Complex, large scale software systems are typically assembled from many software components and subsystems, designed and developed in a distributed fashion by multiple teams, each addressing a particular set of concerns. Some of these components can be legacy systems which are now being reused, often with some degree of modification. Other components can be specifically developed for the new system, and yet others may be general purpose off-the-shelf (OTS) components, military or commercial (MOTS or COTS), acquired from external software manufacturers. The assembly of these system components is typically done in one of the last stages of the development process – the system integration phase. Problems found late in software development are often disproportionately costly both in terms of time and money. Increasingly, model based development (MBD) is being employed not only to simplify and better manage the development process, but also to facilitate analyses of the target system early in development where uncovering potential faults in system design is substantially less expensive.