Introduction

Cloud Computing means hosting your server, storage, database, networking, or software related services on the Internet.Today, all businesses, regardless of their size, are talking about or even considering availing cloud services. However, as businesses move towards adopting cloud solutions, it is important for them to understand the differences between, and the advantages and limitations of different types of cloud services.

Following are the three main models of cloud services:

Software as a Service (SaaS)

Platform as a Service (PaaS)

Infrastructure as a Service(IaaS)

SaaS: Software as a Service

Software as a Service, also known as cloud application services, is the most commonly used model. SaaS leverages the Internet to deliver third-party vendor-managed applications to its users. Most SaaS applications run directly through a web browser, and therefore, do not require any downloads or installations on the client side.

SaaS Delivery

As SaaS runs on a web delivery model, it eliminates the need to have IT staff download or install applications on each individual computer. All technical issues, such as data, middleware, servers, etc. are managed by vendors, which streamlines maintenance and support activities for businesses.

SaaS Advantages

1. Reduction in money and time spent on managing, installing, and upgrading software, which can be spent on more crucial tasks within the organization.

SaaS Characteristics

1.Managed from a central location

2.Accessible over Internet

3.Hosted on a remote server

4.Users are not responsible for hardware and software updates

When to use SaaS

1.Startups or small companies that cannot invest too much time on fixing server or software issues.

2.Short term projects that involve easy and quick collaboration

3.Applications that needs both mobile and web access

4.Scenarios where apps run 24/7 applications and need to be available to users irrespective of where they are.

SaaS Limitations and Concerns

1.Data Security: In order to perform certain actions or use certain features,  large volumes of data may have to be exchanged with the backend data centers of the SaaS applications. Transferring data to a public cloud-based SaaS service may compromise security and compliance. Cross-border data transfer issues may also arise.

2.Lack of integration support: Many organizations need extensive integrations with on-premise apps, data and services. SaaS vendors may only offer limited support, which can force organizations to invest on designing and managing integrations internally.

3.Customization: SaaS apps offer very little customization capabilities. This limits users to the features, functionalities, and integrations offered by vendors.

4.Performance and downtime: Since SaaS-based services are vendor controlled, customers have to depend on vendors to maintain servers performance. The possibility of unplanned maintenance activities, cyber attacks, etc. impacting the performance of SaaS apps also remains.

Examples of SaaS

Some of the examples are as follows:

Dropbox

a. Salesforce

b. Cisco WebEx

c. GoToMeeting

PaaS: Platform as a Service

Platform as a Service, also known as cloud platform services, provide cloud components to certain software applications. They deliver the infrastructure developers need to create customized applications. With PaaS, all servers, storage, software development processes, and so on can be managed by a third-party provider, while developers develop, run and maintain the applications.

PaaS Delivery

The delivery model of PaaS is very similar to that of SaaS. The only difference is that PaaS provides a platform for software development instead of delivering software over the internet. This platform is delivered via the web,so developers have the freedom to develop software without worrying about software updates, storage, etc. 

PaaS Advantages

1.Simple and cost effective development and deployment of apps

2.Highly available

3.Scalable

4.Easily customizable without investing too much time in maintaining software

5.Significant reduction in the amount of coding needed

PaaS Characteristics

1.Integrates web services and databases

2.Builds on virtualization technology so resources can be moved based on business requirements

3.A variety of services to assist with app testing, development and deployment

4.Extended customer reach using the same development application

When to use PaaS

1.To optimize the workflow when multiple developers are working on the same project

2.When speed and flexibility are crucial aspects of a  process

3.In order to create customized applications

4.To reduce cost

PaaS Limitations and Concerns

1.Data Security: Using PaaS solutions, organizations can run their own apps. However, the fact that the data is controlled by vendors may pose security risks and raise concerns. 

2.Integrations: The complexity of data stored in data centers has increased. This affects which apps can be adopted with a given PaaS offering. As every component is not built for the cloud, integrating with existing services may be a challenge.

3.Vendor lock-in: If a vendor does not have proper migration policies in place, switching  PaaS solutions without affecting business processes is almost impossible.

4.Customization of legacy systems: Several customization and configuration changes may be required for legacy systems to work with PaaS systems. This may increase complexity as well as cost.

PaaS examples

Some of the most popular PaaS based apps are:

a. Microsoft Windows Azure

b. Google App Engine

c. Open Shift

d. Force.com

IaaS : Infrastructure as a Service

Infrastructure as Service, also known as cloud Infrastructure services, are made up of highly scalable resources.They allow businesses to purchase resources as and when needed instead of buying hardware outright.

IaaS Delivery

IaaS delivers cloud computing infrastructure including servers, networks, storage, etc. through virtualization technology. These servers are provided to organizations through a dashboard or an API, which ensures that  clients have complete control over the entire infrastructure. As opposed to SaaS or PaaS, IaaS clients are responsible for managing applications, OS, middleware, etc. themselves. 

IaaS Advantages

1.It’s the most flexible cloud computing service model

2.Allows businesses to purchase resources as and when needed

3.Highly scalable

4.Offers complete control over the infrastructure

IaaS Characteristics

1.Highly scalable services

2.Cost depends on consumption

3.Resources are available as a service

4.Complete control over infrastructure for organizations

5.Dynamic and flexible

When to use IaaS

1.Startups and small companies may prefer IaaS as they would not want to spend too much money and time on purchasing and creating hardware and software

2.Companies experiencing rapid growth prefer the scalability IaaS offers

3.When companies want complete control over their infrastructure

IaaS Limitations and Concerns

1.Security: Insider threats or system vulnerabilities may expose the data being transmitted between the host infrastructure and virtual machines to unauthorized entities

2.Internal resources and training: Additional resources and training may be required to effectively manage the infrastructure. 

3.Multi tenant security: Hardware resources are dynamically allocated across users, so vendors need to ensure that customers do not get access to each other’s data.

IaaS Examples

a. Amazon Web Services

b. Digital Ocean

c. Microsoft Azure

d. Rackspace