Distributed Monitoring in Large Scale Overlay Networks (OverlayMeter)

针对点对点覆盖网络的质量，研究集中在针对特定使用场景的优化机制。将优化解决方案从一个特定用例转移到另一个用例几乎或不可能实现，因为覆盖图的参数设置和策略选择通常是针对特定用例固定的。覆盖层对环境参数的动态特性(如节点计数或扰动动态)是盲目的，因此不能适应给定的情况。或者，在覆盖中独立且冗余地相互作用的各种机制试图收集相关信息以优化决策。为了使覆盖网络能够以优化的质量服务于广泛的应用领域，我们在本项目中的目标是提供覆盖的信息基础，用于优化覆盖参数设置和策略选择。在该信息基础上，我们考虑关于覆盖的性能的一组统计、关于网络中可用节点的容量的信息以及关于覆盖中的文档的使用统计。未来以质量为中心的覆盖层的创建将通过广泛的可用信息而变得容易。新的覆盖机制将能够假设这些信息的存在，解释它们，并使用它们来优化选择参数设置和策略。在本研究项目中，我们解决了仅使用分散聚集机制来创建覆盖中性能统计的如此广泛的信息基础的挑战。研究、设计和评估了覆盖网络中所有节点或只有部分节点参与测量的高效、精确和安全的测量机制。所研究的机制应该既适用于分布式哈希表，也适用于一般可能包含恶意节点的弱连接覆盖图。除了专注于创建覆盖网络性能的精确全网统计数据外，我们还重点研究了测量机制，以创建对等点容量的全局视图，从而实现基于容量的对等点搜索以及对网络中文档的使用统计和排名。同行能力的强大动力以及要审议的大量文件为衡量这些信息提出了新的挑战。

Aiming at the quality of peer-to-peer overlay networks, research focused on optimized mechanisms for selected usage scenarios. The transfer of optimized solution from one specific use case to another is hardly or impossible to implement, as the parameter setting and strategy selection of the overlay is typically fixed for the specific use case. Either the overlays are blind for the dynamics of the environmental parameters, such as the node count or churn dynamics, and thus cannot adapt to a given situation. Or the various mechanisms that interact in the overlay themselves independently and redundantly try to gather relevant information for optimized decisions. In order to enable overlay networks to serve for a wide range of application areas with optimized quality, we aim in this project at providing of an information basis on the overlay which can be used for optimized overlay parameter settings and strategy selections. We consider in this information basis a set of statistics on the performance of the overlay, information on the capacities of the available nodes in the network as well as usage statistics on the documents in the overlay. The creation of future quality-centric overlays will be eased through the wide set of information available. New overlay mechanisms will be able to assume the existence of these information, interpret them and use them to optimally select parameter settings and strategies.In this research project we address the challenges in the creation of such a broad information basis on performance statistics in the overlay using only decentralized aggregation mechanisms. We investigate, design and evaluate efficient, precise and secure measurement mechanisms for overlay networks for the case that all nodes or only a subset of nodes participate in the measurement. The researched mechanisms should be applicable both on distributed hash tables as well as in general weakly connected overlay graphs which might also contain malicious nodes. Besides the focus on the creation of precise network-wide statistics on the performance of the overlay, we also focus on the research of measurement mechanisms to create a global view on the capacities of the peers in order to enable capacity-based peer search as well as on the usage statistics and rankings on the documents in the network. The strong dynamics of the peer capacities as well as the large number of the documents to be considered define new challenges for the measurement of these information.