Cloud services from a common infrastructure

 

As applications begin to consume platform services, the IaaS framework is likely to take on the appearance of a data center optimized for service-oriented architecture (SOA). The idea of the user providing a “machine image” is replaced by the idea of the user providing an application to catalog—an application that will be represented in an SOA directory (UDDI) and instantiated on demand, using the provider’s virtual machines. This represents PaaS services as effectively an SOA overlay on IaaS infrastructure, a model that seems explicitly adopted by Microsoft with Azure and by IBM with its Cloud Service Provider Platform.

 

Platform services are represented as SOA services and accessed as any internal software service would be accessed. This also facilitates the integration of PaaS cloud services with enterprise software; any SOA tool can provide the binding required.

Software as a Service. Moving up the stack to SaaS, we again find that the next level of cloud services can begin as an extension of the last. The SOA abstraction of a “service” can be applied both to application components and to entire applications. In the former case, a SaaS offering would be associated with a SOA-compatible interface (including Simple Object Access Protocol, SOAP), and could be registered as a service in a SOA directory for access as described with a PaaS cloud service. In this case, an enterprise might be consuming a cloud SaaS component within an application otherwise hosted in-house.

 

If the entire application were to be represented as a service, then the SaaS offering could be made through a traditional URL or RESTful interface and be accessed by a browser. This would be the type of SaaS service that well-known Salesforce.com provides. Operators could provide these types of services directly (using open source software, licensed software or software they develop), or they could offer wholesale PaaS or IaaS support to third parties that would then offer SaaS services.

 

Cloud services at the higher levels, which include SaaS and PaaS, displace more user support and license costs and, therefore, justify higher prices. If operators can use the same infrastructure to offer these services as they use for the more general IaaS services, they can increase their profits and provide cloud services more easily integrated with enterprise IT. That can be particularly valuable in addressing the data center backup and application overflow opportunities that enterprises value most highly for cloudsourcing.