Service Oriented Architecture (SOA)

Networks and computers at the service of consumers and business is a cherished and long-held promise that has so far failed to deliver. No longer. An emerging software model supported by the European Commission and the software industry may mean that networks and computers become, finally, at your service.

Service Oriented Architecture (SOA) is a model for a new approach to information technology. "SOA is really a philosophy, a way of approaching software development around the concept of providing services," says Mike Papazoglou, author of a Web Services textbook, due out in December, and acting chair of the International Conference for Service Oriented Computing (ICSOC).

The model is a paradigm shift in software development. Instead of designing individual programmes that perform hundreds of functions, it seeks to design individual functions that can be mixed and matched to create hundreds of different services or applications.

It will have a huge impact. "Services will play a role in e-business, e-government, e-learning and I think it will have a huge impact on e-health, too," says Papazoglou. It will not only transform software development, it will ultimately enable the creation of thousands of as-yet-unimagined services.

The model requires lightweight services that are re-useable, can interoperate with each other on any platform, whether it’s a network, a workstation or a mobile phone. So, a service could be designed to check inventory, while another orders new stock and a third processes orders. All of these are small, simple pieces of software doing one function well.

But they can also be easily combined. So the sales force could enter orders into mobile phones. The mobile service alerts the inventory service, which discovers the product is not in stock and alerts the order service. The order service asks for new stock from a preferred supplier, but is told there is none, so the supplier service orders new stock from the manufacturer.

Mix and match elements to create totally new services
The potential is limited only by imagination. Already there are many impressive examples of small pieces of software combining to provide powerful, value-added services. One example combines a map service with a classified advertising service to automatically provide maps for available home rentals or purchases. Another alerts booksellers about the lowest retail price for specific books. Still others personalise advertising to a particular geographical location.

Ultimately designers will mix and match different elements to create totally new services. "Software engineering will become service engineering," says Papazoglou.

There are four fundamental elements that are key to developing the SOA concept: describe, publish, invoke and combine. "People need to be able to identify services through their description, and services must be published so they can be found. Then they need to be invoked to execute their function. Finally, they must be able to be combined with other services to provide the overall function," says Papazoglou.

Currently, work is underway to develop services around the SOA concept in many top European and US software companies. Some of the biggest are completely re-engineering their product line along SOA principles.

source: IST Results