Event-driven Workflow Research Articles

Programming Language Design for Event-Driven Service Composition

To adapt to rapidly changing market conditions and increase the return of investment, today’s IT solutions usually combine service-oriented architecture (SOA) and event-driven architecture (EDA) that support reusability, flexibility, and responsiveness of business processes. Programming languages for development of event-driven service compositions face several main challenges. First, a language should be based on standard service composition languages to be compatible with SOA-enabling technologies. Second, a language should enable seamless integration of services into event-driven workflows. Third, to overcome a knowledge divide, language should enable seamless cooperation between application developers with different skills and knowledge. Since WS-BPEL is widely accepted as standard executable language in SOA, we extended WS-BPEL with support for event-driven workflow coordination. We designed event-handling mechanisms as special-purpose Coopetition services and augmented WS-BPEL with primitives for their invocation. Coopetition services augment SOA with fundamental EDA characteristics: decoupled interactions, many-to-many communication, publish/subscribe messaging, event triggering, and asynchronous operations. To make the application development familiar to wide community of developers, we designed an application-level end-user language on top of WS-BPEL whose primitives for invocation of regular Web services and Coopetition services resemble the constructs of typical scripting and coordination language.

Design and Application of an Intelligent Robotic Gripper for Accurate and Tolerant Electronic Connector Mating

In electronic manufacturing systems, the design of the robotic hand is important for successful accomplishment of the assembly task, and also for human and robot coworker coordinated assembly. Due to the restrictions on the architecture of traditional robotic hands, the status of assembly parts, such as position and rotation during the assembly process cannot be detected effectively. In this research, an intelligent robotic hand – i-Hand, equipped with multiple small sensors – is designed and built for this purpose. Mating connectors by robot, as an experimental case in this paper, is studied to evaluate i-Hand performance. A new model that converts the traditional time-zone-driven model to an event-driven model is proposed to describe the process ofmating connectors, within which, most importantly, the distance between the connector and deformable Printed Circuit Board (PCB) is detected by i-Hand. The generated curve has provided more robust parameters than our previously studied Fault Detection and Diagnosis (FDD) classifier. Various possible situations during assembly are considered and handled based on this event-driven work flow. The effectiveness of our proposed model and algorithm is proven in experiments.

Programming Languages for End-User Personalization of Cyber-Physical Systems

The increased usage of smart devices and appliances opens new venues to build applications that integrate physical and virtual world into consumer-oriented context-sensitive cyber-physical systems (CPS). Since physical processes are dynamic, concurrent, event-driven, and powered by various sensors, controllers, and actuators, a combination of service-oriented architecture (SOA) and event-driven architecture (EDA) is the most promising software architecture for virtualization of heterogeneous components into interoperable application building blocks. In this paper, we propose a CPS design paradigm where devices, such as sensors, controllers, and actuators, are virtualized into environmental services. To support event-driven workflow coordination, we designed special-purpose coopetition services that provide fundamental EDA characteristics, such as decoupled interactions, many-to-many communication, publish/subscribe messaging, event triggering, and asynchronous operations. Based on these two groups of services, we present a design of event-driven service composition languages that target two distinct groups of developers. Using Python as an example, we present a transformation of arbitrary general-purpose programming language into an event-driven service composition language for developers familiar with parallel programming using operating system kernel mechanisms. On the other hand, we present the design and cognitive evaluation of an end-user language, whose 2D tabular workspace resembles the process of sketching an automation application on a sheet of paper.

Programming Language Design for Event-Driven Service Composition

To adapt to rapidly changing market conditions and increase the return of investment, today's IT solutions usually combine service-oriented architecture (SOA) and event-driven architecture (EDA) that support reusability, flexibility, and responsiveness of business processes. Programming languages for development of event-driven service compositions face several main challenges. First, a language should be based on standard service composition languages to be compatible with SOA-enabling technologies. Second, a language should enable seamless integration of services into event-driven workflows. Third, to overcome a knowledge divide, language should enable seamless cooperation between application developers with different skills and knowledge.Since WS-BPEL is widely accepted as standard executable language in SOA, we extended WS-BPEL with support for event-driven workflow coordination. We designed event-handling mechanisms as special-purpose Coopetition services and augmented WS-BPEL with primitives for their invocation. Coopetition services augment SOA with fundamental EDA characteristics: decoupled interactions, many-to-many communication, publish/subscribe messaging, event triggering, and asynchronous operations. To make the application development familiar to wide community of developers, we designed an application-level end-user language on top of WS-BPEL whose primitives for invocation of regular Web services and Coopetition services resemble the constructs of typical scripting and coordination language.

Defining the semantics of reactive components in event-driven workflow execution with event histories

The definition of exact semantics of workflows and involved processing entities is an open yet urgent problem for most systems. This paper considers the semantics and correctness of event-driven workflow execution by reactive components. The basis for the formalization in our approach is provided by an event history which records all the events generated during the execution of workflows by these components. Based on the formal notion of history, it is possible to determine the semantics of workflow systems as the set of event histories they can generate. It also allows to formalize the semantics of reactive components—and consequently, the semantics of workflows—as well as to check whether their observable behavior is correct. In addition to the precise understanding of event-driven workflow execution, the formalized notion of event history also serves as the specification of the workflow execution engine. Ultimately, the semantics of reactive components provides the basis for specifying transformation rules used to map these components onto the execution level.