Apparatus method and computer program product for client/server computing with improved transactional interface

A non-legacy server apparatus for use in a client/server computing system for participation in a distributed transaction with a legacy server apparatus, the non-legacy server apparatus has: a non-legacy transactional application participating in a distributed transaction along with a legacy application on a legacy server apparatus; and a non-legacy transaction service which coordinates the distributed transaction and receives transactional calls from the non-legacy transactional application; wherein the non-legacy transaction service includes a mapping layer for directly mapping non-legacy based transactional calls received from the non-legacy transactional application to legacy based transactional calls for transmission to the legacy server apparatus, such that the non-legacy server apparatus does not need to include a legacy transaction service.