Cloud Service Models - MetaTutorials


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Cloud Service Models

In cloud computing, following are the three basic models which are given according to the NIST definition of cloud: 
1. Saas (Software-as-a-Service)
2. Pass (Platform-as-a-service)
3. Iaas  (Infrastructure-as-a-Service)

Let's discuss each service model one by one. Here, you will get the introduction about each model with their characteristics, advantages, and disadvantages. 

Software-as-a-Service (SaaS)

The Software-as-a-Service (SaaS) is also called as a rentware or Subscribeware. Sometimes, it is also called as on-demand software
The applications of SaaS are also called as web-based and hosted software. 
It is a cloud-based method which provides the software services to the end-users through the Internet or an application. It is a model in which applications and services are hosted by the cloud service provider on the remote servers.
Any user can access the software services from internet instead of installing on their desktops. Users can run the software easily on any platform or any device. 
In the SaaS model, the software is licensed on the subscription basis and managed from a central location. Following are the some business applications for which SaaS become the common delivery model:
  • Database Management System (DBMS) Software,
  • Office Software,
  • CAD Software,
  • Development Software,
  • Messaging Software,
  • Virtualization,
  • Accounting,
  • Customer Relationship Management (CRM),
  • Enterprise Resource Planning (ERP),
  • Human Resource Management, and
  • Service Desk Management 
Examples of SaaS model are: Salesforce, Google Docs, word online, and slack. 

Characteristics or Features of SaaS

Following are the essential characteristics or features of the Software-as-a-Service (SaaS) model: 
1. The services provided by the SaaS are automatically updated and upgraded. 
2. The services can be scaled up or down on demand. 
3. SaaS provides the software for the users on the Internet.
4. The services are hosted on a remote server and managed by the cloud service provider.

Advantages of SaaS  

Following are the advantages or benefits of Software-as-a-Service (SaaS) model:
1. The main advantage of the SaaS model is that it is cost-effective because we have to pay only for what we have to use. 
2. The maintenance cost of the SaaS model is less. And, they also does not require any special software and hardware version. 
3. Multiple devices are supported by the SaaS model. We can easily access the services of SaaS from any device such as laptop, tablets, and desktops. 
4. The services of SaaS easily integrate with other services or software through the standard Application Programming Interface (API). 
5. Another big advantage of SaaS is that it is scalable. Because this model enables users to access the features or software on demand. 

Disadvantages of SaaS 

Following are the disadvantages or limitations of the Software-as-a-Service (SaaS) model: 
1. The applications used in SaaS must requires the Internet connection. We cannot access the software or services if the internet connection fails. 
2. There is a difficulty in switching between the SaaS vendors. 
3. Another disadvantage of SaaS is that it is insecure. The data is stored on the cloud so loss of data has a chance. 

Platform-as-a-Service (PaaS) 

Platform-as-a-Service (PaaS) is a cloud-based method which provides the platform and the runtime environment to the end-users for managing, running, and developing the applications and services. This service model is also hosted in the cloud remotely and accessed by the users via the Internet.
This service model also provides a framework for developers to create customized applications. It is basically designed for supporting the complete lifecycle of web application: building, testing, deploying, and managing.
This service model not only includes the network, server and storage but also include many more platforms such as database, tools, middleware, and business services to support the life cycle of the web application.

PaaS service model provides a new feature point-and-click tool, which allows non-developers to create or develop the web applications. 
Examples of PaaS model are: App Engine of Google, Azure,, Openshift. 

Characteristics or Features of PaaS

Following are the essential characteristics or features of Platform-as-a-Service (PaaS) model:
1. PaaS can be easily integrated with other applications on the same platform. 
2. This service model provides built-in security. It also provides the web service interface which enables the users to connect the applications outside the platform. 
3. It is built on the technology of virtualization. 
4. Multiple users can access through the same development application. 

Advantages of PaaS  

Following are the advantages or benefits of Platform-as-a-Service (PaaS) model:
1. The main advantage of PaaS is that it is simple and easy to use. 
2. Another advantage of PaaS is that it is cost-effective because there is no need to purchase the server or database to run the application. 
3. PaaS service model is also flexible because any user works on the application from anywhere any time with the help of the Internet. 
4. The members of the development team can work on the same project easily if they are in a remote location because the development environment is accessed over the Internet. 
5. Due to this service model, An IT team can focus on the development of the application rather than the maintenance of an application. 

Disadvantages of PaaS 

Following are the disadvantages or limitations of Platform-as-a-Service (PaaS) model: 
1. Due to the multi-tenant architecture, the security of data is the main issue in the PaaS model. 
2. When the application migrate from one PaaS vendor to other PaaS vendor, then it creates a problem. 
3. Some of the applications are from local and some are from the cloud, so due to this, there is a chance of increasing complexity.

Infrastructure-as-a-Service (IaaS)

Infrastructure-as-a-Service (IaaS) is a cloud-based method which provides the servers, networks, storage, virtual machines, and other resources to the users over the Internet. 
Any user can run the applications or operating systems on the rented servers without maintaining those servers. 
As compared to SaaS and PaaS service models, IaaS model offers the lowest-level control of resources in the cloud. 
Examples of IaaS model are: Microsoft Azure, Amazon Web Services, Rackspace and Google Compute Engine. 

Characteristics or Features of IaaS

Following are the essential characteristics or features of Infrastructure-as-a-Service (PaaS) model:
1. The IaaS model has the ability to quickly and easily scale the services. 
2. It provides the network hardware, servers, and storage. 
3. Multiple users can easily work on a single piece of hardware. 
4. This cloud service model is flexible and dynamic. 
5. We can use the resources on demand. 

Advantages of IaaS  

Following are the advantages or benefits of Infrastructure-as-a-Service (PaaS) model:
1. This service model enables more than one user for sharing the same physical infrastructure.
2. The users have to pay only for those services of IaaS which they want to use.
3. This service model frees up the IT team to focus on the core business of the organization rather than the infrastructure of IT.
4. One of the biggest advantages of this model is 'On-demand scalability'.
5. This service model can also be run even when the server goes down.

Disadvantages of IaaS 

Following are the disadvantages or limitations of Infrastructure-as-a-Service (PaaS) model: 
1. This service model depends on the virtualization services. 
2. It restricts the users privacy. 
3. The service providers of IaaS do not upgrade the software for some organizations.