Oliver Kopp

BPEL4Chor: Extending BPEL for Modeling Choreographies

The business process execution language (BPEL) is a language to orchestrate web services into a single business process. In a choreography view, several processes are interconnected and their interaction behavior is described from a global perspective. This paper shows how BPEL can be extended for defining choreographies. The proposed extensions (BPEL4Chor) distinguish between three aspects: (i) participant behavior descriptions, i.e. control flow dependencies in each participant, (ii) the participant topology, i.e. the existing participants and their interconnection using message links and (iii) participant groundings, i.e. concrete configurations for data formats and port types. As BPEL itself is used unchanged, the extensions facilitate a seamless integration between service choreographies and orchestrations. The suitability of the extensions is validated by assessing their support for the Service Interaction Patterns.

OpenTOSCA --- A Runtime for TOSCA-Based Cloud Applications

TOSCA is a new standard facilitating platform independent description of Cloud applications. OpenTOSCA is a runtime for TOSCA-based Cloud applications. The runtime enables fully automated plan-based deployment and management of applications defined in the OASIS TOSCA packaging format CSAR. This paper outlines the core concepts of TOSCA and provides a system overview on OpenTOSCA by describing its modular and extensible architecture, as well as presenting our prototypical implementation. We demonstrate the use of OpenTOSCA by deploying and instantiating the school management and learning application Moodle.

TOSCA: Portable Automated Deployment and Management of Cloud Applications

Portability and automated management of composite applications are major concerns of today’s enterprise IT. These applications typically consist of heterogeneous distributed components combined to provide the application’s functionality. This architectural style challenges the operation and management of the application as a whole and requires new concepts for deployment, configuration, operation, and termination. The upcoming OASIS Topology and Orchestration Specification for Cloud Applications (TOSCA) standard provides new ways to enable portable automated deployment and management of composite applications. TOSCA describes the structure of composite applications as topologies containing their components and their relationships. Plans capture management tasks by orchestrating management operations exposed by the components.This chapter provides an overview on the concepts and usage of TOSCA.

Interacting services: From specification to execution

Interacting services play a key role to realize business process integration among different business partners by means of electronic message exchange. In order to provide seamless integration of these services, the messages exchanged as well as their dependencies must be well-defined. Service choreographies are a means to describe the allowed conversations. This article presents a requirements framework for service choreography languages, along which existing choreography languages are assessed. The requirements framework provides the basis for introducing the language BPEL4Chor, which extends the industry standard WS-BPEL with choreography-specific concepts. A validation is provided and integration with executable service orchestrations is discussed.

Winery --- A Modeling Tool for TOSCA-Based Cloud Applications

TOSCA is a new OASIS standard to describe composite applications and their management. The structure of an application is described by a topology, whereas management plans describe the applications management functionalities, e.g., provisioning or migration. Winery is a tool offering an HTML5-based environment for graph-based modeling of application topologies and defining reusable component and relationship types. Thereby, it uses TOSCA as internal storage, import, and export format. This demonstration shows how Winery supports modeling of TOSCA-based applications. We use the school management software Moodle as running example throughout the paper.

Analyzing BPEL4Chor: verification and participant synthesis

Choreographies offer means to capture global interactions between business processes of different partners. BPEL4Chor has been introduced to describe these interactions using BPEL. Currently, there are no formal methods available to verify BPEL4Chor choreographies. In this paper, we present how BPEL4Chor choreographies can be verified using Petri nets. A case study undermines that our verification techniques scale. Additionally, we show how the verification techniques can be used to generate a stub process for a partner taking part in a choreography. This is especially useful when the behavior of one participant is intended to follow the corresponding requirements of the other participants. Thus, the missing participant behavior can be generated and the error-prone design of that participant can be skipped.

Cross-organizational process monitoring based on service choreographies

Business process monitoring in the area of service oriented computing is typically performed using business activity monitoring technology in an intra-organizational setting. Due to outsourcing and the increasing need for companies to work together to meet their joint customer demands, there is a need for monitoring of business processes across organizational boundaries. Thereby, partners in a choreography have to exchange monitoring data, in order to enable process tracking and evaluation of process metrics. In this paper, we describe an event-based monitoring approach based on BPEL4Chor service choreography descriptions. We show how to define monitoring agreements specifying events each partner in the choreography has to provide. We distinguish between resource events and complex events for calculation of process metrics using complex event processing technology. We present our implementation and evaluate the concepts based on a scenario.

The Difference Between Graph-Based and Block-Structured Business Process Modelling Languages

The most prominent business process notations in use today are BPMN, EPC and BPEL. While all those languages show similarities on the conceptual level and share similar constructs, the semantics of these constructs and even the intended use of the language itself are often quite different. As a result, users are uncertain when to use which language or construct in a particular language, especially when they have used another business process notation before. In this paper, we discuss the core characteristics of graph-based and block-structured modelling languages and compare them with respect to their join and loop semantics.

Combining Declarative and Imperative Cloud Application Provisioning Based on TOSCA

The automation of application provisioning is one of the most important issues in Cloud Computing. The Topology and Orchestration Specification for Cloud Applications (TOSCA) supports automating provisioning by two different flavors: (i) declarative processing is based on interpreting application topology models by a runtime that infers provisioning logic whereas (ii) imperative processing employs provisioning plans that explicitly describe the provisioning tasks to be executed. Both flavors come with benefits and drawbacks. This paper presents a means to combine both flavors to resolve drawbacks and to profit from benefits of both worlds: we propose a standards-based approach to generate provisioning plans based on TOSCA topology models. These provisioning plans are workflows that can be executed fully automatically and may be customized by application developers after generation. We prove the technical feasibility of the approach by an end-to-end open source toolchain and evaluate its extensibility, performance, and complexity.

Vino4TOSCA: A Visual Notation for Application Topologies Based on TOSCA

A major difficulty in enterprise computing is the modeling of complex application topologies consisting of numerous individual components and their relationships. Especially in the context of cloud computing, the Topology and Orchestration Specification for Cloud Applications (TOSCA) has been proposed recently for standardization to tackle this issue. However, TOSCA currently lacks a well-defined visual notation enabling effective and efficient communication in order to transport the semantics of the encoded information to human beings. In this paper, we propose a visual notation for TOSCA based on established usability research which provides additional concepts for visual modularization and abstraction of large application topologies.