1 Introduction

The Peer Content Caching and Retrieval: HTTP Extensions Protocol is a set of extensions to the Hypertext Transfer Protocol (HTTP) 1.1 that allows an HTTP/1.1 client and an HTTP/1.1 server to encode content using PeerDist Content Encoding. This encoding enables the client to participate in peer content caching and retrieval. PeerDist Content Encoding is utilized by the Peer Content Caching and Retrieval service framework to allow the client to discover and download content from peer content servers.

The Peer Content Caching and Retrieval Framework is based on a peer-to-peer discovery and distribution model which the peers themselves act as caches from which they serve other requesting peers. The framework also supports the mode of using pre-provisioned hosted caches in place of peer-based caching. The framework is designed to reduce bandwidth consumption on branch-office wide-area-network (WAN) links by having clients retrieve content from distributed caches, when distributed caches are available, rather than from the content servers, which are often located remotely from branch offices over the WAN links. The main benefit of the framework is to reduce operation costs by reducing WAN link utilization, while providing faster downloads from the local area networks (LANs) in the branch offices.

Sections 1.5, 1.8, 1.9, 2, and 3 of this specification are normative. All other sections and examples in this specification are informative.