IBM has rebuffed accusations that it has gone back on a promise not to enforce a group of patents if the technology is used by open-source developers.
In a blog post on Tuesday, open-source software developer Florian Mueller criticised the company for reneging on its five-year-old pledge. He said that IBM is using its patents against a free and open-source (Foss) project called Hercules and a start-up linked to the project called TurboHercules.
IBM acknowledged on Wednesday that it had sent TurboHercules a list of patents it owned on mainframe technology, but said it was "merely responding to TurboHercules' surprise that IBM had intellectual property rights on a platform [it has] been developing for more than 40 years".
The tech giant said that its promise to offer the group of patents royalty-free may not extend to TurboHercules, which is a mainframe emulation development company.
"In 2005, when IBM announced open access to 500 patents that we own, we said the pledge is applicable to qualified open-source individuals or companies," said an IBM spokesperson. "We have serious questions about whether TurboHercules qualifies. TurboHercules is a member of organisations founded and funded by IBM competitors such as Microsoft to attack the mainframe. We have doubts about TurboHercules' motivations."
Mueller, who has accused IBM of hypocrisy over its patent move, told ZDNet UK on Wednesday that the company did not say in 2005 that access to the patents was only open to qualified companies.
"'Qualified' was not in the language of the pledge," said Mueller. "The problem is that 'qualified' becomes an arbitrary and discriminatory decision on their end."
The original terms of the pledge allowed open-source developers and companies to build on IBM-patented technology if they did this under an OSI-approved licence. Hercules was developed under the OSI-approved Q Public License, Mueller said.
TurboHercules filed an antitrust complaint with the European Commission against IBM in March, alleging that the company is preventing customers from using the Hercules mainframe emulator.
Roger Bowler, creator of Hercules and co-founder of TurboHercules, said in a blog post on Tuesday that his company has collaborated with Microsoft as well as with several other companies.
"Bearing in mind that Hercules works very well indeed on both Linux and Windows, not to mention the Macintosh, we are indeed quite happy to cooperate with Microsoft, Hewlett-Packard, Unisys, Dell, Intel, AMD or anyone else who wants to work with us," said Bowler.
Bowler said that the company wanted IBM to agree to allow IBM z/OS mainframe customers to run the operating system on hardware platforms of their choice.