Failure-Automicity Requirements Usual ACID transactional requirements are too strong/ unimplementable for workflow applications. However,workflows must satisfy some limited transactional properties that guarantee a process is not left in an inconsistent state. Acceptable termination states -every execution of a workflow will terminate in a state that satisfies the failure-atomicity requirements defined by the designer. Committed-objectives of a workflow have been achieved. Aborted-valid termination state in which a workflow has failed to achieve its objectives. A workflow must reach an acceptable termination state even in the presence of system failures. Database System Concepts-6th Edition 26.17 ©Silberschat乜，Korth and Sudarshan
Database System Concepts - 6 26.17 ©Silberschatz, Korth and Sudarshan th Edition Failure-Automicity Requirements Usual ACID transactional requirements are too strong/ unimplementable for workflow applications. However, workflows must satisfy some limited transactional properties that guarantee a process is not left in an inconsistent state. Acceptable termination states - every execution of a workflow will terminate in a state that satisfies the failure-atomicity requirements defined by the designer. Committed - objectives of a workflow have been achieved. Aborted - valid termination state in which a workflow has failed to achieve its objectives. A workflow must reach an acceptable termination state even in the presence of system failures
Execution of Workflows Workflow management systems include: Scheduler-program that process workflows by submitting various tasks for execution,monitoring various events,and evaluation conditions related to intertask dependencies Task agents-control the execution of a task by a processing entity. Mechanism to query to state of the workflow system. Database System Concepts-6th Edition 26.18 @Silberschatz,Korth and Sudarshan
Database System Concepts - 6 26.18 ©Silberschatz, Korth and Sudarshan th Edition Execution of Workflows Workflow management systems include: Scheduler - program that process workflows by submitting various tasks for execution, monitoring various events, and evaluation conditions related to intertask dependencies Task agents - control the execution of a task by a processing entity. Mechanism to query to state of the workflow system