Cloud is a scalable service which can be accessed through internet connection with a higher bandwidth. When your organization is considering the cloud services for your applications, it is essential to know the basic differences between the cloud services. Since the cloud is a very broad concept, it covers the best possible online service. Generally there are three models in the cloud service which are under consideration, namely-
- Software as a Service (SaaS)
- Platform as a Service (PaaS)
- Infrastructure as a Service (IaaS)
Each of these cloud model services have their own complexity but still are essential to signify a particular cloud service which fulfill the IT needs. These service models are the three main standard models that fulfill their roles.
Software as a Service (SaaS)
SaaS is a on-demand licensing software and is the most widely used of all the service models in cloud computing. A complete functional software product is delivered to the users through the web by subscription which makes it a delivery model. We can use only the applications that are required for the business. The applications can be accessed by the users from devices like a mobile or a browser and they run on provider’s cloud infrastructure. The underlying cloud infrastructure includes network, servers, operating systems, load balancers, firewalls, storage and the runtime environment. The SaaS provider manages all these applications and services.
Every organization or a user who uses the SaaS is called as a Tenant and thereby this arrangement is also called as the Multitenant architecture. A well-defined feature set with fully facilitated services which are customizable is available with SaaS. SaaS providers offer APIs and browser-based interfaces are available for the users or developers which makes these services accessible and customizable. SaaS applications are used in customer relationship management, production or storage solutions like Salesforce, Google Apps or Drop Box. The servers are virtually partitioned and every user or organization can work with customised application instance. SaaS does not require any investment for licensing the software and this is the major benefit of it. It reduces the cost by decreasing the management staff to install, manage or upgrade the software and also cutting down the cost of licensing software. A consistent experience is achieved with Microsoft Online services that are subscription based and hosted services.
Platform as a Service (PaaS)
PaaS provides a platform on which software can be developed and deployed. It operates at a lower level than SaaS. With this model, we can run our own applications using optional building blocks and also get a core hosting operating system. PaaS providers usually deal with servers and give an environment where the operating system, server software, server hardware and network infrastructure are managed. The users can focus on the scalability and on the application development of their product without being concerned about the operating system, service packs or harware updates. PaaS is the one which uses the top virtualization technology. Rather than investing in repeated hardware, businesses can actually request their resources needed to them. Heroku, Google App Engine are the best examples of PaaS. Another example for PaaS is Microsoft Azure and SQL Azure, which are key components in the Azure Platform where Microsoft Azure is used as development, service management and service hosting whereas SQL Azure provide data services, relational database and data synchronization. On this platform you can deploy the custom applications and configure the applications as demand. PaaS removes the need to maintain the infrastructure that is used to develop applications.
Infrastructure as a Service (IaaS)
This is the most flexible and important computing model that comprises of scalable computer resources with network capability which is metered and self-provisioned. IaaS offers the cloud servers through the dashboard and APIs. IaaS clients can have direct access to the servers and storage with high scalability and also have a control on the infrastructure than SaaS and PaaS. IaaS gives access to the infrastructure that the software needs. With IaaS we can build a virtual data center. We need not invest much towards the maintenance and physical management. The major benefit of IaaS is that deployment of SaaS and PaaS, providing storage for data backups and high network bandwidth. The examples for IaaS are Softlayer, Exoscale, GCE (Google’s Compute Engine) and Navisite.