Thin Clients and Decision Support - Technology Information - Column

One of the feature articles in this issue is on thin clients, so I thought I would discuss what's happening relative to thin clients in the decision support software (DSS) arena.

There are really two kinds of thin clients to consider: the network computer (NC) and small footprint PCs. The NC boots from a server and runs Java applications that are downloaded from the server, while a thin Windows client runs a browser. With either kind, the thin client approach has a number of advantages. First, the user interface -- the browser -- is essentially fee. Second, once the browser is installed, it can run any Web-enabled application, which minimizes the work required to install, configure and maintain applications.

If an organization deploys a DSS application using traditional client/server tools, a system administrator must install the software on every PC that will run the application. This kind of overhead makes administrators reluctant to roll out a client/server application to thousands of users. Per-seat license fees can be considerable, although site licenses can keep this cost down.

Now, with the advent of Web-enabled DSS applications, thousands or even millions of clients can access an application via a Web browser, and the system administrator can focus on server administrator (performance, security, availability, and so on). Access to the server is controlled with a concurrent user licensing scheme, which simplifies license management and reduces overall costs.

However, there are some important issues to consider when you are selecting a DSS tool for a Web environment. The simplest browser-based applications use HTML. HTML has come a long way, and includes features such as frames, the ability to deploy pages with dialog boxes, and many of the features associated with forms. It's simple, it's straightforward, and it works on any browser.

However, HTML is a page-layout tool, not a programming language. If you want a sophisticated query and analysis tool with features such as drag-and-drop, table pivots, chart or graph rotation, you can't do it in HTML. The best you can do is generate and download another HTML page. This is functional, but limited to relatively static reports.

For a more interactive interface, similar to a client/server tool, there are three options. Java enables a developer to provide all the functionality associated with a client/server tool, and it runs on almost anything. However, Java has several problems. One is the it's interpretive, so it doesn't have the performance of a compiled language. Another problem is that Java applets are downloaded from a server every time they run. If the applet is large, or the network is busy, download time can become an issue. The third problem is that Java applets can't access local devices, such as disk drives or printers, which makes it difficult to save or share insights. This is not a problem, however, with Java applications.

ActiveX controls, in the form of data link libraries (DLL), can be downloaded from a server, and are self-installable. ActiveX runs only on Windows 95 and Windows NT, and can open up security holes if you're careless. Downloaded DLLs may overwrite existing DLLs, and debugging DLL conflicts is not for the faint of heart.

Browser-specific plug-ins can also be installed on a local hard drive. Your organization will need to standardize on one browser, and depending on the platform, there may be DLL conflicts or potential security breaches. The plug-in image may be fairly hefty -- 2 MB is not uncommon -- but it needs to downloaded only once.

Both ActiveX controls and plug-ins can download an update if they detect a more recent version on the server, and can install the update without user intervention. Plug-ins and ActiveX controls are compiled, which improves performance relative to Java.

If you need to deliver query and analysis functionality to a large number of users, your best alternative is to use Web technology. Examine the various tools and select the best feature/function mix for your users. If your users don't require a highly interactive power tool, use an HTML-based tool. If they need a more flexible interface, decide if you want to go with Java, which is portable but has potential performance problems, or go with ActiveX and plug-ins, which are limited to certain platforms and contain potential for internal conflicts or security breaches.

Robert Craig is director, Data Warehousing and Business Intelligence Division, at Hurwitz Group Inc. (Framingham, Mass.). Contact him at rcraig@hurwitz.com or via the Web at www.hurwitz.com.

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