Service Models

IaaS(Infrastructure as a Service)

Infrastructure as a Service (IaaS) is one of the three fundamental service models of cloud computing alongside Platform as a Service (PaaS) and Software as a Service (SaaS). As with all cloud computing services it provides access to computing resource in a virtualised environment, “the Cloud”, across a public connection, usually the internet. In the case of IaaS the computing resource provided is specifically that of virtualised hardware, in other words, computing infrastructure. The definition includes such offerings as virtual server space, network connections, bandwidth, IP addresses and load balancers. Physically, the pool of hardware resource is pulled from a multitude of servers and networks usually distributed across numerous data centers, all of which the cloud provider is responsible for maintaining. The client, on the other hand, is given access to the virtualised components in order to build their own IT platforms.

In common with the other two forms of cloud hosting, IaaS can be utilized by enterprise customers to create cost effective and easily scalable IT solutions where the complexities and expenses of managing the underlying hardware are outsourced to the cloud provider. If the scale of a business customer’s operations fluctuate, or they are looking to expand, they can tap into the cloud resource as and when they need it rather than purchase, install and integrate hardware themselves.

The following are salient examples of how IaaS can be utilized by enterprise:

  • Enterprise infrastructure; by internal business networks, such as private clouds and virtual local area networks, which utilise pooled server and networking resources and in which a business can store their data and run the applications they need to operate day-to-day. Expanding businesses can scale their infrastructure in accordance with their growth whilst private clouds (accessible only by the business itself) can protect the storage and transfer of the sensitive data that some businesses are required to handle.
  • Cloud hosting; the hosting of websites on virtual servers which are founded upon pooled resources from underlying physical servers. A website hosted in the cloud, for example, can benefit from the redundancy provided by a vast network of physical servers and on demand scalability to deal with unexpected demands placed on the website.
  • Virtual Data Centers (VDC);  a virtualised network of interconnected virtual servers which can be used to offer enhanced cloud hosting capabilities, enterprise IT infrastructure or to integrate all of these operations within either a private or public cloud implementation.

A typical Infrastructure as a Service offering can deliver the following features and benefits:

  • Scalability; resource is available as and when the client needs it and, therefore, there are no delays in expanding capacity or the wastage of unused capacity
  • No investment in hardware; the underlying physical hardware that supports an IaaS service is set up and maintained by the cloud provider, saving the time and cost of doing so on the client side
  • Utility style costing; the service can be accessed on demand and the client only pays for the resource that they actually use
  • Location independence; the service can usually be accessed from any location as long as there is an internet connection and the security protocol of the cloud allows it
  • Physical security of data center locations; services available through a public cloud, or private clouds hosted externally with the cloud provider, benefit from the physical security afforded to the servers which are hosted within a data center
  • No single point of failure; if one server or network switch, for example, were to fail, the broader service would be unaffected due to the remaining multitude of hardware resources and redundancy configurations.  For many services if one entire data center were to go offline, never-mind one server, the IaaS service could still run successfully.

PaaS(Platform as Service)

Platform as a Service, often simply referred to as PaaS, is a category of cloud computing that provides a platform and environment to allow developers to build applications and services over the internet. PaaS services are hosted in the cloud and accessed by users simply via their web browser.

Platform as a Service allows users to create software applications using tools supplied by the provider. PaaS services can consist of preconfigured features that customers can subscribe to; they can choose to include the features that meet their requirements while discarding those that do not. Consequently, packages can vary from offering simple point-and-click frameworks where no client side hosting expertise is required to supplying the infrastructure options for advanced development.

The infrastructure and applications are managed for customers and support is available. Services are constantly updated, with existing features upgraded and additional features added. PaaS providers can assist developers from the conception of their original ideas to the creation of applications, and through to testing and deployment. This is all achieved in a managed mechanism.

As with most cloud offerings, PaaS services are generally paid for on a subscription basis with clients ultimately paying just for what they use. Clients also benefit from the economies of scale that arise from the sharing of the underlying physical infrastructure between users, and that results in lower costs.

Below are some of the features that can be included with a PaaS offering:

  • Operating system
  • Server-side scripting environment
  • Database management system
  • Server Software
  • Support
  • Storage
  • Network access
  • Tools for design and development
  • Hosting

Software developers, web developers and businesses can benefit from PaaS. Whether building an application which they are planning to offer over the internet or software to be sold out of the box, software developers may take advantage of a PaaS solution. For example, web developers can use individual PaaS environments at every stage of the process to develop, test and ultimately host their websites. However, businesses that are developing their own internal software can also utilise Platform as a Service, particularly to create distinct ring-fenced development and testing environments.

Below are some of the benefits of PaaS to application developers:

  • They don’t have to invest in physical infrastructure; being able to ‘rent’ virtual infrastructure has both cost benefits and practical benefits. They don’t need to purchase hardware themselves or employ the expertise to manage it. This leaves them free to focus on the development of applications. What’s more, clients will only need to rent the resources they need rather than invest in fixed, unused and therefore wasted capacity.
  • Makes development possible for ‘non-experts’; with some PaaS offerings anyone can develop an application. They can simply do this through their web browser utilising one-click functionality. Salient examples of this are one-click blog software installs such as WordPress.
  • Flexibility; customers can have control over the tools that are installed within their platforms and can create a platform that suits their specific requirements. They can ‘pick and choose’ the features they feel are necessary.
  • Adaptability; Features can be changed if circumstances dictate that they should.
  • Teams in various locations can work together; as an internet connection and web browser are all that is required, developers spread across several locations can work together on the same application build.
  • Security; security is provided, including data security and backup and recovery.

In summary, a PaaS offering supplies an operating environment for developing applications. In other words, it provides the architecture as well as the overall infrastructure to support application development. This includes networking, storage, software support and management services. It is therefore ideal for the development of new applications that are intended for the web as well as mobile devices and PCs

SaaS(Software as a Service)

SaaS, or Software as a Service, describes any cloud service where consumers are able to access software applications over the internet. The applications are hosted in “the cloud” and can be used for a wide range of tasks for both individuals and organizations. Google, Twitter, Facebook and Flickr are all examples of SaaS, with users able to access the services via any internet enabled device. Enterprise users are able to use applications for a range of needs, including accounting and invoicing, tracking sales, planning, performance monitoring and communications (including web-mail and instant messaging).

SaaS is often referred to as software-on-demand and utilizing it is akin to renting software rather than buying it. With traditional software applications you would purchase the software upfront as a package and then install it onto your computer. The software’s licence may also limit the number of users and/or devices where the software can be deployed. Software as a Service users, however, subscribe to the software rather than purchase it, usually on a monthly basis. Applications are purchased and used online with files saved in the cloud rather than on individual computers.

There are a number of reasons why SaaS is beneficial to organizations and personal users alike:

  • No additional hardware costs; the processing power required to run the applications is supplied by the cloud provider.
  • No initial setup costs; applications are ready to use once the user subscribes.
  • Pay for what you use; if a piece of software is only needed for a limited period then it is only paid for over that period and subscriptions can usually be halted at any time.
  • Usage is scalable; if a user decides they need more storage or additional services, for example, then they can access these on demand without needing to install new software or hardware.
  • Updates are automated; whenever there is an update it is available online to existing customers, often free of charge. No new software will be required as it often is with other types of applications and the updates will usually be deployed automatically by the cloud provider.
  • Cross device compatibility; SaaS applications can be accessed via any internet enabled device, which makes it ideal for those who use a number of different devices, such as internet enabled phones and tablets, and those who don’t always use the same computer.
  • Accessible from any location; rather than being restricted to installations on individual computers, an application can be accessed from anywhere with an internet enabled device.
  • Applications can be customized and white labelled; with some software, customization is available meaning it can be altered to suit the needs and branding of a particular customer.

Office software is the best example of businesses utilizing SaaS. Tasks related to accounting, invoicing, sales and planning can all be performed through Software as a Service. Businesses may wish to use one piece of software that performs all of these tasks or several that each perform different tasks. The required software can be subscribed to via the internet and then accessed online via any computer in the office using a username and password. If needs change they can easily switch to software that better meets their requirements. Everyone who needs access to a particular piece of software can be set up as a user, whether it is one or two people or every employee in a corporation that employs hundreds.

 Summary

  • There are no setup costs with SaaS, as there often are with other applications
  • SaaS is scalable with upgrades available on demand
  • Access to Software as a Service is compatible across all internet enabled devices
  • As long as there is an internet connection, applications are accessible from any location