Downsizing : Client/Server Computing Joe Wang, The Upjohn Company, Kalamazoo, MI (616)329-8421 ABSTRACT Client/Server "fever" is spreading across Corporate America like wild fire. Does your company want to get on the bandwagon? Can you really save money by using Client/Server technology? How much productivity can you gain when you migrate your system to the Client/Server platform? This paper gives answers to six key questions of "Downsizing". It also provides practical advises on selecting a Client/Server model which best ms your shop and your SAS applications. 1) Why do you want to downsize? 2) What is client/server? 3) What is the best Client/Network/Server Operating System? 4) Is SAS portable? 5) What are the success factors? 6) What are the potential problems? - With PC SAS - Without PC SAS WHY DO YOU WANT TO DOWNSIZE? In the past two decades, the emergence of advanced personal computers and workstations, globally connected local area networks and data communications, distributed database management software, and graphical user interfaces enable many companies to migrate their applications from a mainframe to client/server environment. There are six major reasons for downsizing. 1) Better user interface Graphical User Interface (GUI) has not only made software systems more user friendly, they have also set standards for application program interfacing. GUI provides an end user with a "point and click" type environment with pop-up menus, scroll bars, and radio buttons. Standardized interfaces for applications allow users to make quick transitions to other GUI-based applications. 2) Easy data access The Local Area Network (LAN) provides a means to connect the new generation of powerful personal workstations to other LAN, midrange, and mainframe systems. The ability to be connected to multiple platforms allows the user to transparently access data residing on different platforms. Easy-to-use 4GL tools use SOL commands as a generic means to retrieve information or statistic, more quickly, allowing us to react faster to industry changes. 3) Flexible system configuration Because of the low cost of the hardware and software of the client/server, the end user department can change/upgrade hardware and software configuration quickly based on the users' needs. 4) User has more control As technology moves processing power and applications development tools to the user department level, applications take less development time and ongoing support. End user departments have more control on the system configuration and priority of projects. Users are now able to accomplish many of the tasks and functions that previously required the intervention of programmers. 5) Cost saving Since the cost ratio of PCs and servers 1368
are dropping every year, some experts believe that client/server computing could be half as expensive as minicomputer-based systems and one-third as expensive as mainframe computing. In general, when migrating to a client/server, users save cost in tenms of host hardware, maintenance, and licensing fees. 6) Re-engineer the business process With this new enabling technology, Client/Server, business executives should be able to redesign the business process to coordinate crossfunctional workflow, infonmation technology, people and organization, policy and regulation, and physical infrastructure. The end result is to build more flexible and effective process to deliver more value to the organization's customers. While downsizing may offer more power on the desktop for less cost, most organizations still have large investments in mainframe hardware, software, and data. Many downsizing strategies do not totally eliminate traditional mainframe systems, but rather attempt to select the most appropriate platfonm or mix of platfonms for a business enterprise. WHAT IS CLIENT/SERVER? 1) Definition of Client/Server The key aspect of Client/Server computing is the capability of one or more computers (Clients) to access (via networks) and utilize one or more computers (Servers) to perform a task. (Figure 1) In short, the server provides a service to the client. For example, the clients can be 486 PCs running Windows 3.1 and the servers are SUN SPARC workstations running UNIX. The SUN SPARC workstations provide printing, file management, and program execution services. 2) Closer look There are five layers between the client and the server: Client =========================== Programming interfaces Client/Server enabling services SAS* Server Client/Server Server compubng UNIX: multi-sesslon IBM*\lMICMS. singig.oossion Client/Server core services Communications backplane formats & protocols Network transport Server Client.-riiting Figure 1 Client/Server The application programming interfaces is the layer that users see and work with. The enabling services, such as database management, workflow routing, transaction management, and document linking, enable users to build their applications. The core services provide definition, directory, and security facilities. 1369
A communication backplane deliver the content of messages between clients and servers. Examples includes remote procedure calls, X.400 electronic mail, and object request brokers. A network transport provides communications between clients and servers. TCPIIP, NovelJ s IPX, and IBM >s SNA are the most popular transport. Surround all these layers are application development tools and management tools. These tools allow users to manage their client/server project more effectively and efficiently. WHAT IS THE BEST CLIENT/NETWORK/SERVER OPERATING SYSTEM? Picking the best operating system for your company's clientlserver platform can be tough and tricky especially when you plan to move mission-crnical applications to this platform. When you pick the best operating system, you need to pick them for the client, the network, and the server. Novell Knhwear has about 60% of the Network operating system market. Knnwear 4.x provides robust messaging, distributed security and directory services, and the fastest file and print service and allows users to easily manage large enterprise networks. Nevertheless, the new MicroSoft Windows NT 3.5 bundled wnh the BackOffice provides a superb client/server support. BackOffice offers Sal Server, SNA Server, Systems Management Server, and Mail Server which based on Windows NT. More and more companies are migrating their Knnwear servers to NT servers. Unix vendors are untlying themselves wnh the Spec 1170, Common Desktop Environment, and better PC connection to stay alive. As for the best operating system for a client, there is no definne winner yet. OS/2 Warp 3 is more robust, but n only supports a subset of the Win32 API. Windows NT is secure and robust, but h demands at least 12 MB of memory. Windows 95 will run all 16- bit Windows application in a single address space, which makes h less robust than OS/2 and NT. IS SAS PORTABLE? Ves, SAS is portable among dtlferent computer platfonns. Vou can port your SAS programs from a PC to a mini or a mainframe. Nevertheless, there are two things you need to pay attention to: 1) MuHi-platfonn version compatibilny Not all versions of SAS are compatible under different operating systems. For example, SAS 608 on IBM VM/CMS is compatible only with SAS 609 on SUN Solaris. 2) Platfonn dependent system options Before you migrate your SAS programs to another computer platfonn, h is a good practice to consolidate the platfonn dependent code like FilENAME, LlBNAME, macro library, and WORK library together in one place, test the new code on the old platfonn, move the code to the new platfonn, and change all platfonn dependent code accordingly. WHAT ARE THE SUCCESS FACTORS? In order to successfully implement a client server project, certain key criteria are required as follows. 1) Upper management support and push Support from the upper management is extremely important when unforeseeable technical problems are encountered or when the implementation slows down. 2) Top priorny project,v',:- Make sure your client/server projects have top priorhy. This will guarantee the high level of support from management and participation from users. 3) Parallel processes During the implementation, keep the old 1370
environment along with the new environment for performance comparisons until the new process has stabilized. 4) Incremental release Incremental release the new programming environment in order to ease the transition. 5) Productive project team A productive project team which consists of managers, system engineers, lead analysts, and the project leader with different knowledge. WHAT ARE THE POTENTIAL PROBLEMS? 1) IBM/UNIX/DOS file formats incompatibility This might be the most difficult problem for you to solve if you are not aware of that IBM, UNIX, and DOS have different file formats/eol (End Of Line) characters. The following are scenarios which might happen: a) When uploading PC files to VM/CMS, the whole file may become one long record sometimes. b) When using the PC editor to create REXX programs, the uni-rexx interpreter on Unix may not execute these programs. c) When using the PC editor to create DOS batch programs, DOS may not execute these programs. The key to these problems is the IBM/UNIX/DOS file format incompatibility -- namely, the choice of the End Of Line (EOl) character. The PC editor allows users to specify either the Unix or DOS EOl for a file. For files with the Unix EOl, PC/FTP (the network file transfer program) assumes that the file has the DOS EOl when the file is uploaded to VM/CMS. Therefore, the Unix EOL is ignored and the file becomes one long record when it is transferred to VM/CMS. For solving scenarios 2 and 3, the trick was to specify the Unix EOL character for running uni REXX programs on Unix and the DOS EOL character for running batch programs on DOS. 2) Slow implementation Client/Server is a new concept and technology for programmers in many company. Some programmers are not familiar with Unix or PC. When key programmers are asked to migrate their applications to this new platform, some might respond with the following: a) No time to leam or migrate b) New technology is too hard to learn c) New system/technology is not robust and error-free People resist changes because they feel more comfortable in the environment they know the best and this resistance can definitely slow down the implementation. 3) Bad vendors' technical service In the client/server environment, You purchase hardware/ software products from many different vendors. When a problem arises, the in-house Information Center and Computing Service units may not know the solution. The vendors' technical service become vital to the success of the project. 4) High development/maintenance cost Unlike the mainframe environment which users can solely rely on one vendors service, the client/server environment requires users to integrate hardware/software from many vendors. Users need to have a well defined plan/schedule on training and implementation to avoid potential high development/maintenance cost. TWO CUE NT/SERVER MODELS Two client/server models are layed out below. Which model you pick is based on the type of SAS application that you run in your 1371
company. If your application is interactive oriented, pick model 1). If you can run your applications in batch mode, pick model 2). But remember that these two models require different network bandwidth, hardware power, and software license. 1) W~h PC SAS - interactive oriented This model has four major components, a) SAS OMS b) remote compute service c) data transfer service d) remote library service For the SAS users who can not live without using the Display Manager to edit programs, subm~ a portion of program to run, fsview/fsedit a data set, this is a perfect solution. Further equipped w~h SAS's remote compute, data transfer, and remote library services, users can build various types of client/server applications. Depending the size and frequency of the data transferred between a client and a server, a high bandwidth network is needed to keep a reasonable response time. A PC wnh fast CPU and large hard disk is also required ij users want to run analysis against the data resides on the hard disk. 2) W~hout PC SAS - batch oriented REFERENCES Marion, William (1994), Client/Server Strategies Rymer, John R., "Networking's silly putty", Communications Week, June 20, 1994, p.48-49 PCWEEKLABS, "Guide to Operating Systems", PCWEEK, November 14, 1994, p.125-t63 Wang, Joe, SAS Server: Client/Server Computing", Proceedings of the Ninetheenth Annual SAS Users Group International Conference SAS is a registered trademark or trademark of SAS Inst~ute Inc. in the USA and other countries. IBM and VM/CMS are registered trademarks or trademarks of Inte~tional Business Machines Corporation. indicates USA registration. Other brand and product names are registered trademarks or trademarks of their respective companies. This model has three major components, a) MS Windows program editor b) remote shell c) NFS mount For this model, a MS Windows program edftor is the focal point. Users edit programs reside on the Unix server's directories mounted to the PC as local drives. Then, users remotely subm~ the program to a Unix server for execution. They can browse SAS log and listing files from the same program ednor when the execution is done. The setup of this model will be cheaper than the first model because ~ does not requfte a high-end PC, PC SAS, and high bandwidth network. 1372