A workflow that is composed of many workflow tasks is the computerized facilitation or automation of a business process, where each workflow task is a logical step or description of a piece of work that contributes toward the accomplishment of a process. A workflow management system gives an integra...
A workflow that is composed of many workflow tasks is the computerized facilitation or automation of a business process, where each workflow task is a logical step or description of a piece of work that contributes toward the accomplishment of a process. A workflow management system gives an integrated execution environment in which workflow processes are completely defined, managed, and executed through completing the roles assigned to workflow activities using the execution of software and human interaction. As the concept of the workflow is widespread and applied to various application areas, new challenges are emerging such as the transaction management and time management in a workflow. To meet these requirements, we propose both a transactional workflow model and a fundamental construct (i.e., workflow critical path identification) of a time-constrained workflow in this thesis. Transactional workflows are workflows supported by an extended transaction model that defines workflow correctness and reliability criteria. Namely, to ensure the correctness and reliability of workflows accessing multiple transactional and/or transactionless objects, each workflow application must be associated with a transaction model that defines the correctness and reliability required by the workflow. Hence, a transactional workflow model involves mapping workflow tasks to constituent transactions within the model, mapping workflow structure to a transaction structure, and guaranteeing that workflow execution follows the correctness criteria defined by the model. There have been many studies on transactions, especially in the areas of database systems, transaction processing monitors, and advanced transaction models. They all, however, have several limitations in applying them to a workflow context. First, they cannot support complex execution flows of a workflow such as parallel, alternative, iterative, and exceptional control structures. Second, previous transaction models assume that all participating resources should be either a support of two phase commit, compensability, or forcibility. But, various non-transactional activities can be included in a workflow process. Finally, a traditional transaction provides the ACID (atomicity, consistency, isolation, durability) properties, which are so strict to long-running workflow processes. Hence, we propose a practical transactional workflow model which is derived from adjusting well-known transaction concepts. We first propose a workflow chart with which various workflow execution flows can be depicted. And then, we propose a method that can specify both failure atomicity and execution atomicity in a workflow chart. Finally, we model the workflow chart using Perti-net and address many analyzable its dynamic properties. The concept of the critical path has been widely discussed in many areas of computer engineering such as parallel and distributed programs, a computer circuit, and a directed acyclic graph. The critical path in a workflow context is defined as a path with the longest average execution time from the start task to the end task of a workflow process. Finding the critical path gives us important information of a workflow process. More than anything else, the critical path may help to identify the workflow bottleneck points. Hence, high performance workflow systems, one of the most outstanding workflow issues, can be achieved by efficient management of the critical path. In workflow resource management, we can improve the overall workflow performance by properly assigning workflow resources to the activities belonging to the critical path. In workflow time management, we can maximize the workflow throughput by efficiently assigning the workflow and task deadlines using the information of the critical path because the path directly affects the total workflow completion time. In this thesis, we first model a workflow process into its corresponding workflow queuing network. And then, we propose a critical path identification method based on the workflow queuing network model. In addition, some experimental results may verify the method`s usefulness.
A workflow that is composed of many workflow tasks is the computerized facilitation or automation of a business process, where each workflow task is a logical step or description of a piece of work that contributes toward the accomplishment of a process. A workflow management system gives an integrated execution environment in which workflow processes are completely defined, managed, and executed through completing the roles assigned to workflow activities using the execution of software and human interaction. As the concept of the workflow is widespread and applied to various application areas, new challenges are emerging such as the transaction management and time management in a workflow. To meet these requirements, we propose both a transactional workflow model and a fundamental construct (i.e., workflow critical path identification) of a time-constrained workflow in this thesis. Transactional workflows are workflows supported by an extended transaction model that defines workflow correctness and reliability criteria. Namely, to ensure the correctness and reliability of workflows accessing multiple transactional and/or transactionless objects, each workflow application must be associated with a transaction model that defines the correctness and reliability required by the workflow. Hence, a transactional workflow model involves mapping workflow tasks to constituent transactions within the model, mapping workflow structure to a transaction structure, and guaranteeing that workflow execution follows the correctness criteria defined by the model. There have been many studies on transactions, especially in the areas of database systems, transaction processing monitors, and advanced transaction models. They all, however, have several limitations in applying them to a workflow context. First, they cannot support complex execution flows of a workflow such as parallel, alternative, iterative, and exceptional control structures. Second, previous transaction models assume that all participating resources should be either a support of two phase commit, compensability, or forcibility. But, various non-transactional activities can be included in a workflow process. Finally, a traditional transaction provides the ACID (atomicity, consistency, isolation, durability) properties, which are so strict to long-running workflow processes. Hence, we propose a practical transactional workflow model which is derived from adjusting well-known transaction concepts. We first propose a workflow chart with which various workflow execution flows can be depicted. And then, we propose a method that can specify both failure atomicity and execution atomicity in a workflow chart. Finally, we model the workflow chart using Perti-net and address many analyzable its dynamic properties. The concept of the critical path has been widely discussed in many areas of computer engineering such as parallel and distributed programs, a computer circuit, and a directed acyclic graph. The critical path in a workflow context is defined as a path with the longest average execution time from the start task to the end task of a workflow process. Finding the critical path gives us important information of a workflow process. More than anything else, the critical path may help to identify the workflow bottleneck points. Hence, high performance workflow systems, one of the most outstanding workflow issues, can be achieved by efficient management of the critical path. In workflow resource management, we can improve the overall workflow performance by properly assigning workflow resources to the activities belonging to the critical path. In workflow time management, we can maximize the workflow throughput by efficiently assigning the workflow and task deadlines using the information of the critical path because the path directly affects the total workflow completion time. In this thesis, we first model a workflow process into its corresponding workflow queuing network. And then, we propose a critical path identification method based on the workflow queuing network model. In addition, some experimental results may verify the method`s usefulness.
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#Workflow Transaction Critical Path 워크플로우 트랜잭션 임계 경로
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