论文标题:基于数据库表示的工作流模型
论文作者
论文导师 杨莉,论文学位 硕士,论文专业 计算机应用
论文单位 中国科学院研究生院（计算技术研究所）,点击次数 307,论文页数 67页File Size1958K
1999-05-01论文网 http://www.lw23.com/lunwen_363907/
Workflow; Database; Workflow Management System; Workflow Definition; Workflow Engine; Workflow Server
目前，不下百种的商用工作流管理系统业已问世，但在这些系统中仍存在着某些不足之处，例如，难于支持大规模应用场景中庞大的并发用户数量和进程数量，难以满足系统备份恢复以及可用性、可扩展性、鲁棒性等诸多性能方面的需求。但是，作为工作流管理系统中不可或缺的支撑平台——数据库，对这类问题却都已经有了比较成熟的解决方案。因此，一种基于数据库表示来设计实现工作流的想法便产生了。 所谓“基于数据库表示”是指整个工作流管理系统的重心与基础为数据库，其中不仅流程定义、流程实例数据等信息都存储于数据库中，而且工作流引擎也可直接利用数据库提供的过程化SQL实现。 基于数据库表示的工作流模型不仅结构简单、易于实现，具有极强的流程表达能力、灵活的流程配置能力、强大的任务分配机制，而且更重要的是可以直接利用大型数据库中已经实现了的各种功能与特性：大规模用户与进程的并发执行、数据备份与恢复、故障检测、安全机制、系统的稳定性、事务模型等方面的支持。因此，采用这种模型，既可减低工作流服务器设计的复杂度，又可提高其性能。
There are hundred commercial workflow products in the market nowadays, howerver the weakness or limitation of these system still exists. For example, when they are used in the large scale environment, they can hardly support large amount of users and processes running concurrently, or they lack of mechanism for backup and efficient recovery, availability, scalability, robustness. On the other hand, database, which is an important relevant technology, has already solved this kind of problem. Therefore, the idea of using database representation to design and realize workflow came into mind."Based on database representation" means that database is the centric and fundamental part of the workflow management system, where not only process definition, process instances are stored in the database, but the workflow engine can be developed directly by using the procedure SQL language as well.The architecture of the workflow model based on database representation is very simple, easy to implemente, expressive enough to define complex processes, and has the ability of dynamic process reconfiguration, flexible task assignment. Moreover this model inherit the functionalities and properties of large scale database management systems : the support of large amount of concurrent users and processes, backup and recovery function, failure detection, security mechanism, system robustness, transaction model etc. In a word, this model can simplify the design of workflow server, while improve the performance of it.
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