A system for integrated computer software application development and modeling is herein described. The integrated system includes an expert system that can be supplied as a software plug-in to assist a software developer in designing and constructing software applications using uniform modeling language (UML) object modeling. In one embodiment the plug-in works with Rational Software Corporation's Rational Rose modeling product and can be used to develop software applications for use with M3 and the Weblogic family of transaction and application server products from BEA Systems, Inc, and with other third-party software systems.