Interoperability between PCTE and external database systems - standard transactions and beyond

In order to cope with consistency-preserving operations (i.e. transactions) over distributed and heterogeneous database systems, all database systems involved must support a certain transaction protocol. Unfortunately, the ECMA-PCTE standard does not contain a protocol of this kind. The common protocol for distributed transactions is the two-phase commit. An increasingly accepted industrial standard for distributed transactions covering the two-phase commit is the XA specification by the X/Open group which is supported by most of the UNIX-database vendors. In this paper we propose a concept for an interface that fulfils the XA specification and can be implemented on top of a system conforming to the ECMA-PCTE standard. Recently, more and more (distributed) applications have been based on (transactions on) database systems, e.g. CAD/CAM systems or software engineering environments which are typical PCTE applications. The two-phase commit protocol is not always adequate for all these oft en long-lived kinds of transactions. A great number of non-standard transactions have been suggested to overcome problems like inefficient blocking of data or lack of cooperation between complex activities. However, currently available transaction managers just support the two-phase commit. In the second part of the paper we present a concept for a transaction system whichallows the processing of both standard and non-standard transactions (including nested transactions, SAGAS, split-and-joint transactions, and S-transactions) over different and distributed database systems.