Establishing the Registry
Vendors may have expected Internet-based registries based on the Universal Description, Discovery and Integration (UDDI) standard to spread like wildfire. But early SOA adopters care more about internal registries.
That doesn't mean UDDI is dead, though. UDDI was so important to The Hartford that it chose its registry based on the product's conformance to UDDI 3.0. (Officials declined to name the product due to a company policy against endorsing vendors.) The registry includes metadata describing the services and the means to connect to services via particular transports. But the UDDI registry isn't meant for everything. Departments continue to maintain local registries for some services they create, because The Hartford is selective about what goes into its enterprise registry.
"We don't want to create a junk drawer of services," says Moreland. "What we feel should be in the enterprise UDDI are services that will give us leverage and flexibility across the enterprise."
Providence Health System uses the Infravio management framework for its service library, and much to the surprise of company sceptics, its developers are actually reusing services, now that they can find the Web Services Description Language (WSDL) files defining the interfaces. "We commonly refer to this as 'Google-izing' Web services," says Michael Reagin, Providence Health's director of research and development. "They can reuse services with minor modifications in a couple of hours. People are more productive. Everyone's happy." Providence Health's greater concern these days is managing its growing number of Web services and SOA framework from an operational standpoint. The company has close to 50 composite services, each one comprising one to 20 more granular subservices.
Early adopters that couldn't find a registry to suit their needs built their own. Danske Bank maintains separate repositories for components from its mainframes and J2EE- and Microsoft .Net-based application servers. The repositories replicate between each other, forming one logical repository that essentially is a superset of a UDDI registry, adding operational parameters for functions such as load balancing, says CIO Peter Schleidt. A service integrator agent dynamically selects the most efficient way to call a service, using SOAP over HTTP or more efficient, proprietary protocols.
Danske also has a structured library for its services and their corresponding interfaces. The library also houses information about the relationships between its functional and process models. There's even a librarian that developers can call for help. But the library didn't launch until a year ago - "a lot later than we should have been doing that", Schleidt says.
Governance
When push comes to shove, a governance body can help a company stick to its SOA principles. Danske Bank has steering committees in 18 different business areas for product, process and IT development. But when business managers are anxious to beat the competition, they're sometimes tempted to forgo the generic SOA approach if it takes longer to complete. "You need a governance process where you can handle situations like that," says Schleidt. "We always have the time to change things afterwards, so why not try to turn it around and do it right the first time?" The quick-hit approach can have long-term consequences. Danske now has two personalization engines, four interactive customer communication services and four payment-handling applications, Torp says.
Two years ago, The Hartford formed a central group called the Property and Casualty Architects Collective to examine how it would adopt a SOA across the enterprise. The group put together a reference architecture outlining recommended approaches, practices and products to be used in a particular context. "It's about shared architectural thought and reuse of thought processes. That's where the hard work and value is," says James McGovern, an enterprise architect at The Hartford.
A separate application infrastructure delivery group is responsible for selecting and implementing the management platform, business process engine and UDDI registry, as well as making sure the WSDL files used to describe service interfaces conform to standards. An architect not involved with a particular project reviews the project's application design to make sure services aren't duplicated.
At Cendant, project managers have that responsibility. The service name and input and output fields are accessible through an XML-based layer in its Rosetta Stone business domain model. A single group is responsible for updating the business domain model. "This is how we control reuse," Wiseman says.
If a business domain owner spots a service already in the registry, the service is flagged as a candidate for reuse. A SOA governance board, largely consisting of IT managers, then takes over. Developers need not apply.
"The programmer is the last person that should make the decision," says Wiseman. "They will always want to write something new."
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