The suit, filed in the U.S. District Court for Northern California, contends that "Google's Android competes with Oracle America's Java as an operating-system software platform for cellular telephones and other mobile devices." Oracle acquired the Java language when it bought Sun Microsystems earlier this year.

'Aware of Sun's Patent Portfolio'

The lawsuit also said the search Relevant Products/Services giant "has been aware of Sun's patent portfolio," and noted that it hired "certain former Sun Java engineers."

Java is used in Google's software development kit (SDK), and Java-built applications are compiled to run in Google's custom virtual machine, Dalvik, using the search giant's custom versions of the compiler and runtime. Java has been attractive to developers in part because Java apps can be written once, and then run on any platform that has the Java virtual machine software.

Another development kit, the Android Native Development Kit, enables third-party developers to build apps in C and C++, although Java has remained the primary development language. The complaint said Android, the Android SDK, and Dalvik violate the seven Oracle patents cited in the lawsuit.

'Quite Disruptive'

Al Hilwa, program director for application development at IDC, noted Google released Android as open source under the Apache open license, which allows other companies to modify it with their own code, although there is liability if any vendor uses protected intellectual property.

He said that it's not clear what part of Google's code is the subject of Oracle's contention of infringement.

"One important piece of code in Android," Hilwa said, "is the Dalvik Java virtual machine, which is based on the Apache Software Foundation's Harmony implementation of Java SE." There has been what Hilwa described as a "long-running feud" with Sun and then Oracle about the certification Relevant Products/Services of Harmony with Sun's Java Test Compatibility Kit, and it isn't known if the alleged infringements also apply to Harmony.

Hilwa said many observers had expected Sun would "raise some hay about Google's fork of the Java code to produce Dalvik," but doing so just as Android is reaching critical mass in the marketplace could "be quite disruptive."

He added that this "typical intellectual-property value defense lawsuit" could have serious repercussions on Android's adoption by OEMs and its growing acceptance by consumers. Hilwa said the suit indicates that Oracle, Sun's new owner, "wants to get into the action and financially leverage its acquired Java assets better."