面向迁移实例旅行图动态适应性的目录服务研究*

迁移工作流是一种基于迁移实例在工作位置之间连续迁移并就地利用位置服务执行任务的工作流管理模式，许可的工作位置及迁移顺序由预先规划的旅行图约定。针对一旦工作位置故障或服务发生变化，预先规划的迁移路线就不能实现，从而影响迁移工作流的可靠执行，提出了一种分布式目录服务结构。该结构通过对目录服务组件的设计，不仅支持迁移实例旅行图的静态规划，而且支持基于服务推荐的迁移路线的动态修正，从而大大提高了迁移实例旅行图的动态适应性。

Study of directory services for itinerary dynamic adaptability of migrating instance

Migrating workflow is a workflow management model in which the migrating instance moves among working places continuously and executes tasks by using local services. The permitted working places and the traveling order are determined by the itinerary graph predefined for the migrating instance. If some working places break down or local services are changed then migrating workflow can not be executed reliably because the original traveling path within the itinerary graph can not be formed correctly. To solve above problems, this paper proposed a distributed directory service architecture, which not only supported the static planning of itinerary graph, but also supported the dynamic revising of traveling path by recommendation of working place for migrating instance to update the traveling path. The example demonstrats that the directory service components can greatly enhance the dynamic adaptability of itinerary for migrating instance.