One key SOA tenet is that a distributed application environment should be platform-agnostic, and so should its governance infrastructure. Under pure SOA, the external API should be agnostic to the underlying platforms.

However, enterprise forays into cloud computing often violate that principle by relying on monolithic public-cloud services, most of which implement proprietary APIs, development tools, virtualization layers and governance features -- though many cloud services also incorporate open SOA and Web 2.0 standards to varying degrees. Interoperability among proprietary public clouds is often non-existent, and tools for governing services across diverse public and private clouds are just now coming to market.

To enable design-time cross-cloud service portability, public cloud providers should implement open industry standards for packaging of virtualized services," says Billy Marshall, founder and chief strategy officer of virtualization tool vendor rPath. "If we can define service compliance with an open virtualization format," says Marshall, "then we'll be able to define service governance that is independent of the host."

One specification that addresses this need is the Open Virtualization Format (OVF), a Distributed Management Task Force (DMTF) draft, which defines an extensible format for the packaging and distribution of software to be run in virtual machines (VM), such as those at the heart of public and private clouds. Though it is a key specification for portability of VMs across clouds, OVF, still in Version 1.0, does not provide the full context on VM "images" that would be necessary to support sophisticated life-cycle governance of these key artifacts, says Brett Adam, vice president of engineering at rPath.

VM sprawl adds further management complexity