Ke-Thia Yao, In-Young Ko, Robert Neches, Robert MacGregor * USC Information Sciences Institute 4676 Admiralty Way, Marina del Rey, CA 90292, U.S.A. {KYao, IKo, RNeches, MacGregor}@isi.edu * Effort sponsored by the Defense Advanced Research Projects Agency (DARPA) and Air Force Research Laboratory, Air Force Materiel Command, USAF, under agreements F30602-00-2-0610. The U.S. Government is authorized to reproduce and distribute reprints for Governmental purposes notwithstanding any copyright annotation thereon. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of the DARPA, the Air Force Research Laboratory, or the U.S. Government. Abstract Assembling software from components is a long-sought vision. However, it is still difficult to insert/replace components in complex software systems and to ensure compatibility. We propose a set of mechanisms that directly address the issues of adaptive composition sensitive to quality concerns. Our approach helps software developers engage in guided, efficient searches and gauge-based evaluations of the set of alternative system implementations that can be built with the components available to them. Our tools support intertwining of composition and manual programming to iteratively build adapters for fitting components into a system when they are functionally satisfactory but suffer interface mismatches. Semantic Interoperability Measures Template Based Assurance of Semantic Interoperability in Software Composition (SIM TBASSCO) helps designers and developers understand the tradeoffs of alternative implementations, and uses records of decisions to generate run-time monitors that warn when the resulting system is being pushed outside its design envelope. 1. INTRODUCTION 1.1 Component Interoperability Problem Assembling software from components is a long- sought vision. However, it is still difficult to insert/replace components in complex software systems and to ensure compatibility. Component frameworks, such as CORBA and DCOM, and Architecture Description Languages (ADLs) help by capturing information at the component interface level that bears on compatibility. But, what they provide is both stricter than necessary and less than sufficient. Current tools focus on exactly matching required vs. available input/output data types and behavior descriptions. This is necessary for plug-compatible substitutions, but too restrictive for adaptation of closely related components. Current approaches capture interface and method specifications, but not implementation factors. This supports composition up to a point, but is not sufficient to address qualitative considerations in composition, such as implementation effort, performance, resource requirements, or reliability. We propose a set of mechanisms that directly address the issues of adaptive composition sensitive to quality concerns. Our approach helps software developers engage in guided, efficient searches and gauge-based evaluations of the set of alternative system implementations that can be built with the components available to them. Our tools support intertwining of composition and manual programming to iteratively build adapters for fitting components into a system when they are functionally satisfactory but suffer interface mismatches. Semantic Interoperability Measures Template Based Assurance of Semantic Interoperability in Software Composition (SIM TBASSCO) helps designers and developers understand the tradeoffs of alternative implementations, and uses records of decisions to generate run-time monitors that warn when the resulting system is pushed beyond its design envelope. 1.2 GeoWorlds Test Bed The system application that we use to test our efforts is GeoWorlds, a component-based information management and analysis system capable of handling both geographic and Web-based information. GeoWorlds combines Geographic Information Systems software with tools for finding, filtering, sorting, characterizing, and analyzing collections of documents accessed via the Web [20, 6, 7, 13, 25]. GeoWorlds is currently in experimental use by the Crisis Operations Planning Team at the US Pacific Command (PACOM), and by the Virtual Information Center, also at US Pacific Command. Example uses at PACOM include: (1) mapping terrorist bombings in the Philippines; (2) locating patterns of recurring natural and technological disasters in China and India; and (3) investigating drug trafficking and piracy in various locales. Semantic Interoperability Scripting and Measurements To appear in the Proceedings of Working Conference on Complex and Dynamic Systems Architecture, December 2001, Brisbane, Australia