Forrester Research report

SaaS faces major obstacles in four broad sectors of software. They include lower-level elements of the stack, such as operating systems and databases; software for internal IT management and data management; "legacy, entrenched process applications"; and vertical applications, such as a securities transaction processing system, Forrester said.

SaaS is making inroads in mature application areas such as SCM (supply change management), particularly when the customer hasn't already purchased such functionality from an on-premises vendor.

SaaS is starting to shake things up in areas like CRM (customer relationship management) and human resources, where it is replacing on-premises systems.

SaaS is also making some inroads in GRC (governance, risk and compliance) and application development, Forrester added.

SaaS is now the majority model for software sales and delivery in e-purchasing, expense reporting tools and blogging & wiki platforms.

-Cheers