Post-facto integration technology: new discipline for an old practice

Experience in building major pieces of a software development platform by integrating existing software components into a uniform programming environment is reported. These components are written in incompatible languages and follow idiosyncratic protocols and conventions. These are examples of a common software engineering practice called post-facto integration. In this style of integration, the integrated system is designed after its major subcomponents have been built, often for a rather different purpose. A research effort has been initiated to better understand this style of integration and to develop tools and methods to make it a more productive and reliable software engineering practice. Two models for post-facto integration have been identified, one for tools integration and one for information integration. A model is proposed for post-facto tool integration which is based on a module interconnection language for loosely coupled, communication processes where existing tools are encapsulated as concurrent objects