Everything that has happened on the Web until recently is nothing more than fun and games. The real usefulness of Web technology is about to reveal itself.

What's the real Web all about? Simple: Running businesses far more cost effectively, competing better, and making money.

The high-tech press has speculated for months on whether anyone other than pornographers has yet come up with a successful business model. But enterprises from Silicon Valley to Singapore are discovering that lowered system costs and improved market response times are available by using intranets and Web browsers to access their data center-based business systems.

Legacy Systems

What's a legacy system? According to the Free On-Line Dictionary of Computing (wombat.doc.ic.ac.uk), it's "A computer system or application program which continues to be used because of the prohibitive cost of replacing or redesigning it and despite its poor competitiveness and compatibility with modern equivalents. The implication is that the system is large, monolithic, and difficult to modify."

Some might quibble over the phrase "poor competitiveness," but there's no disputing that legacy systems are mature, often large and monolithic, and that many were designed in the era when data was stored on tapes and processed solely on a mainframe.

But the word legacy is imprecise. To some the term is just a shorthand reference to a system that runs on a mainframe; to others, it is any proprietary or customized business system that doesn't live entirely in a desktop PC.

When it comes to data, legacy encompasses two different kinds of storage: large relational database systems from vendors such as IBM, Informix, Oracle, and Sybase on the one hand, and the older, flat file databases characteristic of mainframes on the other.

Client-Server Migration

In the universe of Internet practitioners, where a RISC-based Unix box represents heavy-duty horsepower, mainframes are old technology. But big iron still is central to business operations: 70 percent of all business data resides on those platforms.

Providing efficient access to that data for front line workers has been one of the key challenges facing IT departments. Client-server is one answer, of course. But client-server is expensive to implement, involves complex database migrations, and requires substantial client-side software, training, and support.

Two recent waves of technology developments have changed the way the industry thinks about platform integration, in different ways. One, of course, is the groupware phenomenon. The second is today's cutting edge technology: using intranets to access legacy data and applications via Web browsers and similar thin clients.

Information Anywhere

Among the appealing aspects of corporate intranets are the attractiveness of the Web as an application development platform and the flexibility of the browser as a desktop client.

In general, corporate IS likes intranet-based access to business systems because deployment is simple: Load the application or gateway code on a server, publish the URL, establish authentication procedures as needed, and you're up and running. Version control isn't a problem, and updates are done once, at the server or host, rather than at each desktop. And remote access is a snap, even over dial-up and other low-bandwidth connections.

The browser has rapidly become a universal component of business desktop computers. It's a cross platform environment. It places a relatively small demand on system resources. It uses TCP/IP rather than a proprietary network protocol. And browser licenses are available either for free (Internet Explorer) or for $40 or less per copy (Navigator). It's a sharp contrast to application-specific clients.

Two Different Models

One of the issues that has delayed the migration of legacy access to the Web is the seeming disconnect between the Web's publishing model and the workflow or transaction orientation of most business software. HTML is static; it's document rather than transaction oriented. In addition, Web protocols are stateless-- every server interaction is independent of all other interactions, so there's no notion of persistence. That makes it much more difficult to craft situations in which the server can treat multipart, multipage transactions as a single unit-- something client- server application developers take for granted.

Schematically, the way to provide browser access to legacy data and transactions is to use the browser as a container for code that will emulate a front end--a query screen, a 3270 terminal, or a GUI--and load on the server a middleware or gateway tool that will convert the client input into the appropriate query form or application instructions, and do the same for the legacy system's response.

In some cases, emulating the traditional 3270 or 5250 "dumb terminal" is all that is needed to open up a legacy environment. The growing importance of legacy access is underscored by the inclusion of Netscape IBM 3270 Host On-Demand -- which uses Java to emulate a 3270 terminal in the browser environment--in Netscape Communicator.

Host-Browser or Client-Server?

Vendors have taken different approaches to green screen emulation. The simplest uses HTML code on the browser to emulate a terminal screen. Components on the server--typically run as a CGI script--strip and process user input, translate it, submit it for transmission to the host, and format the database information into returned HTML pages.

Simware of Ottawa in its Salvo Connect 2.0, for example, uses native HTML to display terminal characters, with a server-resident Information Request Broker doing the data conversion on the fly. Attachmate Emissary HostSurfer, a component of its Emissary Host Publishing System 2.0, provides HTML display of host terminals as well.

OC://WebConnect from OpenConnect Systems uses a downloaded 35KB Java applet to generate a character-based terminal emulator within the browser. At the server, data from the host is translated between an SNA-compliant data stream and the TCP/IP flow to the browser.

Some question whether anything more than green screen emulation is needed, at least for right now. Harry Fenik, vice president of the Internet consultancy Zona Research of Redwood City, CA, says, "I think the notion of deploying 3270 terminal emulation in a browser as base-level access for existing mainframe applications is a really good one. It requires almost no training, requires no mainframe work, requires no new intermediary tools."

David Johnson, senior product marketing manager for OpenConnect Systems in Dallas, notes, "The majority of the people using mainframes today have been trained on the character interface and want that interface."

But if you want a GUI front end for your existing legacy system--if icons and drag-and-drop capability will save the user significant numbers of hours or the company substantial dollars--then it can be done, using ActiveX controls or Java. True, the client won't be as thin as a pure HTML browser, but it'll still come up on the light side of the balance compared to a traditional client.

The OpenConnect OpenVista Java development environment, for example, allows development of Java-based screens, buttons, input, and output fields that connect on the server to any SNA gateway. Attachmate Emissary Host Publishing System allows you to build client-server applications in Visual Basic, then use an ActiveX control to translate the client face of the application to HTML.

The Other Side of the Browser Wars

Ever since it rolled out BackOffice, Microsoft has been seeking to penetrate the large enterprise marketplace. In the realm of legacy access, its key offerings are the Internet Information Server and its new Web application development tool, Visual InterDev. In this environment, Web page interactivity is provided by ActiveX Server Components that run on the server rather than the browser, that are then stripped out before the resulting HTML is sent to the browser.

These Active Server Pages, says Greg Leake, product manager for Visual InterDev, provide state management across users, applications, and even servers. And any existing client front end to a legacy system can be converted into ActiveX controls that can be called from a Web page.

"If you have applications for which you can create some type of interface," says Leake, "you can then create an Active Server component. Even in the case of apps that weren't originally written to have public interfaces, it's much simpler to add some modest amount of code to provide interfaces than to scrap all the business logic that's already running on that system."

Netscape's Web application development environment is Open Network Environment (ONE). It's based on HTML, of course, and on Java rather than ActiveX. Where objects in the Microsoft environment are Component Object Model (COM)-compliant and distributed messaging is handled with Distributed Component Object Model (DCOM), Netscape's strategy is based on the Internet Inter-ORB Protocol (IIOP), an open standard that's part of the Object Management Group's Common Object Request Broker Architecture (CORBA).

Netscape ONE is supported on the server side by SuiteSpot, which includes Enterprise Server 3.0.

Both Microsoft and Netscape are pushing hard to place their Web servers at the center of the enterprise. But the data they access most easily is stored in SQL databases, while the richest source of legacy data remains in mainframe systems. And access to old-style mainframe databases is slow in coming.

And Then There's IBM

On the other side of the converging technology spectrum that runs from the desktop to big iron is the prototypical mainframe company, IBM.

IBM's MQSeries is middleware designed to support workflow applications by passing messages between heterogeneous environments. It was designed to support large financial industry customers, and so offers message logging to ensure that queued messages are sent and sent only once, regardless of system malfunctions.

MQ has now grown in functionality into a message-driven infrastructure that provides a common interface for desktop access to legacy apps. "Enterprises said, 'We want one interface for new applications that we can get to from anywhere,'" reports Rob Drew, the MQSeries architect. "And they like this messaging paradigm: Put messages in a queue, and I'll process them and put my replies in a queue--I don't care where the messages came from or where they're going."

The origin and destination point for messages can now be a Web server as well. Adding intranet access requires no new coding or "protocol games," as Drew puts it. In fact, MQSeries recently added a Java client that can be downloaded into a browser as part of an HTML response; the client will then access MQ directly. And late last year, IBM joined with Sun Microsystems and Planetworks to market Planetworks Interspace, a set of development toolkits for extending access to MQSeries (and, of equal importance, IBM CICS transaction servers) from PowerBuilder, Visual Basic or ActiveX, and Java components.

IBM is also working with vendors such as Client Server Technologies and Segull Business Software b.v. who provide Java-based thin client solutions for Web- based emulation.

Enterprise Alternatives

When Lotus Development was acquired by IBM, the enterprise groupware market leader became a division of the company whose name is synonymous with big iron. It's thus hardly surprising that Lotus Notes now sports not only a browser front end but also increasingly robust hooks into legacy data.

On the front end, Lotus' Web application server, Domino, functions as a full-featured Web server that offers the added Notes functionalities of a robust object database orientation, multilevel security, and universal two-way database replication. On the back end, Domino can access databases via ODBC and its own LSXs, or LotusScript extensions, for PeopleSoft and SAP systems; DB2 extensions are planned. Another LSX interfaces with MQSeries to allow automatic transfers of legacy data to and from Lotus data fields, and CICS Link passes requests back and forth between Domino and a CICS server.

But the approach to providing intranet access to legacy systems that is likely to be most startling for the Web-centric is to skip the middleware entirely; just use the mainframe as a Web server. A two-tier setup--browser to mainframe- based Web server--sure beats for simplicity and lower cost an architecture that runs from browser to gateway to Web server to application server to mainframe.

The Issues

While cost and return on investment figures are not yet available, there is near universal agreement that a shift to thin-client browsers and server-based middleware will result in significant cost savings.

Intranet technology also makes it possible for companies to streamline and even to reinvent their business processes to compete more effectively.

"We're definitely seeing a move away from fat clients," says Drew. "People like the idea of a thin client; if it's a Web browser, so much the better."

But it's worth bearing in mind that enterprise computing, which has lots more to do with a company's profitability and competitiveness than with how new its technology is, moves far more slowly than the bleeding edge of the Web. Still, 1997 is well on its way to being the year that Web/legacy integration will come of age.

Alan S. Kay covers business technology from Washington, D.C. and San Francisco. He can be reached at ask@well.com.

Source: ZD Internet Magazine