In the ’90s, gloom and doom predictions repeatedly said the mainframe was dying. These predictions were clearly way off; mainframes are far from dead, as they still host most business transactions and enterprise data.
Microsoft has wanted to get into the game for some time and has developed numerous products that ease and enhance application development. But can Microsoft, with its .NET development and server environments, provide a true value-added function to today’s complex enterprise z/systems? This article examines the mainframe’s recent “comeback.” While other viable development environments for creating mainframe-based Web Services exist, our focus is on the Microsoft-centric environment. We’ll highlight available products from several vendors and explore Microsoft’s Host Integration Server 2004 (HIS 2004) to deploy a Service-Oriented Architecture (SOA), which uses both mainframe and .NET technologies.
Setting Your Objectives
Many consider SOAs to be the source of a major change in computing. The World Wide Web Consortium (W3C) defines SOA as “a set of components that can be invoked, and whose interface descriptions can be published and discovered.” Dr. Annie Shum, corporate architect at BMC Software, has been an SOA evangelist since SOAs first emerged. Annie, like many others, goes beyond the W3C definition to tie in design and business concepts. She defines an SOA as “a set of prescriptive design principles for building composite software applications based on autonomous services with standardized interfaces to leverage reusability and interoperability—independent of protocol, platform, language, and internal data or algorithms. In a nutshell, SOA facilitates the design, deployment, management, and governance of software that mirrors business processes.”
SOA-based Web Services provide a new mindset for mainframe users and new uses for the mainframe. But Web Services alone aren’t an SOA: The former is a technology, while the latter is a set of nimble design principles and architecture blueprints. If you blindly apply SOAP and XML toolkits, you may not achieve an SOA. Worse, you can incur substantial overhead (with things such as SOAP wrappers) without gaining ground in interoperability and reuse.
So, before we take the plunge into the Microsoft .NET tank, consider that Java is a major mainframe SOA enabler - even more so than .NET. WebSphere is a prime example and IBM is making sure of that. CICS is all Java-enabled for the Web Services piece. IBM’s zSeries Application Assist Processor (zAAP) provides a specialized z/OS Java execution environment; it’s designed to attract more Java development on the mainframe for SOA. So don’t put all your eggs into the Microsoft basket, so to speak, before taking a look around!
With double-digit growth for the past two years, and five consecutive quarters of growth, IBM is enjoying a virtual monopoly on big iron. Although it appears sales may be stabilizing, this is still impressive growth in a market once thought to be declining. Why does this technology thrive even when MIPS, memory, and storage cost substantially more than those of Unix or Windows servers? Years of capital investment, incredible reliability, and astronomical switching costs are the usual reasons. But the most compelling reason is the enormous business value of mainframe applications, most written in COBOL or PL/I.
We went through the last decade with many industry watchers advising everyone to get off the mainframe. But organizations have discovered that moving host applications to Windows, Unix, or other platforms just isn’t cost-effective. Some companies saved money on hardware and software, but they spent it on administrators, and there simply weren’t huge savings to be had. The mentality now is simply to get the most from your existing assets. So, rather than retiring big iron, enterprises seem more intent than ever on disseminating the core business value. By developing SOAs 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.
The Mainframe Exposed