The Research And Implementation Of Task-oriented Chord Agreement

In recent years, with the developing of technology of computer and Internet millions and billions of computer nodes constitute distributed collaborative systems. They can provide the computing power and the resources. In such a large-scale distributed collaborative system, each task that generally can not be done by a node alone needs multiple nodes collaborate to finish. This requires a scalable infrastructure and efficient task coalition formation models to organize resources and computing power to complete the given task. How to use and coordinate these computer nodes to complete our task is an important issue.Large-scale distributed collaborative systems usually have these characteristics: the system has huge number of instability nodes, and it can automatically organize into task coalitions according to the commands. With considering these features, the idea of P2P (Peer to Peer) can be used for infrastructure systems. But traditional P2P mainly locates in the positioning of resources, which is lack of task-oriented features. Therefore, this thesis is trying to use the hierarchical P2P ideology to make task-oriented research.This thesis first introduces the development of the P2P networks and distributed task execution algorithm, analyses the existing P2P technology, and then highlighting the Chord protocol design, related improvements, advantage and disadvantage in task-oriented term. For the inadequacies of current relevant P2P technology in task-oriented, based on the Chord model, this thesis designs a task-oriented Chord system called OT-Chord (Task Oriented Chord). Overall structure, resource discovery, node joining and exiting, stabilization, fault tolerance mechanisms, load balancing are described in detail. Distributed task execution strategy is proposed on the basis of this framework. On the basis of the existing task model, new task model and scheduling methods are proposed which is more suitable for distributed task execution. And the coalition formation algorithm on the large-scale system called DCTE (the Distributed, Clustered Task execution) is described in detail.The OT-Chord architecture have good scalability, supports nodes frequently joining and exiting, not only supports addressing node by id, but also supports addressing node by the resource identifier which is satisfied for the characteristic of task-oriented. And it can avoid the restrictions of firewall or NAT and protects the core network. The task execution strategies in this thesis can minimize negotiation time in the coalition formation, reduces the load on the system, and obtains a higher system throughput.