RGRAS

RGRAS is a predecessor of GRAS3. It is used as repository in the IPSEN project. The most prominent application of RGRAS is PROGRES a language and environment for graph rewriting systems. RGRAS is as part of the PROGRES release, but also separately as a binary release on its own.

The topmost subsystem of the RGRAS architecture realizes the client server distribution of the system. RGRAS is a multi-client / multi-server system. The following picture shows an example distribution with three clients, two servers, and four graphs handled by the servers. The scenario also shows three clients and as many workstations.



A distribution scenario for RGRAS 

RGRAS is a query-server system, i.e. clients send their queries to the servers and retrieve the results from them. The consequence is that a large number of messages is sent between client and server. To cope with this, RGRAS allows to link client and server functionality into the same operating system process. In the scenario above, client 3 and server 1 could be candidates for this feature, because they run on the same workstation. This technique allows very efficient single-user operation. But additionally, other clients are still able to communicate with the linked server.