SOA too slow for the enterprise?
Connecting state and local government leaders
A few weeks back, when we were writing up our story on service-oriented architecture, one of the concerns we heard was that of scalability and system performance. Being as that so few agencies have implemented a loosely coupled architecture as of yet (though some are moving in that direction), the concern seemed nebulous. Nonetheless, performance may be something to ponder as SOA plans are brandied about.
The concern we've heard is this: Given the number of different components that could make up a service, the possibility of them working together in expedient harmony may be rather optimistic. As Dennis Nadler, chief technology officer for federal integrator Merlin Technical Solutions of Greenwood Village, Colo., told us, you don't want a Web service between you and your rocket launcher.
A few months back, Grady Booch, co-developer of the Unified Modeling Language and now Chief Scientist of IBM Rational spoke in D.C. As one of the world's leading experts in software and system architecture, he had a few words to say about SOA and Web services.
Web services 'are best suited'and this is a gross generalization'for dealing with relatively large-grained, low-frequency interactions, as opposed to high-grain, high-frequency interactions,' he said. The act of calling up a service for every transaction could be kind of burdensome when submillisecond transaction times are required.
Nonetheless, the SOA advocates we spoke with insisted performance would not be a problem with Web services writ large, for a number of different reasons.
John DeVadoss, who leads the architecture strategy team for Microsoft Corp., noted that a componentized approach could actually speed services, as the burden of executing tasks doesn't fall on a single machine. David Vap, vice president of business integration solutions for Software AG, pointed out that the steady march of ever-faster processors will all but assure this year's sluggish service will be rendered peppier with newer equipment.
Taking a wider view, George Alber, Software AG's director of federal markets and technologies, noted that comparing Web Services-based applications and non-Web Services-based applications is very much like comparing apples and oranges. He predicted that most Web services-based applications would be built solely to fill those needs that could not be fulfilled by standalone applications.
Not that Software AG admits sluggishness. When I pressed for numbers, a company representative sent over the results of a study stating that Software AG's Service Orchestrator (the software that coordinates service executions) could process a few million messages a day. The performance indeed dipped as the number of concurrent processes and complexity of messages increased, but the lag was not severe. When the test server (a 4-CPU UltraSPARC IV running Sun Solaris 10) was most stressed by those conditions, the fall-off did not seem to go above 40 percent'from an estimated 5 million messages per day processed to just under 3 million.
And of course, with IT, as soon as there is a problem, a company pops up to offer a solution. This is why we're seeing a new wave of vendors offering SOA governance tools. Such tools allow you 'to establish policies for how your IT initiatives will be deployed,' said Gregg Bjork, senior vice president for WebLayers Inc. of Cambridge, Mass., a vendor of such tools. Governance software can integrate with run-time systems. You can establish a policy that says a service must be executed in a certain time. If it isn't, an alert can be sent to a system administrator, who can then add more hardware or solve the problem in other ways.
Performance can be pepped up by other means as well. Enterprise Service Bus vendor Sonic Software Corp. of Bedford, Mass., offers a feature called itinerary based routing, in which the intraservice messages themselves carry the processing instructions. This approach eliminates the potential of the rules engine becoming the bottleneck of the system, said Dave Chappell, vice president and chief technology evangelist for Sonic.
Another aspect to keep in mind is that SOA does not equal Web Services. In fact, SOA can remain in place if we move beyond that technology stack. During Booch's talk, he said the beauty of SOA is that 'I can conceptualize my architectures as a set of services. As the protocols change out from under me, I can still maintain my architecture.'
'You want to move into an SOA in a way as to not bind you to the specific technology,' he said. 'Because the technology will change underneath you.'
Posted by Joab Jackson
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