Carsten Hentrich

Modeling process-driven and service-oriented architectures using patterns and pattern primitives

Service-oriented architectures are increasingly used in the context of business processes. However, the proven practices for process-oriented integration of services are not well documented yet. In addition, modeling approaches for the integration of processes and services are neither mature nor do they exactly reflect the proven practices. In this article, we propose a pattern language for process-oriented integration of services to describe the proven practices. Our main contribution is a modeling concept based on pattern primitives for these patterns. A pattern primitive is a fundamental, precisely specified modeling element that represents a pattern. We present a catalog of pattern primitives that are precisely modeled using OCL constraints and map these primitives to the patterns in the pattern language of process-oriented integration of services. We also present a model validation tool that we have developed to support modeling the process-oriented integration of services, and an industrial case study in which we have applied our results.

Patterns for business object model integration in process-driven and service-oriented architectures

Service-oriented architectures often have the goal to integrate various systems of one or more organizations in a flexible way to be able to quickly react on business changes. Integration based only on services, however, falls short in reaching this goal because the application-specific business object models of multiple external systems (especially legacy systems) need to be integrated into the service-oriented system. When multiple business object models must be integrated into one system, serious data integration issues might arise. Examples of such problems are incompatible data definitions, inconsistent data across the enterprise, data redundancy, and update anomalies. We present patterns that address these issues and describe how to integrate the application-specific business object models of various external systems into a consistent process-driven and service-oriented architecture.

Architecting as decision making with patterns and primitives

The application of patterns is used as a foundation for many central design decisions in software architecture, but because of the informal nature of patterns, these design decisions are usually not precisely documented in the models. In our earlier work, we had proposed pattern primitives as a solution to precisely model the patterns in the corresponding architectural views. Building upon that approach, this paper introduces a pattern-based architecting process that aims at inexpensively documenting design decisions in the architectural views alongside the natural flow of design. The decisions that are made explicit, concern the selection of patterns, their variants and the corresponding primitives, as well as the resolution of inconsistencies between the architectural views. The approach is demonstrated in the domain of process-driven SOA for two architectural views: Component-and-Connector and Process Flow.

A pattern language for process execution and integration design in service-oriented architectures

Process-driven SOAs are using processes to orchestrate services. Designing a non-trivial process-driven SOA involves many difficult design and architectural decisions. Examples are: Different kinds of processes exist: long-running, business-oriented and short-running, technical processes. How to best integrate them and how to map them to execution platforms? A SOA has many different stakeholders, such as business analysts, management, software designers, architects, and developers, as well as many different types of models these stakeholders need to work with. How to present each of them with the best view on the models they need for their work? A realistic process-driven SOA contains many systems that need to be integrated, such as various process engines, services, and backend systems, running on heterogeneous technologies and platforms. How to perform integration in a way that is maintainable and scalable? This article introduces a pattern language that deals with process modeling, execution, and integration. Its main goal is to help solution architects, as well as process and service designers, to master the challenges in designing a stable and evolvable process-driven SOA.

An approach for pattern mining through grounded theory techniques and its applications to process-driven SOA patterns

Pattern mining is a term used in the pattern community to describe the process of identifying or discovering patterns. To identify new patterns, usually an informal or ad hoc process of finding patterns (e.g., in existing software systems) is used. This paper reflects on lessons learned and methods used regarding the integration of software pattern mining with qualitative research methods during our work on a pattern language for process-driven and service-oriented architectures (SOAs). This pattern language aims at closing the conceptual gap between business architecture and software architecture with a focus on process-driven solutions. In this paper we emphasize the notion of understanding patterns as sociological phenomena of problem solving behavior. We further introduce a systematic approach for pattern mining based Glaserian Grounded Theory techniques. This approach has been applied for mining the pattern language for process-driven SOAs. This work may also contribute to a better empirical grounding of software pattern mining. We will illustrate our approach using the pattern language for process-driven SOAs as a pattern mining case study.

Capability-based service identification in service-oriented legacy modernization

Moving from a heterogeneous IT landscape with a set of legacy applications to a more flexible SOA-based architecture is a major strategic concern for many large organizations. Key drivers are to build a robust, easy-to-maintain and cost-efficient architecture. Service identification is a key task in this context, and it must cope with the inherent complexity of existing IT systems and their constant evolution. In this paper we describe the CAPABILITY-BASED SERVICE pattern that identifies services and defines the service model based on a model of business capabilities. Business capabilities describe what an enterprise does, not how something is done in the enterprise. Service identification based on business capabilities is an alternative to process-based service identification, especially useful in cases where process modeling is not feasible, for instance, because of budget or time limitations or where processes are not stable enough over time.

Synchronization patterns for process-driven and service-oriented architectures

This paper introduces a small pattern language for solving different kinds of synchronization problems in the area of process-driven and service-oriented architectures. The paper addresses synchronization issues in terms of coordinating the order of actions in technically independent process instances. Synchronization is thus addressed in terms of event-, control flow-, and object access synchronization. The patterns are related to the Service Composition and Service Provider Layers in an SOA.

Pattern-based process for a legacy to SOA modernization roadmap

Many organizations still operate their businessms which cause high maintenance costs and are difficult to change. After the hype about service-oriented architectures (SOAs) was gone, they were implemented successfully and helped replacing old legacy systems with flexible services, for example at large companies in the finance or logistics industry. While recent research and the pattern literature cover the technical aspects of SOA and the alignment between business and IT, defining and planning a roadmap for a SOA modernization program, which is essential for initiating such a program and getting the necessary commitment, has not been in the focus of research yet. Thus, we propose a design process for the definition of a high-level roadmap. It considers determining architectural decisions and planning decisions by selecting appropriate patterns and reference architectures. Furthermore we define a heuristic for the roadmap planning activities, because we see a lack of appropriate planning patterns. A case study explains how the roadmap design process has been applied in a large-scale industry project concerning a SOA modernization program of a global logistics provider. The pattern-based process should motivate pursuing further research about roadmap design processes and patterns and provide guidance for industry experts.

Specific Drivers for SOA in E-government: Challenges and Solutions

Long term influences like EU law and demographic changes can already be observed as important drivers for change in European governments. Those influences shape how governmental institutions provide their services, how they operate internally and with each other; even across national boundaries and according to international European regulations. The IT of governmental institutions needs to deal with these long term influences. SOA as a strategy is a possible way to deal with these changing circumstances. We illustrate how those different influences drive changes towards SOA in governmental institutions in Germany. In this context, the specific challanges of SOA in e-Government will be highlighted according to examples from Germany. We will elaborate on how SOA can be a means for those long term goals while providing the necessary stable strategy in a likely dynamic political environment.