ترکیب اجرایی مدل های فرآیند کسب و کار با ترکیب قوانین کسب و کار و جریان فرآیند

Emergency of Web services has promoted a new paradigm of a business process which is called the Service-Oriented Business Process (SOBP). The SOBP uses Web services as an implementation platform for activities that belong to a business process, and is modeled with a Business Process Definition Language (BPDL). A de facto standard of BPDLs is the Business Process Execution Language for Web Services (BPEL4WS), but the BPEL4WS requires extra mechanisms to explicitly specify process states in a process model and to separate business rules from process flows. By specifying the states explicitly and separating the business rules, a SOBP gets abilities to rapidly monitor a process in execution time, to efficiently define state-dependent process behavior, to freely change the business rules without modification of the flow, and to firmly guarantee business security by hiding the rules. In order to explicitly specify the process states and to separate the business rules from the process flow, an approach to a state-driven specification of a business process is suggested in this paper. The suggested state-driven approach inserts process states into a process model using process units, and separates the business rules from the process flow by regarding the states as the milestones which indicate where the rules are separated. Because the suggested approach supports a composition of a BPEL4WS executable process by combining the business rules and the process flow, the suggested approach can be used as a complementary design method of a BPEL4WS process model, and not as a substitute method of the BPEL4WS model.

Emergency of Web services has promoted a new paradigm of a business process which is called the Service-Oriented Business Process (SOBP). The SOBP uses Web services as an implementation platform for activities that belong to a business process, and the SOBP can be externalized as Web services (Leymann, Roller, & Schmidt, 2002). The SOBP is modeled with a Business Process Definition Language (BPDL) that composes Web services and defines complex interactions among the Web services. A de facto standard of BPDLs is the Business Process Execution Language for Web Services (BPEL4WS) which defines complex interactions among Web services focusing on the flow of message exchanges. However, the BPEL4WS has two controversial points. First, the BPEL4WS model requires extra mechanisms to explicitly specify process states in a process model because the model is biased toward process flows. Since a process state is process condition at a particular execution time, and if states are explicitly specified in a process model, the progress of a process in execution time can be rapidly monitored based on the states. In addition, process states support to efficiently define state-dependent process behavior such as compensation/fault handling, negotiation, etc. Second, the BPEL4WS model needs additional mechanisms to separate the business rules from the process flow, because the flow and the rules are mixed up in the model. The separation of the business rules from the process flow provides the freedom of changing the rules without modification of the flow and guarantees business security by hiding the rules. In order to explicitly specify the process states and to separate the business rules from the process flow, an approach to a state-driven specification of a business process is suggested in this paper. The suggested state-driven approach inserts the process states into a process model using process units, and separates the business rules from the process flow by regarding the states as the milestones that indicate where the rules are separated. In the state-driven approach, it is suggested that process states should be explicitly specified in a process flow. The process states are explicitly specified using process units composed of an activity and two states that are process conditions before and after execution of the activity, respectively. The process units are connected by assigning a same identity to two process states that each belong to two different process units, and this set of connected process units defines the Abstract Process Flow (APF). Through the process units, therefore, the process states are explicitly specified between activities in the APF. It is also suggested that the business rules should be separated from the process flow. If the suggested definition of the APF is conformed, it is natural that any business rule is not included in the APF. As a result, it can be considered that the business rules are successfully separated from the process flow. But the rules should be combined with the APF to create an execution model, so that the separated business rules are required to recognize the locations where the rules are applied in the APF. In order to recognize the location, the separated business rules generally in the format of 〈if–then–else–〉 should be extended to the format of 〈when–if–then–else–〉. This Extended Business Rule (EBR) includes state information at the 〈when–〉 element which indicates where the business rule is applied. Based on the state information, the EBR provides a foundation of combining the business rules with the APF when an execution model of a SOBP is created. This paper is organized as follows: Section 2 provides a description of related works and Section 3 explains state-driven specification of a SOBP by separating business rules. Section 3.1 overviews the state-driven executable process modeling framework. An explicit specification of process states using process units is discussed in Section 3.2. Section 3.3 explains a separation of the business rules from the APF by extending the rules. Section 3.4 presents a specification of state-dependent process behavior, and a composition of an executable process model by combining the rules, and the flow is shown in Section 3.5. Section 4 discusses some issues on this research and concludes this paper.

Existing BPDLs such as the BPEL4WS and the WSCDL suffer difficulties in specifying process states explicitly and in separating the business rules from the process flow. By specifying states explicitly and separating the business rules, a SOBP gets abilities to rapidly monitor a process in execution time, to efficiently define state-dependent process behavior, to freely change the business rules without modification of the flow, and to firmly guarantee business security by hiding the rules. The suggested approach systematically supports the explicit specification of process states using process units and the separation of the business rules from the process flow using the EBRs. The approach helps the process model handle compensation/faults based on the specification of state-dependent process behavior. In addition, the state-based combination of the EBRs and the APF enables a composition of a BPEL4WS executable process, so that the approach can be used as a complementary design method of the BPEL4WS and not as a substitute method of the BPEL4WS. The approach enhances process flexibility and provides easy understandability and rapid modifiability, because the separation of the EBRs from the APF makes a process model simpler. Based on the enhanced flexibility, the composition time of the process model is expected to be reduced, and the agility of process modification is estimated to be increased. The increased agility provides an ability to cope with rapidly-changing runtime environment of a SOBP. The process robustness in execution time can be also improved as the following strategy. First, as many as possible alternative process fragments are designed between two process states. If multiple alternative fragments are designed, the alternatives branch off at the previous process state. Next, at the previous process state, the EBRs are rapidly modified depending on continuously-changing runtime environment in execution time. Accordingly, the process can be executed more robustly by selecting the most proper alternative fragment except for unavailable alternatives in execution time. Future research works still remain as follows. First, the suggested process model will be formalized based on Abstract State Machine (Börger & Stärk, 2003), Pi-calculus (Milner et al., 1989a and Milner et al., 1989b), or Colored Petri-Net (Kristensen, Christensen, & Jensen, 1998), in order to verify valuable properties of the process model. Second, the process state in the suggested approach will equip ontology-based semantics for the purpose of process interoperability (Lee, Seo, Kang, Kim, & Lee, 2007). Third, a research on the hierarchical compensation/fault management will be also conducted based on the state-driven compensation/fault handling behavior (Lee, Yoon, & Kim, 2004). Finally, the state-driven specification of a SOBP will be supported systematically by the enterprise architecture framework (Kim, Lee, Kim, & Kim, 2006).