Software Engineering Institute

December 9, 2009—In recent months, technology news headlines have been dominated by cloud computing—a large-scale model in which computing power, software, storage services, and platforms are delivered on demand to external customers. The latest news came in mid-September with the announcement of apps.gov, a government website where federal agencies will be able to buy cloud computing applications and services to replace on-site systems.

There are two types of clouds. Public clouds are offered over an Internet connection and require users to pay a usage fee. Private clouds are deployed inside firewalls and managed by the user organization.

The enthusiasm around cloud computing sounds eerily familiar to Grace Lewis, a researcher with the SEI’s Research, Technology, and System Solutions (RTSS) program and team lead for its work in system of systems engineering. For several years, Lewis has been instrumental in the development of the Service Migration and Reuse Technique (SMART), a process that is helping organizations in government and industry determine whether service-oriented architecture (SOA) adoption fits their needs.

“One thing the SEI stands for is separating reality from hype about promising technologies. One of our duties is to keep on top of things that are big or becoming big,” explained Lewis, who is now leading research into cloud computing at the SEI.

Tempering the hype about cloud computing as the next technology “silver bullet,” Lewis said one of the first things to know is that cloud computing is mostly driven by economics.

“It’s an economic model where organizations have to study the benefits of leasing resources instead of owning them,” Lewis explained. “Instead of having 20 servers deployed inside an organization, which cost money and time to maintain, an organization might benefit if those servers were located off-site.”

Lewis said that security is another area to consider, particularly for organizations that place their data on external servers in the cloud.

“If that data is sensitive, people have to think about what potential dangers there are when data resides outside the organization,” Lewis said.

Beyond those considerations, Lewis points out that cloud computing environments can drive requirements for an organization’s systems, whether that system is new or modified. “When you’re building from scratch, you have more play room. When resources from the cloud are incorporated into a systems solution, systems have to be architected to take advantage of the cloud without sacrificing system qualities, which will require tradeoffs,” Lewis said.

A popular notion that Lewis debunks is the idea that cloud computing is a substitute for SOA. “That would be an example of hype. They’re complementary, but they don’t replace each other,” Lewis explained. An organization might place raw data in the cloud and then build its own service infrastructure on top of it to sort and manage that data.

“From the user perspective, a key for success with cloud computing is defining your requirements so that your users get the response time they want, and your organization gets the security it needs,” Lewis advised.

Lewis discussed her work on cloud computing in an SEI webinar. The on-demand webinar is available on the SEI website.