Aspect-Orientation to Enhance Web Service Choreographies Using Standards-Based Approaches Abstract Late binding and dynamic composition of Web Services (WS) have long been hailed as one of the great advantages of service-oriented architectures. However, mechanisms to allow developers to achieve such compositions have proved somewhat difficult to provide. Aspect-Oriented Software Development (AOSD) offers means to disentangle cross-cutting concerns from choreographed services, and thereby to achieve flexible choreography. Whereas prior work has used Aspect-aware BPEL engines (involving proprietary language extensions and bespoke execution environments), we present an Aspect-Oriented (AO) method to allow service-implemented aspects to be woven using standard choreography description languages for execution on unmodified platforms. The approach implements aspect logic as WS operations with standard WS interfaces, enabling XSLT to be used for weaving aspect logic into choreography descriptions. It is a novel approach to weaving without committing to a particular execution language and platform, aiming to appeal to users in circumstances where migration to aspect-aware platform is less favourable. The approach is illustrated by an example implementation of an endpoint monitoring system that validates the behaviour of the service against the choreography specification using cross-cutting concerns. The paper concludes by defining a framework within which future developments of this approach can be situated. Short Bio about the Author: Connie Bao, 2nd Year Research student at King's College London, under the supervision of Dr. Nicolas Gold and Prof. Mark Harman.Connie's research interests are Service Oriented Architectures, Aspect Oriented Software Development and Workflow Transformation in the Composite Web Services context. Before joining King's, Connie worked as a Teaching Associate and Industrial Liaison Officer at Dept. of Computing, Imperial College London; and Teaching Assistant at School of Computing, University of Leeds, where she completed her BSc in Computer Science and MSc Information Systems. http://www.dcs.kcl.ac.uk/pg/bao haoying.bao@kcl.ac.uk