Arbeitspapiere der GMD GMD Technical Report No

Object technology has received considerable attention in the recent years for the integration of various local data sources in a multi-database system (MDBS). An objectoriented data model like ODMG-93 can serve as the canonical data model for the global layer in the MDBS. The ODMG-93 standard defines a closed nested ACID transaction model without intra-transaction parallelism. Although the nested transaction model provides special support for distributed computing environments, the implications of its usage as a global transaction model for MDBS have so far not been examined. In this paper, we present a simple and practical method to implement global nested transaction management for ODMG-compliant multi-database systems. The main contribution of our work is the adaption of the ticket method to achieve global serializability for global nested transactions that conform to ODMG. Our approach is also applicable to OMG's common object request broker architecture. We have succesfully implemented our global nested transaction model within the IRO-DB multi-database system .