Cloud Service Models - SaaS, PaaS, IaaS

Cloud Service Models

• Cloud Software as a Service (SaaS)
• Cloud Platform as a Service (PaaS)
• Cloud Infrastructure as a Service (IaaS)

Software as a Service (SaaS)

• SaaS is a licensed software offering on the cloud and pay per use
• SaaS is a software delivery methodology that provides licensed multi-tenant access to
• Software and its functions remotely as a Web-based service. Usually billed based on usage
• Usually multi tenant environment
• Highly scalable architecture
• Customers do not invest on software application programs
• The capability provided to the consumer is to use the provider’s applications running on a cloud infrastructure.
• The applications are accessible from various client devices through a thin client interface such as a web browser (e.g., web-based email).
• The consumer does not manage or control the underlying cloud infrastructure including network, servers, operating systems, storage, data or even individual application capabilities, with the possible exception of limited user specific application configuration settings.

SaaS providers

• Google’s Gmail, Docs, Talk etc
• Microsoft’s Hotmail, Sharepoint
• SalesForce,
• Yahoo, Facebook

Infrastructure as a Service (IaaS)

• IaaS is the delivery of technology infrastructure ( mostly hardware) as an on demand, scalable service
• Usually billed based on usage
• Usually multi tenant virtualized environment
• Can be coupled with Managed Services for OS and application support
• User can choose his OS, storage, deployed app, networking components
• The capability provided to the consumer is to provision processing, storage, networks, and other fundamental computing resources.
• Consumer is able to deploy and run arbitrary software, which may include operating systems and applications.
• The consumer does not manage or control the underlying cloud infrastructure but has control over operating systems, storage, deployed applications, and possibly limited control of select networking components (e.g., host firewalls).

IaaS providers

• Amazon Elastic Compute Cloud (EC2)
• Each instance provides 1-20 processors, upto 16 GB RAM, 1.69TB storage
• RackSpace Hosting
• Each instance provides 4 core CPU, upto 8 GB RAM, 480 GB storage
• Joyent Cloud
• Each instance provides 8 CPUs, upto 32 GB RAM, 48 GB storage
• Go Grid
• Each instance provides 1-6 processors, up to 15 GB RAM, 1.69TB storage

Platform as a Service (PaaS)

• PaaS provides all of the facilities required to support the complete life cycle of building,
• delivering, and deploying web applications and services entirely from the Internet. Typically applications must be developed with a particular platform in mind
• Multi-tenant environments
• Highly scalable multi tier architecture
• The capability provided to the consumer is to deploy onto the cloud infrastructure consumer-created or acquired applications created using programming languages and
• tools supported by the provider.
• The consumer does not manage or control the underlying cloud infrastructure including
• network, servers, operating systems, or storage, but has control over the deployed applications and possibly application hosting environment configurations.

PaaS providers

• Google App Engine
• Python, Java, Eclipse
• Microsoft Azure
• .Net, Visual Studio
• SalesForce
• Apex, Web wizard
• TIBCO,
• VMware,
• Zoho