Hanna Eberle

Enabling Adaptation of Pervasive Flows: Built-in Contextual Adaptation

Adaptable pervasive flows are dynamic workflows situated in the real world that modify their execution in order to adapt to changes in the execution environment. This requires on the one hand that a flow must be context-aware and on the other hand that it must be flexible enough to allow an easy and continuous adaptation. In this paper we propose a set of constructs and principles for embedding the adaptation logic within the specification of a flow. Moreover, we show how a standard language for web process modeling (BPEL) can be extended to support the proposed built-in adaptation constructs.

Dynamic Composition of Pervasive Process Fragments

A critical aspect for pervasive computing is the possibility to discover and use process knowledge at run time depending on the specific context. This can be achieved by using an underlying service-based application and exploiting its features in terms of dynamic service discovery, selection, and composition. Pervasive process fragments represent a service-based tool that allows to model incomplete and contextual knowledge. We provide a solution to automatically compose such fragments into complete processes, according to a specific context and specific goals. We compute the solution by encoding process knowledge, domain knowledge and goals into an AI planning problem. We evaluate our approach on different scenarios stress testing the main characteristics of pervasive process fragments.

Process Fragment Composition Operations

The construction kit principle is a well-known software engineering paradigm to foster reusability. In case the construction kit principle is applied at runtime it is even a way to implement flexibility. In today’s workflow technology the construction kit principle is applied, e.g. in in hierarchical modeling approaches using sub processes. In this paper we propose a construction kit application based on process fragment. In contrast to sub processes, process fragments represent on-complete process knowledge, which needs to be integrated with further process knowledge to become a complete process model. Integrating one process fragment with another process fragment requires complex composition operations, since process fragments do not represent the implementation of a single abstract activity like in sub processes, but are knitted together on the same level of granularity. The advantage of process fragments lies in their means to represent noncomplete process knowledge. In this paper we propose a formal process fragment modeling language, which is based on current workflow standard languages, like BPMN. Based on this modeling language we design a basic operation set, which allows to compose process fragments.

Retry scopes to enable robust workflow execution in pervasive environments

Recent workflow languages are designed to serve the needs of business processes running in an unambiguous world based on unambiguous data. In contrast to business processes, processes running in a real world environment have to deal with data uncertainty and instability of the execution environment. Building a workflow language for real world flows based on a workflow language for business processes therefore may need additional modeling elements to be able to deal with this uncertainty and instability. Based on a real world process scenario we analyse and derive requirements for workflow language extensions for real world processes. The contributions provided by this paper are at first to investigate, how a workflow language can be extended properly followed up by the definition of workflow language extensions for real world processes, whereas the extensions are motivated by the real world process scenario. In this paper we use the Business Process Execution Language (BPEL) as extension foundation.

Transactional Process Fragments - Recovery Strategies for Flexible Workflows with Process Fragments

Transactional behavior in workflows was introduced to foster stable and foreseen workflow behavior, even incase a faulting situation occurs. Transactional behavior ensures that a workflow execution obtains a valid business state in the end, whatever faults might happen during execution. Flexibility concepts were introduced to be able to handle unforeseen situations in workflow executions. In this work we present recovery strategies for the flexibility workflow concept of process fragments. Our concept provides means to implement transactional behavior for process fragments, while preserving flexibility. Thereto, we specify two recovery strategies for process fragments: the backward recovery strategy allows to compensate already executed process fragments of the dynamically composed process. The forward recovery strategy handles the occurring faults by executing repair actions.

Enforcement from the Inside: Improving Quality of Business in Process Management

In this paper we introduce a new modeling tool for constraint handling in the area of workflow technology. The constraint handlers can be used to improve the quality of business processes but without changing already existing business logic. Todays workflow languages provide no possibility to model constraints and the actions in case the constraints get violated explicitly. Fault and event handling mechanisms to react to events not expected in normal executions are only provided by the BPEL language. Using BPEL as workflow language we integrate the constraint handling extension without changing any existing semantics in a smart way. In our approach we use this fault and event handling mechanisms to extend the BPEL language with a constraint handling mechanism. By integrating this constraint handling tool into the BPEL language we provide an approach for quality driven process modeling with the BPEL language.

An event-model for constraint-based person-centric flows

Over the past years research in pervasive computing has demonstrated the potential of context-aware and proactive technologies for improving human work performance and to ensure that people act compliant according to predefined regulations. Human work can be structured into tasks, whereas a task is representing an atomic human work entity. A person-centric flow is an IT-representation of the flow of activities an individual person is performing. For example the daily care schedule of a nurse can be understood as the person-centric flow of the nurse. To be able to effectively guide a person in a complex and highly dynamic work environment and to react on possible deviations from the flow the supporting system is required to be aware of the state of the person-centric-flow. Beside guidance the flow information can be utilized to check compliance of a persons flow with prescribed sequences of operation. In this paper we propose a constraint-based workflow model for person-centric flows and an event-model which can be used to inform applications about the state of these flows.