InformationWeek reports that Red Hat is being sued for patent infringement by Software Tree. The patent involved is of an impedance-matching layer between an object-oriented system and a relational database. “Red Hat acquired open source developer JBoss in 2006 for $420 million. Software Tree contends that certain of Red Hat’s JBoss products, including the JBoss Enterprise Application Platform, which includes JBoss Hibernate, step on its patent. ‘The infringing products have no substantial noninfringing uses,’ Software Tree says in court papers. The lawsuit also names Dell, Hewlett-Packard, and Genuitec as defendants because the companies sell JBoss-based software or include it on their products.” This is not the first time Red Hat has been sued over JBoss technology. A previous suit was the first public GPL compatible patent settlement and protected not only Red Hat but downstream users and developers as well.