Cloud Interoperability

Since the internet is a network of network, so Inter cloud seems plausible.

A network offers high level services for transportation of digital information from a source or a host outside the network to destination, another host or another network that can deliver the information to its final destination. This transportation of information is possible because there is agreement on a) how to uniquely indentify the source and destination of the information b)how to navigate through a maze of networks  and c) how to actually transport the data between a source and a destination. The three elements on which agreement is in place are IP address, IP protocol, and transportation protocol such as TCP/UDP.

In case of cloud there are no standards for storage or processing, the clouds have different delivery models which are not only large but also open. But following the lines of internet cloud interoperability seems feasible.  Standards are required for items such as naming, addressing, identity, trust, presence, message, multicast, time, means to transfer, store and process information etc.  An inter cloud would require the development of an ontology for cloud computing and then each service provider would have to create a description of all resources and services using this ontology. Each cloud would then require an interface which may be termed as an Inter cloud Exchange to translate the common language describing all object and action included in a request originating from another cloud in terms of internal objects and action.

 The above diagram show communication among disparate clouds

The Open Grid Forum has created a working group to standardize such an interface called as the Open Cloud Computing Interface (OCCI).  The OCCI has adopted resource oriented architecture (ROA) to represent key components comprising cloud infrastructure service.  Each resource identified by a URI (Unique resource identifier) can have multiple representations that may or may not be hypertext. The OCCI working group plans to map API to several formats. Thus a single URI entry point defines an OCCI interface.

The API implements CRUD operations: Create, Retrieve, update and delete. Each is mapped to HTTP POST, GET, PUT and DELETE respectively. OCCI provides the capabilities to govern the definition, creation, deployment, operation and retirement of infrastructure services. 

Cloud clients can invoke a new application stack, manage its life cycle and manage the resources that it uses using the OCCI.  The SINA association has established a working group to address the standardization of cloud storage.  The cloud Management Data Interface (CDMI) serves the purpose. In CDMI the storage space exposed by various type of interface is abstracted using the notion of a container.   The container also serves as a grouping of the data storage in the storage space and also forms a point of control for applying data services in aggregation. The CDMI provider data object interface with CRUD semantics and can also be used to manage containers exported for use by cloud infrastructure.

The above diagram shows OCCI and CDMI in an integrated cloud environment

To achieve interoperability, CDMI provides a type of export that contains information obtained via the OCCI interface. In addition, OCCI provide a type of storage that corresponds to exported CDMI containers.