December 18, 2000, 7:31 AM — Opening up your SNA or other legacy applications to the Web is a little like losing your baby teeth: It will be a little painful at first, but it's becoming a rite of passage for many enterprise networks.
Plenty of companies are going through this application extension process these days, buying into the conventional wisdom that IP-based networks are more open and less expensive to operate than older networks, such as those based on IBM's SNA. At the same time, companies that have already made big SNA investments can't just get rid of their precious applications and data without a major code rewrite.
To strike a happy medium, many users are phasing out their legacy networks but are keeping the applications and making them accessible via PCs outfitted with Web browsers. Indeed, market research firm International Data Corp. estimates that by 2002 there will 24.5 million browsers handling Web-to-host sessions, up from 2.3 million today.
However, before a Web-to-host system is launched, there are a number of things to consider: Will the applications be accessible to remote users, local users or both? Does the end user need just a basic 3270 green screen terminal emulation or a sophisticated graphical interface? Is there more than one host to access?
Choices to make
Most Web-to-host systems involve a user logging on to a Web server that downloads a Java applet to the client. The applet in turn connects to the appropriate host and the session is established. There are variations on this -- for instance, direct
There are a dozen or more Web-to-host product vendors in the market, ranging from IBM and its SecureWay Host On-Demand product, to mid-size companies, such as OpenConnect and Eicon, to start-ups, such as Ericom and Anota.
"The number of tools out there is mindboggling," says Pete Longden, Internet consultant at CareFirst BlueCross BlueShield, an Owings Mills, Md., health care provider. "Be sure you know what your requirements are and what you expect from the tool."
Longden says Web-to-host designers must have a thorough understanding of the underlying legacy network and application architectures, such as IBM's Customer Information Control System (CICS), that they are looking to link to the Web. CICS is IBM's customizable multipurpose transaction monitor.
Among the different Web-to-host offerings are IBM's tn3270 and tn5250 products, which allow SNA users on an IP net to retrieve data from a mainframe or AS/400, respectively. There are other tools for special types of access, such as Cisco's Transaction Connection software, which allows users to connect directly to DB2 and CICS applications and data on a mainframe through a Cisco router.