Computers · Technology

Understanding the Cloud Computing Stack: SaaS, PaaS, IaaS

Cloud Computing is often described as a stack, as a response to the broad range of services built on top of one another under the moniker “Cloud”. The generally accepted definition of Cloud Computing comes from the National Institute of Standards and Technology (NIST). The NIST definition runs to several hundred words but essentially says that;
Cloud computing is a model for enabling convenient, on-demand network access to a shared pool of configurable computing resources that can be rapidly provisioned and released with minimal management effort or service provider interaction.

What this means in plain terms is the ability for end users to utilize parts of bulk resources and that these resources can be acquired quickly and easily.

NIST also offers up several characteristics that it sees as essential for a service to be considered “Cloud”. These characteristics include;

• On-demand self-service. The ability for an end user to sign up and receive services without the long delays that have characterized traditional IT
• Broad network access. Ability to access the service via standard platforms
• Resource pooling. Resources are pooled across multiple customers
• Rapid elasticity. Capability can scale to cope with demand peaks
• Measured Service. Billing is metered and delivered as a utility service

More than a semantic argument around categorization, we believe that in order to maximize the benefits that Cloud Computing brings, a solution needs to demonstrate these particular characteristics. This is especially true since in recent years there has been a move by traditional software vendors to market solutions as “Cloud Computing” which are generally accepted to not fall within the definition of true Cloud Computing, a practice known as “cloud-washing.”

The diagram below depicts the Cloud Computing stack – it shows three distinct categories within Cloud Computing: Software as a Service, Platform as a Service and Infrastructure as a Service.

In this report we look at all three categories in detail however a very simplified way of differentiating these flavors of Cloud Computing is as follows;

• SaaS applications are designed for end-users, delivered over the web
• PaaS is the set of tools and services designed to make coding and deploying those applications quick and efficient.
• IaaS is the hardware and software that powers it all – servers, storage, networks, operating systems

To help understand how these 3 components are related, some have used a transportation analogy;

It is important to note that while for illustration purposes this whitepaper draws a clear distinction between SaaS, PaaS and IaaS, the differences between these categories of cloud computing, especially PaaS and IaaS, have blurred in recent months and will continue to do so. Nevertheless, with a general understanding of how these components interact with each other, we will turn our attention in more detail to the top layer of the stack, SaaS.

Software as a Service

Software as a Service (SaaS) is defined as ;

software that is deployed over the internet. With SaaS, a provider licenses an application to customers either as a service on demand, through a subscription, in a “pay-as-you-go” model, or (increasingly) at no charge when there is opportunity to generate revenue from streams other than the user, such as from advertisement or user list sales
SaaS is a rapidly growing market as indicated in recent reports that predict ongoing double digit growth . This rapid growth indicates that SaaS will soon become commonplace within every organization and hence it is important that buyers and users of technology understand what SaaS is and where it is suitable.

Characteristics of SaaS

Like other forms of Cloud Computing, it is important to ensure that solutions sold as SaaS in fact comply with generally accepted definitions of Cloud Computing. Some defining characteristics of SaaS include;

• Web access to commercial software
• Software is managed from a central location
• Software delivered in a “one to many” model
• Users not required to handle software upgrades and patches
• Application Programming Interfaces (APIs) allow for integration between different pieces of software

Where SaaS Makes Sense

Cloud Computing generally, and SaaS in particular, is a rapidly growing method of delivering technology. That said, organizations considering a move to the cloud will want to consider which applications they move to SaaS. As such there are particular solutions we consider prime candidate for an initial move to SaaS;

• “Vanilla” offerings where the solution is largely undifferentiated. A good example of a vanilla offering would include email where many times competitors use the same software precisely because this fundamental technology is a requirement for doing business, but does not itself confer an competitive advantage
• Applications where there is significant interplay between the organization and the outside world. For example, email newsletter campaign software
• Applications that have a significant need for web or mobile access. An example would be mobile sales management software
• Software that is only to be used for a short term need. An example would be collaboration software for a specific project
• Software where demand spikes significantly, for example tax or billing software used once a month

SaaS is widely accepted to have been introduced to the business world by the Salesforce. Customer Relationship Management (CRM) product. As one of the earliest entrants it is not surprising that CRM is the most popular SaaS application area, however e-mail, financial management, customer service and expense management have also gotten good uptake via SaaS.

Where SaaS May Not be the Best Option

While SaaS is a very valuable tool, there are certain situations where we believe it is not the best option for software delivery. Examples where SaaS may not be appropriate include;

• Applications where extremely fast processing of real time data is required
• Applications where legislation or other regulation does not permit data being hosted externally
• Applications where an existing on-premise solution fulfills all of the organization’s needs

Software as a Service may be the best known aspect of Cloud Computing, but developers and organizations all around the world are leveraging Platform as a Service, which mixes the simplicity of SaaS with the power of IaaS, to great effect.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s