Grid ComputingGrid Computing is a collaboration model. Locally managed resources are virtualized and aggregated in a larger, more capable resource. Grid computing is concerned with coordinating problem solving in virtual organizations and typically is associated with large and complex "Grand Challenge" problems.
In the scientific community, multi-institutional collaboration is required to have any hope of solving fundamental questions as they arise in high-energy physics, fusion or climate research. It is in this community that the world wide web originated to fulfill the need for seamless document access among geographically dispersed team members, and it is also the birthplace of the grid. In 1990 the first HTML communication took place at CERN, and in 1994 the first grid was put together around the Supercomputing conference as a mechanism for all participants to share data and models. It was dubbed I-WAY at that time but it was the starting point of research to try to find solutions for security, resource management, job control, and data caching that are central to grid computing.
Examples are: Terra GRID, Euro GRID
Haas, or Hosting as a ServiceHaaS is a business service model. There are a lot of activities in modern business that are not core operational differentiators. These essential but peripheral services are better outsourced to specialists who can leverage economies of scale. Payroll management, shipping, and web presence are three examples of services that tend to be outsourced for most modern businesss, particularly small and medium sized businesses (SMBs).
Examples are: Startlogic, Hostmonster, Rackspace
SaaS, or Software as a ServiceSaaS is a software deployment model. Application functionality is provided to the user through a web interface and the SaaS provider manages hardware and software operation and maintenance.
Examples: Salesforce.com, Webex, Netsuite
SaaS is generally associated with business software and marketed as a service to lower the cost of internally managed software. SaaS allows customers to lower the initial cost of software licenses and computer hardware to run on.
- Web Site Hosting and Web Application Hosting Services are probably the most ubiquitous instances of the SaaS model
- Customer Resource Management, or CRM, has many different instances, for example Salesforce.com, Siebel, or Coghead
- Completely integrated Enterprise Resource Management systems are provided by SAP, Oracle, Netsuite, Epicor, or Infor
Commercially, SaaS has carved out many different useful services. Unfortunately, this has lead to a fragmentation of the market with the associated interoperability and economic lock-in problems. When selecting a SaaS provider the overriding question should be if you can move your data to other providers or bring it in house. SaaS becomes less interesting at a larger scale or if you want to extract business intelligence from your data. Plan for success but manage for failure. If the SaaS provider does not have a productive mechanism to get all the data out of the service, think twice before signing a contract.
PaaS, or Platform as a ServicePaaS is a software life-cycle model. Applications are developed, tested, deployed, hosted, and maintained on the same integrated platform.
Examples: Bungee Lab Connect, Comrange AppProducer