Sun shot back at Azul Systems Wednesday, filing a countersuit against the hardware maker in U.S. District Court in San Jose, Calif. In the suit, the computer maker alleged that Azul infringed on six patents and violated trade secrets.

Azul filed for declaratory relief in mid-March, crying foul over what it called "exorbitant" fees and royalties, as well as Sun demanding part ownership in the company. The company alleged that Sun was threatening Azul with legal action for non-compliance.

Sun claims that Azul developed its products on technologies other than its own. "By hiring away key former Sun employees, Azul improperly accessed Sun's technology and plans, which enabled Azul to accelerate introduction of its products to market," the filing reads.

In a statement sent to BetaNews, Azul's lawyer Bob Haslam said Sun's actions were not surprising. He said the company had attempted to negotiate with Sun, however its "belligerent requests" had got the two sides nowhere. He also noted that Sun's original list of allegations was much longer than the suit filed in court Wednesday.

"This leads us to believe that we were right in seeking declaratory relief and we are confident we will prevail," he said. "This suit is not about Azul technology; this suit is about Sun and its predatory attempt to thwart Azul's innovative solution from penetrating the market."

The two companies have close ties. Azul's president and CEO Stephen DeWitt founded Cobalt Networks, which Sun acquired in 2000. Azul's chief marketing officer is Shahin Khan, who formerly was an executive with Sun. The two sides also offer competing applications that act as a central repository to run Java applications.

Sun accuses DeWitt and Khan of using their knowledge of Sun to hire away key employees, who are allegedly working on the identical technology at Azul.