"Your data's always yours," Rosenbaum said of Salesforce.com customers, when asked to respond to Ellison's jibes. Salesforce.com also invests heavily in open APIs (application programming interfaces) and other areas meant to give customers flexibility, he added.

But in turn, Force.com provides a "very effective and efficient" platform for developers, Rosenbaum said.

Still, Salesforce.com hasn't depended solely on Force.com, buying Ruby application development vendor Heroku in 2010. Support for Java applications has since been added to Heroku.

Salesforce.com also had an with VMware called VMForce, which focused on Java application development.

The IDG News Service