A spat over a manifesto on cloud computing has intensified. One of the drafters of the document has hit back at Microsoft's claim that it had been excluded from discussions andhas been surprised by the company's reaction.

The row started when Microsoft's Steven Martin criticised the manifesto, designed to improve interoperability between cloud vendors in a blog post. Now, Reuven Cohen, founder and chief technologist for Toronto-based cloud-computing startup Enomaly, has responded on his ElasticVapor blog, pointing out that Microsoft had been among the first companies to review the manifesto.

"Let me say, we've been in active discussions with Microsoft about the open cloud manifesto, which has literally come together in the last couple weeks," he wrote. "It is unfortunate they feel this way. ...Their 2:28 a.m. pre-announcement of the manifesto was a complete surprise given our conversations."

Moreover, Cohen challenged Microsoft's contention that the manifesto does not provide for an open forum in which ideas about revisions can be discussed. "If Microsoft is truly committed to an open cloud ecosystem, this document provides a perfect opportunity to publicly state it," he wrote.

Cohen did not name the other companies involved with the manifesto, saying only that "several of the largest technology companies and organisations" are among its co-writers.

However, a document on IBM's website also refers to a manifesto on cloud computing -- this one called an "architectural manifesto" about the "possibilities (and risks) of cloud computing" - hinting that IBM may be one of the large technology companies to which Cohen refers in his post.

Cohen said the goal of the manifesto's authors was to "draft a document that clearly states we ... believe that, like the Internet, the cloud itself should be open."

"The manifesto does not speak to application code or licensing but instead to the fundamental principles that the Internet was founded upon - an open platform available to all," he wrote. "It is a call to action for the worldwide cloud community to get involved and embrace the principles of the open cloud."

In his blog post, Steven Martin had complained about the "lack of openness" of the document, particularly its development process. He claimed that Microsoft had been shown the document and asked to sign it without the opportunity to provide feedback or revisions.