? This article describes the history, product development, features, and architecture of a not-so-distant relative of the Client Access product family: Client Access for UNIX OS. If youre running UNIX desktops, this is definitely a product you need.
Some detractors call the AS/400 a closed system, but is that really accurate? More than with any other system, the designers of the AS/400 recognized the important roles that peer and client systems would play in current IT environments. Indeed, client/server, Web- based, and Java applications have all found their way to the AS/400 with little difficulty.
Another reason the AS/400 is so popular today is the introduction and evolution of IBMs now ubiquitous Client Access product family. In this article, I examine where Client Access for UNIX OS fits into AS/400 and UNIX shops around the world. I also look at the history of the product, its development and support structure, its features, and areas in which it can be improved in the future. This article provides you with everything you need to know to integrate your UNIX workstations with your AS/400s.
A Little History Goes a Long Way
In the beginning, there was PC Support, and it was good (for DOS-based PCs, that is). PC Support was the original suite of products made for connecting PC workstations to the AS/400. But what about other operating systems, such as UNIX and Macintosh? For shops with UNIX desktops, you had to use a product called Connection Program/400. This meant that, in a mixed environment of UNIX systems, PCs, and AS/400s, you had to purchase two different connectivity products. Moreover, if you wanted to add Macintosh to the mix, it became complicated, expensive, and quite ugly.
The fact is, all systems that need AS/400 access share the same requirements. The first of these is application access. In most cases (although this is changing somewhat), this means 5250 terminal emulation. Once your remote location has application access, you need to be able to print from your applications. Consequently, systems also need printer access, which necessitates print spooling. Inevitably, users then need file access on each
system, so shared disk space and file transfer options become key. Finally, direct data access at the record level completes the basic interoperability requirements between two systems.
Because of these requirements, PC Support evolved into Client Access. Client Access supported UNIX clients, and Connection Program/400 went to dwell in the land of the no longer supported. However, those who started using Client Access for UNIX OS soon discovered something interesting. The product is sold and supported by StarQuest Software, Inc. (www.starquest.com), a connectivity solutions developer based in Berkeley, California. It was not sold by IBM. How did StarQuest suddenly appear in this picture?
Prior to the incarnation of StarQuest Software, its founders and engineers were the principles at Loral Orion Network Systems, Inc. a supplier of SNA software for UNIX vendors. StarQuest was the leading vendor of UNIX-to-AS/400 connectivity products in the early 1990s, offering support for all major UNIX flavors. Because of its UNIX experience, StarQuest was the natural choice to develop Client Access for UNIX OS jointly with IBM. Currently, StarQuest markets Client Access for UNIX OS and also provides support and maintenance for the product.
That IBM consolidated support for UNIX, PC, and Macintosh clients into the Client Access family is a breath of fresh air for IBM customers. Instead of opting for extra charges for each client, IBM has provided its customers with a single common interface for all its clients. In addition, instead of crushing the competition, it has actually partnered with qualified vendors to improve client services. This approach is quite different in style when compared with other software giants.
Client Access for UNIX OS Features
The first thing to understand about Client Access for UNIX OS is that it is a part of the extended Client Access family; it has most of the same functionality that PC users have enjoyed for years. The second thing to understand is that Client Access for UNIX OS is based on the same AS/400 extended service libraries and shares the same code with these libraries.
Client Access for UNIX OS provides application access through standard 5250 terminal emulation. 5250 terminal emulation is one of the main features that companies use for AS/400 data access from UNIX workstations. Because UNIX terminals can be ASCII devices, X-Windows, or system console devices that support both, terminal emulation comes in both Motif and UNIX curses implementations. Client Access for UNIX OS supports X-Windows emulation packages, ASCII terminals, and various UNIX terminal emulators that connect through Telnet protocols. The product provides an easy-to-use interface for mapping keyboards and soft keys for ASCII and Motif users, so users are never stuck without access to a vital key. The terminal emulator also supports multiple sessions, text assists, and multibyte character sets for East Asian languages.
Users can transfer a file without fear of losing something in the translation. Bidirectional file transfer enables UNIX users to transfer text, binary, and source physical data files to and from AS/400 systems. Client Access for UNIX OS supports both GUI and command line processing of file transfers as well as all AS/400 field types, including packed binary or signed numeric types. ASCII-to-EBCDIC translation is optional. In addition, the product allows for binary transfers, so files can move across the network untouched with their binary integrity intact.
Client Access for UNIX OS provides access to the AS/400 command interface in several ways. Remote command enables UNIX users to execute AS/400 commands. When invoked from an application program, the remote command facility automatically retrieves data from the specified server while the application program continues to run. Client Access for UNIX OS also provides access to AS/400 data queues, which enable programmers to
write cooperative processes on UNIX and AS/400 systems that communicate asynchronously through a standard, nonprogrammatic interface.
Direct data access is one of the most powerful features of Client Access for UNIX OS. Direct data access enables UNIX programmers to access AS/400 record-level data directly for query or update and provides a useful method for integrating heterogeneous databases. The programming interface for direct data access is the key to accessing operational data on AS/400 systems from UNIX-based Web servers.
Double-byte character set support (DBCS) is provided for X-Windows, Motif, and character-based terminals that support Japanese, Korean, Traditional Chinese, and Simplified Chinese. Text, messages, and menu options and commands may be displayed in DBCS languages. Users can transfer text, binary, database, and source physical files containing double-byte data in either direction between AS/400 and UNIX systems.
Client Access for UNIX OS provides user interfaces as well as APIs for its features (sorry, no APIs are available for terminal emulation). Access to the AS/400 is provided quickly and easily from menus, the UNIX command line, or custom applications.
Specifications and Architecture
Client Access for UNIX OS could be improved in a couple of key areas. First, the services provided for client access are not symmetric. Presently, the commands can be accessed only from UNIX systems, so you cannot push a file from the AS/400 to UNIX or enter UNIX commands from the AS/400. Second, printer support should be enhanced. Users currently use native UNIX support for Line Printer Requester (LPR) or Line Printer Daemon (LPD) protocols. It works, but a faster solution could be developed. Finally, some Java access would be nice. Having Java-callable APIs would allow users to write applications in Java that access AS/400 data, giving them more options.
Client Access for UNIX OS is available for IBM AIX, Sun Solaris, HP-UX, SGI IRIX, and SCO OpenServer. Setup is fast and simple. The minimum requirements are OS/400 V3R1 or above with TCP/IP running on your AS/400. Because all AS/400 systems now come
out of the box with this level of support, the installation tasks are relegated to the UNIX system.
On UNIX systems, the product is loaded from CD-ROM. Setup involves the configuration of several user environment variables that are used primarily for operating the Client Access for UNIX OS features from user interfaces. The entire process takes about 10 minutes to complete. Client Access for UNIX OS uses the UNIX vendors installation procedure. This provides two distinct advantages: ease of use (system administrators are already familiar with the procedure) and minimal maintenance.
For interoperability between AS/400 and UNIX systems, all roads lead to Client Access for UNIX OS. Through its partnership with StarQuest Software, IBM has provided its users with the tools they need to access their AS/400 databases from UNIX workstations simply and efficiently. As one of my customers told me, Were very pleased with the product. You dont even know its there. When it comes to software, thats quite a compliment.