He was also a principal research scientist at Honeywell International, Inc., Corporate Technology Center, Bloomington, Minnesota, where he worked on design and implementation of the DDTS (Distributed Database Testbed System) from 1980 to 1982. From 1982 to 1990 he was a faculty member at The University of Houston, Houston, Texas.[3] Since 1990 he has been a faculty member at The University of Texas at Arlington, Arlington, Texas, where he has also been associate chair of the Computer Science and Engineering Department since 2011. Since 2003 he has been a consultant for various law firms, where he has consulted on patent analysis and patent infringement cases and on software copyright infringement cases.[4]