he Executable Choreography Framework (ECF) aims at increasing the expressiveness and flexibility of cross-domain service composition. Current approaches to service composition tend to sacrifice much expressiveness and flexibility for added control and safety. While safety is a concern that cannot be ignored, today’s service composition approaches enforce unnecessary constraints on the process logic. Processes are made more sequential then they need to be [6].

A major challenge to service composition is enabling truly peer-to-peer crossdomain service collaborations, and deploying them in a competitive time frame, while ensuring the safety of the participants is not compromised. In practice, participant corporate entities are unwilling to adopt mechanisms that allow peer-to-peer service interactions to be deployed when needed.

Domain controllers do not want to execute control flow elements of processes that are initiated and steered by other entities. They want to fully control logic that executes on their domain. Consequently, corporate entities are also reluctant to delegate part of the control flow of their business process. Control delegation is very inflexible. Any change to the process implementation requires a new agreement between controllers to be reached, before the modification can be deployed. As a result, centralized composition approaches are today’s state of the art. A centralized composition engine has immediate control over all message exchanges; all messages transit through the engine.

Tough, distributed compositions are better performing than centralized compositions. Distributed compositions partition the data and control dependencies between the components into smaller components that execute at distributed locations. As demonstrated in [6], decentralized execution brings performance benefits because centralized engines cannot fully take advantage of parallelism. Moreover, advanced service composition scenarios are decentralized by their nature. They do not have a center of control. Centralized composition approaches force the composition model to be tweaked, so that it fits a centralized view of service composition. Decentralized approaches enable the composition implementation to fit the conceptual model of the composition better.

The position of the others is that a better tradeoff between flexibility and expressiveness on the one hand, and control and safety, on the other hand, can be found. Tough, flexible control delegation requires investigating new approaches to composition that go beyond current technologies.

The ECF architecture targets safe dynamic and distributed deployment and refinement of service collaborations.

The paper is structure as follow. Section 2 discusses service orchestration and choreography. Section 3 lists the requirements for executable choreographies, and presents the ECF stack. Section 4 proposes a metamodel for executable choreography, and section 5 discusses the mapping to a Petri net model. Section 6 presents the CASS distributed aspect platform and section 7 discusses dynamic deployment. Section 8 deals with the enforcement of quality rules. Finally, section 9 discusses related work, and section 10 concludes this paper.