1 Introduction

The Content Caching and Retrieval protocols support content retrieval scenarios such as accessing content from a file or web server. For file access scenarios, this document can be used in conjunction with the File Access Services Protocols Overview [MS-FASOD]. The File Access Services Protocols Overview describes the protocols that are required for network File Access Services interoperation with Windows systems. This document describes the additional protocols, data structures, and mechanisms, such as security, that are required to enable a system of Content Caching and Retrieval to interoperate with Windows systems. The system is designed to support scenarios in which local storage of all possible content at all locations in a distributed network is not practicable, such as in corporate branch offices. If the Content Caching and Retrieval of data is unavailable or fails, normal file access continues without caching by using the SMB 2.1 or 3.x, HTTP, or HTTPS protocols.

Content within the system is divided into segments and blocks, where a block is a subdivision of a segment. Segments and blocks are stored and retrieved by the system, rather than files.

Content caching and retrieval requires at least three computers:

  • One computer to act as a content server (normally located on a wide area network (WAN) link)

  • One to act as a client that is requesting content

  • A third (normally a computer on the same local area network (LAN) as the requesting client) to hold in cache some or all the content that the client computer is requesting