Opening up the mainframe

Back in 1991, InfoWorld's then Editor in Chief Stewart Alsop predicted the plug would be pulled on the last mainframe in five years.

Oops. Eight years after their forecasted demise, mainframes today host, by most estimates, the majority of business transactions and enterprise data. IBM, which now enjoys a virtual monopoly on big iron, sold $6.8 billion's worth in 2003, a year that saw sales of IBM zSeries mainframes (whose top-end models go by the nickname "T-Rex") jump 33 percent.

Why do dinosaurs thrive even when their MIPS, memory, and storage cost magnitudes more than those of Unix or Windows servers? Decades of capital investment, monumental reliability, and mind-blowing switching costs are the usual explanations. But the most compelling reason of all is mainframe applications, most written in Cobol or PL/I, have amassed enormous business value.

Brian Safron, program manager of enterprise transformation at IBM, likes to talk about the "incredible depth of business knowledge" embedded in mainframe applications.

 "When you try to reproduce [on another platform] an application that has captured 10 or 15 or even five years of business logic … you're going to go through several years of pain just to get the [new] application back up to the point where it was," Safron says.

Rather than retire big iron, enterprises seem more intent than ever on disseminating the core business value that Safron extols to a wider audience -- and a wave of new legacy integration technologies has arrived to do just that. Today, as companies draw up plans for SOAs (service-oriented architectures) that treat applications as reusable services, mainframes promise to play a central role. But the key is in selecting the right integration tools for exposing mainframe-derived services.

That selection is no easy task, according to Jake Freivald, marketing director at integration software provider iWay. "Most vendors have a particular view of things because they do a certain type of thing really well and they don't do the other things very well. And that's a real problem," Freivald warns. "People don't understand the range of options that are open to them due to vendor hype."

Going Through the Front Door

One of the least-hyped options is also the quickest and easiest to implement: deploying software that emulates a 3270 mainframe terminal and rolls mainframe apps into Web apps. The most primitive variant, where the software scrapes 3270 green screens and pops them into the browser, has been around since the mid-'90s. But new tools from companies such as WRQ and NetManage are taking this approach to a new level.

Benoit Lheureux, a Gartner research director, notes that the terminal emulation approach is mostly foolproof. "It doesn't matter how freaking old the application is," Lheureux says. "If there's a 3270 stream you can tap into it and use it for input and output." In addition, he says, it's nonintrusive: Mainframe personnel don't need to be involved in development, and all the business rules baked into the mainframe application that protect the database remain in effect. The downsides are performance limitations and "brittleness" -- if a mainframe app changes without warning, any apps that depend on the 3270 connection break.