The CHORCH Approach: How to Model B2Bi Choreographies for Orchestration Execution

The establishment and implementation of cross-organizational business processes is an implication of today’s market pressure for efficiency gains. In this context, BusinessTo-Business integration (B2Bi) focuses on the information integration aspects of business processes. A core task of B2Bi is providing adequate models that capture the message exchanges between integration partners. Following the terminology used in the SOA domain, such models will be called choreographies in the context of this work. Despite the enormous economic importance of B2Bi, existing choreography languages fall short of fulfilling all relevant requirements of B2Bi scenarios. Dedicated B2Bi choreography standards allow for inconsistent outcomes of basic interactions and do not provide unambiguous semantics for advanced interaction models. In contrast to this, more formal or technical choreography languages may provide unambiguous modeling semantics, but do not offer B2Bi domain concepts or an adequate level of abstraction. Defining valid and complete B2Bi choreography models becomes a challenging task in the face of these shortcomings. At the same time, invalid or underspecified choreography definitions are particularly costly considering the organizational setting of B2Bi scenarios. Models are not only needed to bridge the typical gap between business and IT, but also as negotiation means among the business users of the integration partners on the one hand and among the IT experts of the integration partners on the other. Misunderstandings between any two negotiation partners potentially affect the agreements between all other negotiation partners. The CHORCH approach offers tailored support for B2Bi by combining the strengths of both dedicated B2Bi standards and formal rigor. As choreography specification format, the ebXML Business Process Specification Schema (ebBP) standard is used. ebBP provides dedicated B2Bi domain concepts such as so-called BusinessTransactions (BTs) that abstractly specify the exchange of a request business document and an optional response business document. In addition, ebBP provides a format for specifying the sequence of BT executions for capturing complex interaction scenarios. CHORCH improves the offering of ebBP in several ways. Firstly, the execution model of BTs which allows for inconsistent outcomes among the integration partners is redefined such that only consistent outcomes are possible. Secondly, two binary choreography styles are defined as B2Bi implementation contract format in order to streamline implementation projects. Both choreography styles are formalized and provided with a formal execution semantics for ensuring unambiguity. In addition, validity criteria are defined that ensure implementability using BPEL-based orchestrations. Thirdly, the analysis of the synchronization dependencies of complex B2Bi scenarios is supported by means of a multi-party choreography style combined with an analysis framework. This choreography style also is formalized and standard state