What is it?
Middleware is software that acts as a translator between different programs, allowing them to "talk" to each other.
In February, IBM chairman Lou Gerstner declared that the first phase of the e-business era was over. From now on, he said, we will see a rise in the strategic importance of integration and infrastructure, using robust middleware. Floundering dotcoms might respond that the shortcomings of their infrastructures are the least of their problems, but then IBM is staking a lot on its middleware.
For IBM, middleware has moved on from obscure bits of plumbing and glue to embrace flagship products such as Websphere, Tivoli, Lotus Domino and DB2. More generally, middleware encompasses some of the most dynamic areas of the software market, including application servers, portals, messaging products such as MQSeries, and enterprise application integration (EAI) tools.
Where did it originate?
The term "middleware" was coined in the early 1990s to describe various approaches to linking disparate systems at the data and process level. Some of these products, for example, IBM's Cics (Customer Information Control System), had existed for decades, others were new.
Analyst firm Ovum, in the first major report on the topic, defined middleware as "off-the-shelf connectivity software that supports distributed processing at runtime, and is used by developers to build distributed software".
Ovum now says that as middleware becomes more multi-functional - with messaging and enterprise integration products coming closer together, for example - the old distinction between different categories of middleware is increasingly redundant.
What is it for?
Middleware acts as what Gartner Group calls an "enterprise nervous system", that enables data and business processes to flow through all the systems that a business and its customers and partners use.
What makes it special?
The focus has moved from joining up a company's internal systems to enabling e-business. Ideally, standards-based middleware will carry out all the integration, translation and routing needed for systems of all kinds to talk to one another.
Where is it used?
Wherever heterogeneous systems need to work together.
What does it run on?
Major suppliers include IBM, BEA (WebLogic), Iona, Microsoft, Sybase, TibCo, SeeBeyond and Candle. The Oracle 9i application server is middleware, as are Object Request Brokers.
Not to be confused with
Middle management, muddling through.
How difficult is it?
Most middleware suppliers claim that their products will work "straight out of the box", but in practice this means that APIs (application programming interfaces) between leading applications have been included. Anything beyond this basic set will require integration work, and most products come with toolsets to carry this out.
Few people know that
Outdoor activity suppliers describe shirts and trousers - the clothes between your thermal underwear and your anorak - as middle-wear.
What's coming up?
Gartner Group says emerging standards for Web services, such as Soap (Simple Object Access Protocol) and UDDI (Universal Description, Discovery and Integration), will help reduce the complexity of middleware.
Most training is provided by middleware suppliers, although there are generic courses for EAI (enterprise application integration) and messaging. For example, Learning Tree (0800-282353; www.learningtree.com) has a course that covers distributed object middleware and intranets as middleware.
Try also the Middleware Resource Center ( www.middleware.org), which gives a lot of detail on message-oriented middleware, object-oriented middleware, transaction processing middleware, database middleware and RPC (Remote Procedure Call) middleware.
Rates of pay
EAI, messaging and application server skills are all in great demand, with at least £30,000 on offer. For middleware specialists capable of tying corporate architectures together, salaries can run to £50,000-£70,000, although you could earn far more as a freelance consultant.