The Keene View on Web 2.0, Ajax and SaaS

The Keene View on Web 2.0, Ajax and SaaS
Evaluating SaaS Platforms For ISVs
Here are important criteria for ISVs to consider in evaluating SaaS platforms (sometimes called Platform as a Service, or PaaS):
Open hosting: can I move applications I build to another SaaS hosting providers? Many SaaS platforms lock the ISV into a proprietary hosting provider (e.g., SalesForce). ZDNet says that ISVs need to offer their SaaS software both on demand and on premises.
Full platform: does the SaaS platform offer a complete development solution with presentation layer, business logic, security, database and web services? Some SaaS platforms only offer part of the development stack (e.g., DabbleDB, Tibco GI)
Standard language: does the SaaS platform support development using a standard language such as Java? Many SaaS platforms are based on proprietary languages (e.g., Apex, the proprietary language for SalesForce).