SERVICE oriented architecture in systems integration is still five years away from delivering its full potential, according to Accenture chief technology officer Don Rippert.

"The promise, which I think is realisable, is of dramatic labour savings in software projects and maintenance," he said.

"Quite a lot of effort and new skills will be required to go from what we've got today to a legitimate SOA environment. There's a pay-now-to-save-late aspect, unfortunately."

Mr Rippert said corporations were keen on SOA because it was meant to slash programming by making customisation easy.

"SOA is kind of a hybrid," he said. "It's partly packaged software and it's partly custom development, but in implementation you have a way of changing the behaviour of the software through the metadata and metalanguages that surround it, things like web services definition language, without having to change the software itself. So the promise is much less labour."

Accenture estimates another four years of work are needed before companies are "doing what the hype of SOA says with mission-critical systems", and before they are actually changing their business applications without having to touch the software.

Most companies were in the first phase of adopting SOA and using eXtensible Markup Language (XML) to use application interfaces in a more standard way, Mr Rippert said.

Phase two involved taking some business processes and turning them into web services.

"We've worked with a bank that wanted to reduce the amount of code it was maintaining from legacy systems associated with mergers," he said.

"We figured out that the process most frequently repeated across the system was a currency conversion, so we deleted that from each legacy system and created a web service to replace it."

The third phase was the introduction and full use of the enterprise service bus.

"ESBs are software products that allow you to create a business process with web services running on different platforms," Mr Rippert said.

Software companies were now making ESBs and although many people were buying them they were not using them yet.

"So phase three will be the use of ESB along with the continued use of XML and the development or purchase of software as web services," he said.

The Holy Grail won't be grasped until phase four, however.

"The generation of Business Process Execution Language is the ultimate, what everybody talks about with SOA, the ability through business processing modelling tools and BPEL to create different application behaviour without changing the software," he said.

"What they fail to mention is the phases to go through to get there."

Mr Rippert likens the present situation to the early days of client/server, when people disconnected their old character-based screens from their SNA networks and connected a PC with an emulation card instead.

"Using a technology known as a screen scraper, you could have a PC screen in colour, you could use a mouse, and everyone said they had client/server'," he said.

"It wasn't really, it was just the first little step. Five or six years later, people had multi-tier architectures, they'd replaced SNA with sockets, they were using full-blown GUIs and they had broken the monolithic mainframe apps into client/server apps.

"People are saying they have SOA right now when in fact they have XML replacing proprietary technologies from one app to another, and that's a good first step."

Mr Rippert said, however, that the SOA vision could still be derailed because it inherently relied on leading software companies sticking to the agreed SOA standards.

"The proof of the pudding will be in the eating when the final releases are sent out, but I think all of them believe the biggest impediment to selling their software is the complexity involved in using it," he said.

"Companies have hit the complexity limit. It's just too hard to buy the next release because it's too hard to make it work with all the other stuff."

IBM, Microsoft, BEA, SAP, Oracle and Sun Microsystems have substantial SOA developments under way and although there's a risk in helping to raise the tide for everybody, vendors seem willing to do it to raise the tide for themselves.

"So far, they've done an amazingly good job of sticking to the standards and we'll see whether they continue that," Mr Rippert said.

"If they do, SOA will be a big deal. If they don't, this will founder. They're all pretty desperate to remain in the main game right now, but any of them could deviate."