Cloud computing has come a very long ways. The concepts, usage and opinion about cloud computing has changes a lot over the years. While few companies have started to adopt with open arms, others still are concerned about the security aspect.

The SPI Model mentioned above is commonly termed as Cloud Computing Stacks in technical terms and I have tried to explain the terms with in common language thereby removing the layer of complexity.

SaaS – Software-as-a-Service
Software that is deployed and available on the Internet, which users can access as and when required. This is also termed as “software on demand”. Examples include Salesforce.com sales management applications, NetSuite, Google’s Gmail, Facebook and many others. Monay of the companies have also started providing their software though internet on payment or subscription basis which includes Microsoft Office Package and other ERP suites.
Payment can either be as per usage, on a subscription model or licensing model or sometimes even free.
While SaaS offers several advantages like accessibility from any location, rapid scalability as and when required and no concerns for maintenance and updates, there may be certain security concerns, especially for customers who desire high security and control on their database such as banking industry, as that domain is in the hands of the provider and is more susceptible to hacking of data.
SaaS may be considered the oldest and most mature type of cloud computing.

Due to its low entry costs and substantial benefits – including faster application deployment, greater flexibility and improved employee productivity – Software-as-a-Service adoption is skyrocketing across all industry verticals. This includes unique purpose-built applications as well as general business applications.
For many organizations, leveraging SaaS can provide a better operational model to drive change for both the business and IT, providing benefits from efficiencies not previously possible with on-premise applications to lowering overall operations costs.

PaaS – Platform-as-a-Service
Platform as a Service (PaaS) brings the benefits that SaaS bought for applications, but over to the software development world. PaaS can be defined as a computing platform on internet that allows the creation of web applications quickly and easily and without the complexity of buying and maintaining the software and infrastructure underneath it.
It is a combination of a development platform and a solution stack, delivered as a development service on demand. It provides the entire application development platform to software developers thereby reducing the cost and complexity of buying and managing the underlying hardware and software and provisioning hosting capabilities. In other words, it provides the supporting infrastructure to enable the end user develop his own solutions.

Characteristics of PaaS

There are a number of different takes on what constitutes PaaS but some basic characteristics include:
          Services to develop, test, deploy, host and maintain applications in the same integrated development environment. All the varying services needed to fulfil the application development process
          Web based user interface creation tools help to create, modify, test and deploy different UI scenarios
          Multi-tenant architecture where multiple concurrent users utilize the same development application
          Built in scalability of deployed software including load balancing and failover
          Integration with web services and databases via common standards
          Support for development team collaboration – some PaaS solutions include project planning and communication tools
          Tools to handle billing and subscription management Sometimes,
          PaaS is used to extend the capabilities of applications developed as SaaS. Examples of PaaS include Salesforce.com’s Force.com, Google’s App Engine, and Microsoft’s Azure.




IaaS – Infrastructure-as-a-Service
Infrastructure as a Service (IaaS) is a way of delivering Cloud Computing infrastructure – servers, storage, network and operating systems – as an on-demand service. Rather than purchasing servers, software, datacenter space or network equipment, clients instead buy those resources as a fully outsourced service on demand as and when required. IaaS is generally used by organizations that have the in-house expertise to manage their IT requirements but don’t have the infrastructure. They then hire the required infrastructure from IaaS providers and load up their libraries, applications, and data, after which they configure them themselves.
A popular use of IaaS is in hosting websites, where the in-house infrastructure is not burdened with this task but left free to manage the business. Amazon’s Elastic Compute Cloud (EC2), Rackspace and GoGrid’s ServePath is a major example of IaaS.

Characteristics of IaaS
As with the two previous sections, SaaS and PaaS, IaaS is a rapidly developing field. That said there are some core characteristics which describe what IaaS is. IaaS is generally accepted to comply with the following;
          Resources are distributed as a service
          Allows for dynamic scaling
          Has a variable cost, utility pricing model
          Generally includes multiple users on a single piece of hardware


18 Responses so far.

  1. Anonymous says:

    Very useful and knowledgeable information you have shared about the Cloud Computing Stacks. I appreciate your great effort.
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  2. Unknown says:

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  7. Upraise says:

    Nice blog on SaaS Services. You can read about objective and key results here as it adds into SaaS services.

  8. Miles says:

    The Software Process Improvement (SPI) model is a structured approach to enhance software development processes. Device Streaming Slow It's a roadmap for organizations to optimize efficiency, quality, and project outcomes.

  9. Thanks for sharing it. I always enjoy reading such superb content with valuable information. The ideas presented are excellent and really cool, making the post truly enjoyable. Keep up the fantastic work.
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