Transparent Remote Access

In distributed systems, the different processors communicate via network messages. Object oriented systems do not focus on these messages, but on the responsibilities each object fulfils. Between the top-level objects it should be invisible on which system an addressed object resides. The Transparent Remote Access pattern gives a recipe how the implementation of a method can defer the invocation to another processor. To support Transparent Remote Access even on small machines, a stepwise approach is introduced that allows for simplification when only a part of the functionality is needed. Pattern : Transparent Remote Access An application is distributed among multiple processes or processors. It is developed using object-oriented techniques and a responsibility based approach. You are prepared to use a Protocol-Follows-Application Design [Marquardt] process. How can you hide your distribution mechanisms and message handling from both the caller and the called implementation? • Domain class users must not know or see the transport facilities or depend on them. • Different classes must have clearly separated responsibilities. • The application evolves and may need more remotely addressed objects in the future. • Development is most efficient when the desired solution is easy to understand and apply. • Development of additional classes causes effort and time. • Addressing functionality remotely comes with performance degradation. Implement technical objects around each object that you need to access remotely. Use Proxies [GOF] to convert a method call into a transport message; use Forwarder-Receiver [POSA] to send this message to the processor that hosts the implementation; use a Reactor [POSA2] to address the appropriate implementation. An infrastructure for message transportation, multiplexing, and interpretation is required. On this infrastructure, application specific classes are build. Each domain class is split in several classes with different responsibilities. The interface is separated from the implementation; the Klaus Marquardt Käthe-Kollwitz-Weg 14, D-23558 Lübeck, Germany Email: [email protected]