A popular architecture for enterprise applications is one of a stateless object-based server accessing persistent data through object-relational mapping software. The reported benefits of using object-relational mapping software are increased developer productivity, greater database portability and improved runtime performance over hand-written SQL due to caching. In spite of these supposed benefits, many software architects are suspicious of the "black box" nature of O-R mapping software. Discerning how O-R mapping software actually accesses a database is difficult. The testbed of object relational products for enterprise distributed objects (TORPEDO) is designed to reveal the sophistication of O-R mapping software in accessing databases in single server and clustered environments. TORPEDO defines a set of realistic application level operations that detect a significant set of database access optimizations. TORPEDO supports two standard Java APIs for O-R mapping, namely, container managed persistence (CMP 2.0) and Java data objects (JDO). TORPEDO also supports the TopLink and Hibernate APIs. There are dozens of commercial and open-source O-R mapping products supporting these APIs. Results from running TORPEDO on different O-R mapping systems are comparable. We provide sample results from running TORPEDO on popular O-R mapping solutions. We describe why the optimizations TORPEDO reveals are important and how the application level operations detect the optimizations.

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The Gemini system is a replicated file system test-bed designed for local area networks and is built using ordinary host UNIX machines. Gemini was designed as a means to empirically test consistency and recovery schemes for replicated files in a distributed environment. A principle objective is to protect files against a fixed number of host and network failures while maintaining consistent data. Gemini replicated files are implemented as several copies of ordinary files that reside on distinct hosts. We present the Gemini system test-bed design and discuss three consistency and recovery schemes: voting with witnesses, dynamic voting, and semi-synchronous control. Empirical and analytic performance results are presented.