10 Jan 1997

Distributed Applications and the Web

For two decades, the user of a corporate information system sat at an IBM "3270" display terminal (or a PC emulating one). Requests flowed through an IBM SNA network to a mainframe. Requests were handled by a Transaction Processing system with information stored in a corporate database.

As Personal Computers appeared on every desktop, information system designers searched for a way to utilize the processing power and powerful user interface that they provided. At first there was a surge of interest in "Client-Server" computing, a general term that seemed to cover several hundred different ideas. Vendors had difficulty coordinating releases of Windows 3.x, Windows 95/NT, Macintosh, and OS/2 client software. IS managers had problems distributing and maintaining this software.

Then the Web provided a different, yet curiously familiar alternative. Browsers, and portable languages like Java, provide a common interface to clients on any desktop system. Applications can be stored at a central site and distributed through the network on demand. Those who do not really need a PC can use a "thin client" on a simpler, less expensive Network Computer. Users are familiar with the Web, so they require less training. The real attraction of this design, is that it reproduces the original central corporate network design, just replacing Browsers for terminals and changing the network protocol.

Before the Web can make a transition from the distribution of advertising copy to a serious business transaction processing system, people must learn how to develop applications. Vendors have released a large number of isolated development products, but there is generally accepted strategy. This article will present a survey of the problem and many proposed solutions.

Different vendor strategies arise from deep philosophical, almost religious differences. The major players are:

Netscape (advocate of cross-platform development based on open "Standards")
Microsoft (centered on Word, Excel, and the rest of the Office suite, giving each an Internet connection)
Sun (views Java as the solution to everything, including Network Computers, interactive TV, )
Oracle (if you put enough logic in the stored procedures of the database, you only need a very thin client)

There are some areas of broad consensus, but they are buried in the details. A review of the topics will clear things up"

Prototypes of the Web - Current Web standards evolved from the success and failure of previous products.

HTTP - the Browser sends requests in the form of a text file. The Server sends a reply also as simple text.

Helpers and Plug-In's - The Netscape browser can be extended with third-party programs.

HTML Forms - Application data entry using only basic Web protocols.

CGI - The universal linkage from a Web Server to an external application program.

NSAPI - Allows applications to run on the server at high performance, if you can solve the cross-system design problems.

Browser JavaScript and VB Script - lightweight programming languages that can be embedded in a Web and run on the Browser to validate or provide extra logic for HTML fields.

LiveWire and Active Server Pages (ASP) - Server programming environments designed by Netscape and Microsoft to make Web application programming as simple as possible

Java - The hot new language everyone is talking about.

PCLT

Copyright 1996 PC Lube and Tune -- Distributed Applications and the Web H. Gilbert