Web Site Mirroring Public Home Page

• Introduction
• Current List of Mirrors
• Mirroring Activity Technical Home Page (W3C staff only)
• W3C-LA Mirroring Activity

Introduction

This is the home page of the mirroring activity of the W3C Systems Team. This activity is the continuation of the W3C-LA Mirroring Activity. This page describes the nature and the objectives of the W3C mirroring system in a non-technical way. For technical details, you should go to the Mirroring Activity Technical Home Page (W3C staff only).

The aim of this activity is to spread mirrors of the W3C site around the world. This is not a research topic in order to find a general way to make web mirrors, but a specific development issue taking advantage of all particularities of the W3C web site.

What we call the W3C web mirroring system is a collection of mirrors of the W3C web site around the world, maintained by W3C. Requests for http://www.w3.org/ are served by whichever mirror is closest to the user geographically, using some software developed by W3C staff.

All mirrors are, to a certain extent, linked, and get or give services from or to other mirrors. In this organisation, there are no master servers and no slaves, but only a set of machines serving the same content. However, all mirrors are independent in that they can continue serving information even if they are not in contact with each other.

The features of the W3C mirroring system are :

• Transparency for the users : all mirrors are addressed using the same URL space http://www.w3.org/. The mirroring policy is completly hidden for our customers, and a unique URL will always reach the closest mirror.
• Management of partial mirrors : the W3C web site contains information dedicated to different audiences (roughly Public, Members, Team). According to who is hosting a mirror, only authorized information will be stored on the hosted mirror. However, all requests arriving on a given mirror are served either locally or delegated to another mirror.
• Real-Time update : The content of the W3C web site changes very often. Using classical mirroring techniques, which allow daily or weekly updates, are inadequate. We developed a new technology in order to propagate changes to mirrors as soon as possible, from real-time to one hour delay, according to the way people (W3C staff or collaborators) edit their files.
• Fault Tolerance : based on a neighbouring scheme, a mirror out of synchronisation is able to get in touch with its nearest neighbors in order to give the customer the most up-to-date information.

Current list of mirrors

All W3C mirrors are operated by the W3C Systems Team and a local contact on each site. Users should not use the local Machine Names, but address their access only to www.w3.org.