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In today’s IT, there are a lot of discussions about different terms like PaaS, IaaS, and SaaS.  So what do all of these cloud acronyms mean?

I’m going to give you the simplest explanation I can, to help you understand the difference between SaaS, IaaS, and PaaS.

First, let’s expand those acronyms! Software as a Service, Infrastructure as a Service, and Platform as a Service are all just different types of clouds.

New Choices for Delivering IT

The cloud provides options for approach, sourcing, and control.  It delivers a well-defined set of services, which are perceived by the customers to have infinite capacity, continuous availability, increased agility, and improved cost efficiency. To achieve these attributes in their customers’ minds, IT must shift its traditional server-centric approach to a service-centric approach.  This implies that IT must go from deploying applications in silos with minimal leverage across environments to delivering applications on pre-determined standardized platforms with mutually agreed upon service levels.  A hybrid strategy that uses several cloud options at the same time will become the norm as organizations choose a mix of various cloud models to meet their specific needs.

Typical Service Models

Software as a Service

Software as a Service (SaaS) delivers business processes and applications, such as CRM, collaboration, and email, as standardized capabilities for a usage-based cost at an agreed, business-relevant service level. SaaS provides significant efficiencies in cost and delivery in exchange for minimal customization and represents a shift of operational risks from the consumer to the provider. All infrastructure and IT operational functions are abstracted away from the consumer.

Platform as a Service

Platform as a Service (PaaS) delivers application execution services, such as application runtime, storage, and integration for applications written for a pre-specified development framework. PaaS provides an efficient and agile approach to operate scale-out applications in a predictable and cost-effective manner. Service levels and operational risks are shared because the consumer must take responsibility for the stability, architectural compliance, and overall operations of the application while the provider delivers the platform capability (including the infrastructure and operational functions) at a predictable service level and cost.

Infrastructure as a Service

Infrastructure as a Service (IaaS) abstracts hardware (server, storage, and network infrastructure) into a pool of computing, storage, and connectivity capabilities that are delivered as services for a usage-based (metered) cost. Its goal is to provide a flexible, standard, and virtualized operating environment that can become a foundation for PaaS and SaaS.

IaaS is usually seen to provide a standardized virtual server. The consumer takes responsibility for configuration and operations of the guest Operating System (OS), software, and Database (DB). Compute capabilities (such as performance, bandwidth, and storage access) are also standardized.
Service levels cover the performance and availability of the virtualized infrastructure. The consumer takes on the operational risk that exists above the infrastructure.

Infrastructure as a Service with Azure Virtual Machines

In short, IaaS gives you a server in the cloud (virtual machine) that you have complete control over. With an Azure VM, you are responsible for managing everything from the Operating System on up to the application you are running.

On-demand data centers, also known as IaaS, provide compute power, memory, and storage, typically priced per hour, based on resource consumption. You pay only for what you use, and the service provides all the capacity you need, but you are responsible for monitoring, managing, and patching your on-demand infrastructure.

The biggest advantage of IaaS is that it offers a cloud-based data center without requiring you to install new equipment or to wait for the hardware procurement process. This means you can get IT resources that otherwise might not be available.

This mode of operation will feel most like a typical on premises virtual machine where you remote desktop into the server to manage it instead of sitting down in front of a physical keyboard and mouse.

Platform as a Service – Azure Cloud Services

An Azure Cloud Service consists of two components: your application files (source code, DLLs, etc.) and a configuration file. Together, these two elements will spin up a combination of Web Roles and Worker Roles to execute your application. With Cloud Services, Azure handles all of the tedious Operating System details for you, so you can focus on what matters – building a quality application for your users.

A Web Role is an Azure VM that is pre-configured as a web server (running IIS) and will automatically have your application loaded on it by the time the server fully spins up. This will create the public endpoint for your application – usually a website, but it could also be an API or something similar.

Worker Roles run alongside your Web Roles and are responsible for performing computing functions to support your application. Typically, the Web Role will accept some sort of user input and queue up an action for the Worker Role to process at a later time. This allows the Web Roles to be more responsive and to fire-and-forget tasks to be processed later.

Software as a Service – Basecamp, Salesforce, Office 365, Azure Websites

Finally, Software as a Service applications are built and hosted through 3rd party vendors who typically charge for a certain level of service – $30/month for X projects and Y users.

Azure Websites can serve as a SaaS offering as well. You can configure a WordPress, Drupal, OpenX, or even phpBB site with a single click. No code, no deployment hassles, and minimal configuration. Azure Websites lets you stand up the service you need in minutes, not hours or days.
Most SaaS applications today are built on a cloud platform due to the low cost of entry – with prices continually falling – and the ability to scale up as your customer base grows. If Dropcam, SmugMug, or Netflix got one million new customers tomorrow, their infrastructure (Amazon Web Services) would be able to accommodate them.

Conclusion

• Software-as-a-Service (SaaS) means you’re renting the app or software
• Platform-as-a-Service (PaaS) means that you’re renting everything but the app or software
• Infrastructure-as-a-Service (IaaS) means you’re renting only the hardware as well as the tools used to manage the hardware

While each Azure Compute (IaaS) offering has their pros and cons, I personally prefer to build my projects around PaaS. With PaaS, you get the maximum possible amount of flexibility before you have to start worrying about the tedious world of OS maintenance, versions, security, patches, etc.

Until next time, Rob.