MANILA, Philippines -- Microsoft has been wanting to get cozy lately with open source developers but a top IBM executive warns that the world's largest software maker is not ready to give up full control yet.

Michael O'Rourke, Asia Pacific vice president for IBM Rational, believes that while Microsoft said it would open up APIs (application programming interfaces) of its core products such as Windows and Microsoft Office, the company isn't really "open sourcing" its software.

"This is not at all different from the past. They are not open sourcing these interfaces and not really changing as a platform," O'Rourke said in an interview with INQUIRER.net during a recent visit to Manila for an IBM Rational developer conference.

In essence, what he meant was that while Microsoft is allowing outside developers access to its product APIs, the end goal is to allow open source applications to run on top of Microsoft's platform.

On the other hand, O'Rourke took note of Eclipse, an open source programming platform founded by IBM and later turned into an independent developer community.

"Microsoft is not exactly telling developers that they own the platform," he said. Microsoft of late has been touting its conciliatory stance with the open-source community.

Microsoft Philippines recently announced that the company established an open source lab equipped with its tools to help open source developers test and evaluate their apps on Windows and other products.

IBM, on the other hand, is hyping its Jazz open-source development platform. During the conference, IBM demoed products developed on Jazz, among them Rational Concert, which allows developers from multiple sites to collaborate on a single project.