Azul Systems is suing Sun Microsystems following what it calls litigation threats and unfounded accusations from the giant IT vendor..

The start-up is seeking declaratory relief in its lawsuit because Sun has threatened to sue it for patent infringement and misappropriation of trade secrets.

Azul calls those charges unfounded and said Sun has threatened it with litigation unless Azul agrees to grant Sun partial ownership of the company. Sun also has demanded payment of what Azul describes as "exorbitant" up-front fees and continuing royalties on the sale of Azul products. The company hopes its lawsuit will protect it from those threats.

In turn, Sun said it was surprised by the lawsuit, saying it had granted extra negotiation time to Azul. "Sun has spent over a year trying to achieve a business resolution to Azul's unauthorised use of Sun intellectual property," said Sun spokeswoman Stephanie Von Allmen. "During this period, Azul has repeatedly stonewalled and delayed."

The latest example of this behaviour, Von Allmen wrote, is this lawsuit, and in response Sun has no choice but to countersue to "fully protect and enforce its intellectual property rights."

Azul's software and hardware technology is used for network attached processing, a computing method that unites various resources for applications that use platforms like Sun's Java or Microsoft's .Net. Azul's products tie together "compute pools" that are built from appliances running up to 384 of the company's custom-designed processors. Those appliances deliver powerful processing by supporting a mixed collection of server platforms, operating systems and management tools.

Azul says this approach solves the biggest challenge of data centers: their ability to scale up while controlling costs and providing consistent service. The products are aimed at customers in Fortune 1000 enterprise companies with large-scale Java platforms.

"They're under the assumption we're a derivative technology of Sun, and we know that is not the case," said Stephen DeWitt, president and chief executive officer of Azul Systems. "It's the impact that hydrogen fuel cells would have on the internal combustion engine. They're apples and oranges from a technology perspective but we both deliver processing power resources."

The two companies have enjoyed a decent relationship in the past, since Azul is a licensee of Sun's Java programming language. And DeWitt sold his last company, Cobalt Systems, to Sun in 2001. But the relationship deteriorated when the vendors began to fight over the technology involved in processing systems architecture.

DeWitt said he did not know exactly which aspects Sun had threatened to defend: "We don't know their trade secret claims because they've never shared them with us," he said. Azul's lawsuit lists 20 technologies related to software, processing, and IT architectures, and asks the court to declare that Azul is not infringing those patents.

Azul was founded in April 2002 by Gil Tene, Shyam Pillalamarri and Scott Sellers. The privately held company has 150 employees in the U.S. and 20 developers in Bangalore, India.