A configurable reference modelling language☆,☆☆
Introduction
Enterprise Systems (ES) offer business solutions for typical functional areas such as procurement, materials management, production, sales and distribution, financial accounting and human resource management [1], [2]. These functions are typically individualized for countries and industries, e.g., automotive, retailing, high-tech. Such off-the-shelf-solutions require configuration before they can be used in the individual context of an organization.
As an approach to improve the understandability of these systems and to stress the process-oriented nature of their solutions, ES vendors have developed application reference models which describe the processes and structure of the system. ES reference models exist in the form of function, data, system organization, object and business process models, although the latter are by far the most popular type.
Current reference models, however, are based on conventional modelling languages that have been developed for the design of enterprise-individual models. Thus, they are not able to adequately depict possible system configurations. Even further, they do not provide decision support regarding the selection of relevant variants. Current application reference models “just” depict the sum of all possible system capabilities and cannot sufficiently deal with the requirement of optionality.
This paper contributes to this area by extending an existing process modelling language used in the by far most successful Enterprise System (SAP) with configurable elements. Thus, it becomes possible to clearly highlight the required decisions which have to be made at build-time, i.e., during the individualization of the generic models.
While our selection of the process modelling language has been driven by its popularity in the relevant ES modelling practice, the proposed extensions can be easily adapted to other modelling techniques (e.g., UML or Petri-Nets). Furthermore, we contribute to the area of ES modelling by providing a comprehensive list of criteria, which have to be satisfied by configurable process modelling languages.
This paper is structured as follows. Section 2 provides an overview of the characteristics of application reference models and gives an example for such a model (the so-called EPC model) and its current shortcomings. Section 3 outlines the research problem and the research methodology. Section 4 lists the requirements for a configurable reference modelling technique. Section 5 first formalizes the notion of Event-Driven Process Chains (EPCs), followed by a presentation of Configurable EPCs (C-EPCs). This paper ends with a section on related work, a brief summary and a discussion of future work.
Section snippets
Reference models
Reference models are generic conceptual models that formalize recommended practices for a certain domain [3], [4], [42]. Often labelled with the term ‘best practice’ reference models claim to capture reusable state-of-the-art practices [5], [6]. The depicted domains can be very different and range from selected functional areas such as financial accounting or Customer Relationship Management to the scope of an entire industry sector, e.g., higher education.
The main objective of reference models
Research problem and research methodology
The existence of reference models highlights a difference from the traditional software development process. Instead of starting from scratch and continuously adding functionality, ES solutions require a continuous narrowing down of the scope of the system. This process starts with the “big picture”, which is then reduced to the relevant part. Reference models can be used as a description of this big picture. It is necessary to select the necessary functions and to decide during the
Requirements for a configurable reference modelling technique
Reference modelling languages have to be configurable. A configurable modelling language is characterized by its capability to support decisions at build time, i.e., the model user can individualize the model by selecting from alternative options before instances will be derived from it. This means that they should not only capture decisions on an instance level, but also on a type level. Unlike decisions on an instance level, i.e., at run-time, decisions on a type level, i.e., at build time,
Configurable Event-Driven Process Chains (C-EPCs)
Before introducing C-EPCs, we first formalize the notion of the classical EPC. Then C-EPCs are introduced and formalized followed by a definition of their semantics and a discussion on partially configured C-EPCs. The section is concluded by some reflections on the requirements stated in the previous section.
Related work
This area of research can be divided into requirements engineering for the development of ES [29], [30] and requirements engineering for the configuration of ES. The latter one is the focus of this paper. Academic contributions in this field are still the exception.
Soffer et al.'s [31] suggestions on ERP modelling can be regarded as the closest to our proposed ideas. The goal of their paper is to determine what language is most appropriate for representing ERP system capabilities. Following the
Conclusion and outlook
Reference models have been defined in this paper as reusable conceptual models that depict recommended structures and processes. One main class of reference models are application reference models that document the functionality of off-the-shelf-solutions. Reference modelling languages face specific requirements regarding the configuration of these models. However, current models such as the SAP reference models (and other ES reference models) are designed using modelling languages that do not
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