Creating a Distributed Programming System Using the DSS: A Case Study of OzDSS

This technical report describes the integration of the Distribution Subsystem (DSS) to the programming system Mozart. The result, OzDSS, is described in detail. Essential when coupling a programming system to the DSS is how the internal model of threads and language entities are mapped to the abstract entities of the DSS. The model of threads and language entities of Mozart is described at a detailed level to explain the design choices made when developing the code that couples the DSS to Mozart. To show the challenges associated with different thread implementations, the C++DSS system is introduced. C++DSS is a C++ library which uses the DSS to implement different types of distributed language entities in the form of C++ classes. Mozart emulates threads, thus there is no risk of multiple threads accessing the DSS simultaneously. C++DSS, on the other hand, makes use of POSIX threads, thus simultaneous access to the DSS from multiple POSIX threads can happen. The fundamental differences in how threads are treated in a system that emulates threads (Mozart) to a system that make use of native-threads~(C++DSS) is discussed. The paper is concluded by a performance comparison between the OzDSS system and other distributed programming systems. We see that the OzDSS system outperforms ``industry grade'' Java-RMI and Java-CORBA implementations

An efficient marshaling framework for distributed systems

An efficient (un)marshaling framework is presented. It is designed for distributed applications implemented in languages such as C++. A marshaler/unmarshaler pair converts arbitrary \emph{structured} data between its host and network representations. This technology can also be used for persistent storage. Our framework simplifies the design of efficient and flexible marshalers. The network latency is reduced by concurrent execution of (un)marshaling and network operations. The framework is actually used in Mozart, a distributed programming system that implements Oz, a multi-paradigm concurrent language. Mozart, including the implementation of the framework, is available at http://www.mozart-oz.org