Cloud Service Models
Infrastructure as a Service (IaaS)
This service model enables user organizations to forgo deployment of new datacenter equipment to handle growing operational needs. Rather, the business obtains needed IT infrastructure – servers, security, storage, networks, etc. – from a cloud services provider, often via a self-service catalog. While a user company can run applications, databases, operating systems and other software on top of its selected infrastructure, it has no direct control over or access to those machines. The cloud service provider manages the infrastructure, including any scaling up or down as needed.
Infrastructure as a Service is similar in concept to a traditional dedicated hosting service, with two major differences: Organizations tap into a shared, highly scalable pool of resources, and they pay for only what’s used on a utility basis. In other words, organizations can increase productivity while eliminating under utilization costs. IT shops must keep in mind, however, that multi-tenancy applies across the public cloud infrastructure. They have no way of controlling the types of virtual resources running atop the infrastructure they’ve provisioned from the cloud.
Platform as a Service (PaaS)
Derived from the SaaS model, PaaS caters to developers’ needs. Rather than simply delivering prepackaged applications via the on a service model, a PaaS provider offers up the entire computing platform and solutions stack needed for an application runtime environment. With PaaS, a company can deploy applications without incurring the associated upfront provisioning and ongoing maintenance and management costs of the underlying infrastructure. The user organization has application control, the caveat in many cases being that the developers must be comfortable with the PaaS provider’s choices for programming languages, interfaces, development tools, database support and the like.
The types of PaaS offerings vary; which option works best for a business depends on its goals. For example, some cloud companies offer a PaaS and SaaS combo, providing organizations with the ability to customize the packaged application. Although being able to tweak the application may make the SaaS model more attractive, the catch is that when combined with a PaaS offering, SaaS becomes less portable. The richest PaaS offerings enable an organization to support the entire application development lifecycle.
Software as a Service (SaaS)
Often geared toward the end user who needs access through a web browser or other thin clients, SaaS provides access to applications hosted on a service provider’s cloud infrastructure. A business can find just about any general office application available via the SaaS model. Customer relationship management (CRM), calendaring, e-mail and human resources management are among some of the more common applications delivered as services from the cloud infrastructure.
For IT departments, IT service management, spam filtering, intrusion prevention and other traditional security software are among the application types increasingly available via the SaaS model. With SaaS, the user organization neither owns the application nor the associated servers, operating systems, storage, network or other IT resources required for its support and delivery. For example, users can define their own firewall policies or white-label applications in their names.
Key Questions When Considering the Cloud
Some questions to ask internally before hopping on to the Cloud bandwagon:
Which parts of my business are suitable for moving to a cloud-based delivery model and which are not?
How much of each process should I consider placing on the cloud?
Should I retain control in-house but use cloud-based infrastructure, buy the entire process as a service, or something in between?
Which services are enterprise-ready and offer the right levels of security and governance for my business?
How does transitioning to a cloud impact my procurement and what else should I consider before signing on the dotted line?
- How do I establish a winning strategy to fulfill short-term needs and provide long-term advantage by leveraging virtualization and cloud?