Cloud Computing

As discussed in the previous chapter, the NIST model of cloud computing treats the computing methodology from two perspectives as deployment and as service. While cloud can be deployed in four possible ways, the services it offers can be categorized primarily into three different types.

Apart from three primary cloud services, computing vendors deliver a number of specialized cloud services which are considered as special services under these three primary cloud services. In order to understand how cloud computing can be of value to consumers, it is important to understand the services it offers. This chapter focusses on all of these service delivery models.

There are many vendors who provide different cloud services in the market today. Along with proprietary public cloud services, many open-source initiatives are also available which mainly focus on to create private as well as hybrid cloud environments. Few among those open-source initiatives have also been discussed in this chapter.

SERVICE DELIVERY MODELS

Three categories of computing services that people consume from the days of traditional computing have been already mentioned in the first chapter. They are:

Cloud computing talks about delivering these facilities to consumers as computing services through network/internetwork. The benefit for the consumers is that they can avail these facilities over Internet anytime, as much as required, sitting at their own locations in a cost-effective manner. They only need to have a simple and suitable access device (like PC, laptop, tablet, mobile etc.) to access these services. Using these simple devices anyone can access any kind of computing infrastructure, platform or software application on payment-as-per-actual-usage basis.

Cloud computing offers computing infrastructure, platform and application delivered ‘as-a-service’. Those services are considered as primary cloud computing services and are referred to as:

These services are generally pronounced as ‘i-a-a-s’, ‘pass’, and ‘saas’ respectively. They are the driving forces behind the growth of cloud computing. Clubbed together these three service models are commonly referred as SPI (Service-Platform-Infrastructure) model. Cloud service providers arrange these services for the cloud consumers. The NIST reference architecture represents these services under ‘service orchestration’ component of the providers (Figure 5.1).