Service-oriented architecture is an idea, not a technology. Boundless in scope, it promises both unlimited software reuse and the interconnection of everything, as long as IT is willing to wrap legacy applications in standard interfaces and construct new apps as services, the capabilities of which other software can tap into.
The idea is simple, but the execution isn’t, because SOA turns the conventional model of enterprise software development on its head. Normally, programmers write software based on a set of well-defined requirements. SOA demands that organisations create an ecosystem of services that may ultimately have an army of stakeholders inside and outside the firewall. The initial challenge of SOA is knowing where and how to start -- where to draw a box around a fixed set of requirements and how to build services that will yield tangible ROI while keeping an SOA fully extensible.
Telecom providers are competing tooth and nail to provide consumer and business customers with the latest and greatest value-added services. This smorgasbord of offerings includes everything from ring-tone downloads to hosted messaging, accounting, and other business services. An SOA makes perfect sense in this have-it-your-way environment because it enables providers to cobble together new offerings with those of third parties and integrate them quickly with their internal, mainframe-based billing, provisioning, and other support systems.
That’s exactly the approach BT wanted to take in serving its SMB broadband customers.
“SMB customers come to us for broadband access first,” says Norman Street, head of Internet applications and technology at BT Retail. “But the scenario is that as they become more savvy and the Internet becomes more integral to their business they’ll eventually start moving business processes online in an ASP model.”
The hosted scenario is especially appropriate for businesses with fewer than 100 employees because these organisations often lack sufficient support services or suffer from understaffed IT departments. “We were looking to develop some of these service offerings in-house but also bundle them with third-party applications and mobile products,” Street says.
To compete effectively, BT needed to be able to quickly test new services in the market. If a service proved profitable, it would have to scale quickly. If it didn’t, BT had to be able to decommission the service and replace it with another without a lot of integration effort. BT was also looking to allow customers to manage their own subscribed services online through a Web-based interface.
It was clear that BT’s current integration model couldn’t support such a fast-paced scenario. “We were using a typical spoke model for integrating services with our back-end systems. We really needed to reduce the time and cost of integration and become a lot more agile,” Street says.
After looking into several alternatives, BT quickly concluded that it needed an SOA. BEA Systems had supplied BT with integration technologies in the past, but for this project, BT decided to go with Microsoft’s CSF (Connected Services Framework), an SOA-based service-delivery platform that functions as an extension of Microsoft BizTalk Server, SQL Server, and Windows Server 2003.
CSF provides tools and components geared specifically to the needs of service providers looking to bundle services for a variety of devices, such as PCs, PDAs, and mobile phones, and to quickly plug them in to their back-end business and operational support systems. These include a number of adapters that hook into existing BSS (business support system) and OSS (operation support system) applications and expose them as Web services. It also includes a UDDI/WDSL service directory and tools and standards for defining quality of service, managing identities using Active Directory and Microsoft Identity Integration Server 2003, and managing other service deployment and delivery functions.
“BizTalk Server provides a workflow engine and templates to configure the business logic,” Street says. It also handles message flows and other integration functions. SQL Server holds the user and product data. And of course, it all runs on Windows 2003 server.
Although BEA provided a versatile set of tools, Street and others at BT liked the idea that Microsoft had a platform specifically targeted to service providers. “Microsoft was very conscious of the advantages of a complete platform approach,” Street says. “With CSF we got much more out of the box, which would take away some integration steps.”
BT was also aware that Microsoft had the kind of applications SMB users would be interested in. “If we were going to be selling those applications, it made sense to get the integration technology from the same source,” Street says. “At the same time, CSF had well-defined Web service interfaces and the open standards to integrate with any application.” And Street was aware that Microsoft was providing tools for and encouraging .Net developers to develop to CSF. “We felt that there would be applications from third-party .Net developers that would undoubtedly be useful for our small and medium-sized business customers,” he says.
CSF’s standard Web service interfaces would make it easy to plug in third-party applications, build composite applications, and tie it all into their back-end systems. Introducing and retiring services would mean simple changes to the CSF interface as opposed to building or unravelling multiple layers of custom integration.
Next summer BT plans to introduce its first set of hosted messaging services based on Microsoft’s Solution for Hosted Messaging and Collaboration, which provides an adapter for CSF. Future plans include bundling third-party applications, possibly migrating some of BT’s existing applications off its legacy platforms to integrate with CSF, and making BT Retail’s CSF-based services available to other parts of BT’s business. “CSF would make it relatively simple to, for example, provision a mailbox and then bundle it with a mobile service,” Street says. As usual, when an SOA is operational, there’s no shortage of ideas to expand it.