Salesforce is developing an e-commerce engine called Force.com Checkout, but for now only "native" applications that are built on its Force.com development platform -- as opposed to ones developed with other tools and then integrated with Salesforce -- can join the pilot program.

Craig Heartwell, chief technology officer of Salesforce partner OnDialog, a maker of marketing software, was irked when a Salesforce representative told him the news, according to a since-removed post on his blog.

"After proving to the world that SaaS can work really well and inspiring a new generation of entrepreneurs to abandon the old software vendor models and become SaaS providers, [Salesforce CEO Marc Benioff] has now decided that the only SaaS that really matters is his SaaS," he wrote. "So he's just been taking advantage of partner companies to build up his own, and he is now abandoning those partners because he wants to be the only player."

Salesforce made its decision because Force.com "wasn't getting enough market traction," Heartwell claimed at another point.

OnDialog integrates its software with Salesforce and is listed on its AppExchange site. Users can browse and test software listed there, but the actual ordering and billing process occurs separately through Salesforce, or its partners, hence the Checkout service.

In a subsequent post, Heartwell tempered his criticisms, stressing that the two companies' business relationship remains intact.

"[Salesforce's] strategy wasn't really a loss of some existing 'thing' as much as a loss of future potential 'things' -- and (in my humble opinion) a negative for customers ... They could have done better by us," he wrote in part.

He did not respond to requests for additional comment.

A Salesforce official adopted a neutral posture in responding to Heartwell's criticism.

"I applaud this partner's passion," said Bruce Francis, vice president of corporate strategy. "The fact that we have passionate partners like this one is a testament to what a great program the AppExchange has been."

There are more than 800 applications on the AppExchange, according to Salesforce. However, Francis could not say how many are natively built: "I don't know if we've added that up and released that number."

As for the Checkout service, Francis stressed that it is still in a pilot phase, but that user feedback is informing the company's decision to admit only native applications for now.

"One thing that customers have been saying is that we want applications built on the same metadata model [as Salesforce and Force.com]," he said.

However, Salesforce hasn't decided whether only native applications will be allowed to use it in the future, he said. "We want to make sure we are responding to the community. We're going to learn from this pilot and learn from our partners. We would be foolish not to listen to what our partners are telling us."