Toward a Quality-of-Service Framework for Peer-to-Peer Applications

Introduction

P2P networks have traditionally been considered too transient in nature to perform useful computations for real-world applications, leave aside the formulation of a viable QoS framework. The only mature application that P2P networks successfully cater to, are those related to content sharing, where the sheer scale of P2P networks along with strategies for content-caching and replication enable content to be located and downloaded in a time-bound manner. Gummadi et al. (2003), made an early attempt at analyzing the P2P content sharing workloads, quantifying the impact of content locality on query performance and bandwidth savings. Since, then some QoS parameters for P2P applications have been proposed, but they have been limited to content-sharing applications. Specifically, QoS parameters have been proposed for:

• 1.

  Guaranteed content location and retrieval (if it exists) – Query Success

• 2.

  Time-bound content location and retrieval - Query Performance

• 3.

  Correct content retrieval – Content Quality

• 4.

  Video Streaming and Multicasting – Delay, Bandwidth and Jitter

However, the P2P concept has wide applicability in various application domains and the scale and fault-tolerant nature of P2P networks can be exploited to ensure that some useful work gets done even with the transience of participating peers. To quantify the extent of useful work performed and the expected performance a minimal and generic QoS framework needs to be established.

This research paper uses the preliminary experimental results from the implementation of the Peer Enterprises (PE) framework (a cross-organizational peer-to-peer framework encompassing content search, distributed computation, communication, remote storage and services deployment) and uses these experimental results to establish a minimal QoS framework for such P2P applications. Many of the proposed QoS parameters are applicable to P2P applications offering a subset of the features provided by the PE framework.

Background

P2P applications can broadly be classified (Milojicic et al., 2002) into the following categories based on their functionality:

• a.

  Content Distribution

• b.

  Distributed Computation

• c.

  Communication and Collaboration

Table 1 summarizes the application categories, application characteristics and examples of some well-known P2P applications.