A Brief Summary of IaaS, PaaS, SaaS

Cloud computing has transformed the way of  IT departments manage and deploy software. 

Cloud is a kind of an Internet based Service offered on-demand to a User who doesn’t need to bother with implementation details or maintenance infrastructure. Whether it’s SaaS, PaaS, or IaaS, there is a suitable cloud service to fulfill virtually any IT need imaginable.

Let us now try and understand the difference between these.

Infrastructure as a Service (IaaS)   

•  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. 
• 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.  EX: Softlayer, Exoscale, GCE (Google’s Compute Engine) and NaviSite.
• With the IaaS model, you can outsource the elements of infrastructure like Virtualization, Storage, Networking, and Load Balancers and so on, to a Cloud Provider like Microsoft.
• To deploy your applications to the Cloud, you have to install OS images and related application software on the cloud infrastructure. In this model, it’s your responsibility to patch/ update/maintain the OS and any application software you install.
• The Cloud provider will typically bill you on computing power by the hour and a number of resources allocated and consumed (as per its service level agreement (SLA). 

Platform as a Service (PaaS)

• PaaS as a cloud service model where the cloud is used to deliver a platform to users, from which they can develop, initialize and manage applications. PaaS offerings typically include a base operating system and a suite of applications and development tools
•  PaaS eliminates the need for organizations to build and maintain the infrastructure traditionally used to develop applications. PaaS is sometimes called ‘middleware’, referring to how it conceptually sits somewhere between SaaS and IaaS.
• Platform’s like Google’s App Engine, IBM BlueMix, and Apache’s Stratos are popular PaaS products which are helping to streamline and democratize software development.
• What exactly is the service? With the PaaS model, you get a core hosting operating system and optional building block services that allow you to run your own applications or third-party applications. You need not be concerned about lower level elements of Infrastructure, Network Topology, Security and Load Balancers — all this is done for you by the Cloud Service Provider. The Provider gives you a fully functional OS with major platform software.
• The key feature One of the key benefits of PaaS is that you need not be concerned about the running OS or updates (service packs) and hardware upgrades. The Provider regularly patches your OS, updates platform features (such as the core .NET platform or SQL database engine) and updates hardware on demand to meet your demand

Software as a Service (SaaS) 

• SaaS is a cloud service that provides users access to software in a self-service, on-demand fashion. This could be a single application or provide a catalog of software a user might choose from. The simplest form of cloud service and that’s what makes it special. It directly serves the end user
• SaaS is 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.

The Multitenant architecture

• The system of arrangement is commonly known as the multitenant architecture. 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.
• SaaS providers offer APIs and browser-based interfaces are available for the users or developers which make these services accessible and customizable.
• SaaS applications are used in customer relationship management, production or storage solutions like Salesforce, Google Apps or Drop Box.
• With the SaaS model, you consume as a service only the Applications that you need for your business. These applications run on the provider’s cloud infrastructure, making them accessible from various devices like browser or mobile.

In a broad spectrum

Though each of these services has its own limitations, the cloud is a broad concept and a scalable service which can be accessed through the internet connection with a higher bandwidth.