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Web service choreography describes protocols for multiparty collaboration, whereas orchestration focuses on single peers. One key requirement of choreography is to support transactions, which makes exceptional handling and finalization very important features in modelling choreography. A projection is a procedure which takes a choreography and generates a set of processes in the orchestration level. Given a choreography, how to project exceptional handling and finalization constructs is still an open problem. This paper aims to study exception handling and transactionality in choreographies from a projection view. We propose formal languages for both choreography and orchestration with trace semantics, and a projection based on the relationship between choreography and scope rooted in WS-CDL and WS-BPEL respectively. [ABSTRACT FROM AUTHOR]

The Web Services Choreography Description Language (WS-CDL) is a W3C specification for the description of peer-to-peer collaborations of participants from a global viewpoint. For the rigorous development and tools support for the language, the formal semantics of WS-CDL is worth investigating. This paper proposes a small language CDL as a formal model of the simplified WS-CDL, which includes important concepts related to participant roles and collaborations among them in a choreography. The formal operational semantics of CDL is given. Based on the formal model, we discuss further: 1) project a given choreography to orchestration views, which provides a basis for the implementation of the choreography by code generation; 2) translate WS-CDL to the input language of the model-checker SPIN, which allows us to automatically verify the correctness of a given choreography. An automatic translator has been implemented. [ABSTRACT FROM AUTHOR]