Salesforce Google Edition

The more loosely coupled and distributed the cloud based system becomes, the more moving parts you don't have control over -- and the more hidden development costs lurking within this loose coupling.

Much of cloud functionality is created and hosted outside the organization, which creates ideal "pay as you go, leave when you want" cost and agility advantages, but it still requires testing, perhaps more than ever. To compound the problem "after the application is deployed, the service provider can make changes that could adversely affect the application without notice."

These needs call for automated testing and continuous validation. Then new two needs emerge as George notes. "After an application has been tested and deployed, paying per-unit of service (storage, CPU time, and bandwidth) allows a new app to get deployed with minimal cost. But these fixed costs can take a hidden toll when a company has to do any sort of testing, and particularly load and performance testing of a new app."

For instance, take a firm we know, whose operations team needed to run a performance test to verify required Service Level Agreements (SLAs) to verify that customer response times would be within bounds. One routine test cost about $10K in access fees from the service provider - an unforeseen bill that wouldn't have appeared if the team was banging on their own servers. That inhibits the team from testing and adjusting their service appropriately.

In addition, there is lack of control and ready access over many of these external services, especially if they are still being developed. This is where service virtualization comes in. Now you can bypass costs and areas where you cannot easily set up test situations on dependent services. As George notes, the methodologies and tools that were developed for SOA testing and validation will come in handy to handle cloud applications.

Of course, none of these challenges mean Cloud-based development isn't a great thing. We love it for all the reasons we loved SOA, then SaaS-based models, because it gives the enterprise incredible flexibility and lower cost of entry for needed infrastructure and applications. We are also seeing a new level of quality by pushing Virtual Services to provisioned Cloud environments for testing and performance labs, in order to keep unexpected third-party costs under control and allow unfettered access to test and development teams.

Expect to hear much more on this front as Cloud Computing gets tapped for serious, distributed enterprise applications that need validation and virtualization.