1. SaaS Overview
• SaaS differs from Infrastructure and Platform as a Service in that it provides a service that is directly consumable by the end-user. • The most complete cloud computing service model is one in which the computing hardware and software, as well as the solution itself, are provided by a vendor as a complete service offering. It is referred to as the SaaS model.
Eg: Google Gmail, Salesforce.com is the largest SaaS provider of CRM software
• A modern implementation of SaaS using Enterprise Service Bus and architected with SOA components- CC Bible page 73
2. SaaS characteristics
• The software is available over the Internet globally through a browser on demand. • Usage-based and is billed on a recurring basis • The software and the service are monitored and maintained by the vendor, regardless of where all the different software components are running. • Reduced distribution and maintenance costs and minimal end-user system costs generally make SaaS applications cheaper to use than their shrink-wrapped versions. • Such applications feature automated upgrades, updates, and patch management and much faster rollout of changes.
SaaS characteristics
• All users have the same version of the software so each user’s software is compatible with another’s. • SaaS supports multiple users and provides a shared data model through a single-instance, multi-tenancy model. • Salesforce.com v/s Force.com: SaaS v/s PaaS • Salesforce.com is a web application suite that is SaaS, Force.com is Salesforce.com’s PaaS platform for building your own services.
Simple Object Access Protocol (SOAP )
• Building Blocks • A SOAP message is an ordinary XML document containing the following elements:
An Envelope element that identifies the XML document as a SOAP message A Header element that contains header information A Body element that contains call and response information A Fault element containing errors and status information http://www.w3schools.com/soap/soap_syntax.asp
Representational State Transfer (REST)
• REST has emerged as a predominant Web service design model. • REST uses the four HTTP methods GET, POST to execute different operations. • REST-style architectures consist of clients and servers. • Unlike SOAP, REST does not require XML parsing and does not require a message header to and from a service provider • REST is an architectural style for building client-server applications. SOAP is a protocol specification for exchanging data between two endpoints.
Case Study
• http://www.onlinetech.com/resources/casestudies/healthmaster • http://www.mountainmedia.com/SaaS-CaseStudy-c169.html