IBM has recently submitted the IBM Cloud Computing Reference Architecture 2.0 (CC RA) (.doc) to the Cloud Architecture Project of the Open Group, a document based on “real-world input from many cloud implementations across IBM” meant to provide guidelines for creating a cloud environment.

CC RA emphasizes the synergies between cloud computing and SOA remarking that

The essential characteristics for Cloud Computing are on-demand self-service, broad network access, resource pooling, rapid elasticity, and measured Service. These characteristics can be found in requirements and SOA solutions in various organizations today, although these characteristics are optional for SOA and mandatory for cloud.

CC RA outlines four architectural layers proposed to be used in cloud computing:

- Operational Layer containing the basic cloud computing infrastructure
- Service Layer providing cloud services. IaaS is considered a service providing infrastructure along with PaaS offering middleware and SaaS providing applications.
- Business Process Layer. IBM introduces a new type of service called BPaaS providing business processes as services similar to what SOA offers.
- Consumer Layer. This is the layer consuming all the services generated by the previous layers.

Here is the document:

www.opengroup.org/cloudcomputing/uploads...mission.02282011.doc