Lets Understand Cloud Computing Stack...

SERVICE MODELS

Software as a Service (SaaS) - The capability provided to the consumer is to use the provider’s applications running on a cloud infrastructure. The applications are accessible from various client devices through either a thin client interface, such as a web browser (e.g., web-based email), or a program interface. The consumer does not manage or control the underlying cloud infrastructure including network, servers, operating systems, storage, or even individual application capabilities, with the possible exception of limited user-specific application configuration settings.

 

Platform as a Service (PaaS) - The capability provided to the consumer is to deploy onto the cloud infrastructure consumer-created or acquired applications created, using programming languages, libraries, services, and tools supported by the provider. The consumer does not manage or control the underlying cloud infrastructure including network, servers, operating systems, or storage but has control over the deployed applications and possibly configuration settings for the application-hosting environment.

Infrastructure as a Service (IaaS) - The capability provided to the consumer is to provision processing, storage, networks, and other fundamental computing resources where the consumer is able to deploy and run arbitrary software which can include operating systems and applications. The consumer does not manage or control the underlying cloud infrastructure but has control over operating systems, storage, and deployed applications; and possibly limited control of select networking components (e.g., host firewalls).

DEPLOYMENT MODELS

• Private Cloud - The cloud infrastructure is provisioned for exclusive use by a single organization comprising multiple consumers (e.g., business units). It may be owned, managed, and operated by the organization, a third party, or some combination of them, and it may exist on or off premises.

• Community Cloud - The cloud infrastructure is provisioned for exclusive use by a specific community of consumers from organizations that have shared concerns (e.g., mission, security requirements, policy, and compliance considerations). It may be owned, managed, and operated by one or more of the organizations in the community, a third party, or some combination of them, and it may exist on or off premises.

• Public Cloud - The cloud infrastructure is provisioned for open use by the general public. It may be owned, managed, and operated by a business, academic, or government organization, or some combination of them. It exists on the premises of the cloud provider.

• Hybrid Cloud - The cloud infrastructure is a composition of two or more distinct cloud infrastructures (private, community, or public) that remain unique entities, but are bound together by standardized or proprietary technology that enables data and application portability (e.g., cloud bursting for load balancing between clouds).

30 years ago, connections through the “cloud” were very expensive and typically only available through the incumbent (monopoly) telecommunications provider. Users would be large enterprises with the need for accessing common data in different locations, such as between Head and Regional or Branch Offices. The development of the Internet as a service environment supporting relatively low cost devices and storage capacity has led to the current growth in “cloud computing”. The commoditisation of services and applications through mobile devices has created a generation of consumers/end-users who accept the “cloud” environment as the normal way to access information, services and communications. This, in turn, has put pressure on large enterprises because the barriers to entry have been lowered through cloud computing. Small medium Enterprise have largely benefited through the introduction of cloud in that they are now able to compete head to head with large enterprises. They no longer have to invest hardware and software installations and updates.

Now that we have given background to cloud computing world and how it works, the next blog will explain in detail the benefits and limitations of cloud and also propose suggestions on how enterprises can overcome these limitations. We will also share views from a cloud conference held in Johannesburg organised by ITWEB supported by Microsoft SA on the Economic Impact of cloud computing on South African SMME’s.

References:

• Armbrust, M., Fox, A., Griffith, R., Joseph, A. D., Katz, R., Konwinski, A., ... & Zaharia, M. (2010). A view of cloud computing. Communications of the ACM, 53(4), 50-58.
• Subashini, S., & Kavitha, V. (2011). A survey on security issues in service delivery models of cloud computing. Journal of Network and Computer Applications, 34(1), 1-11.