题 目：How big is the Web and what does it look like?

报告人：Dr. AndréTrudel

时 间：2012年12月4日(周二)13：30-15：30

地 点：信息学院216学术报告厅

报告摘要：

Exactly how big is the Web? We are interested in the number of publicly accessible web servers. Every device attached to the internet is assigned a unique identifier called an IP address. There are 4.3 billion addresses. In theory, measuring the Web is a trivial problem. We check each IP address for a Web server. In practice though, this is a difficult problem. If we had one computer that ran 24/7 and averaged one IP address per minute, it would take 7,000 years to complete a web census. This amount of time is clearly unreasonable. In the past, researchers used estimation techniques.

We discuss the challenges and results from the WORLD’s first Web census that visits every IP address. When one census terminates, we begin a new one in order to gather historical Web data. The results of each census are stored in a database. The census database allowed us to perform an IP address based study of .com and .net domain names.

If we drew the Web on a single sheet of paper, what would it look like? Note that we needed to use a 9 foot by 9 foot sheet of paper to draw the Web! The picture can be viewed, searched, and explored using our free iPad app.

We consider the geographical distribution of the web servers. The web servers are categorized by country which allows us to view which countries have the most web servers and which have none. We also present other visualizations of the data we have collected.

报告人简介：

André Trudel:

Professor, Computer Science ,Acadia University（加拿大）

Ph.D: Computer Science ,UniversityofWaterloo, 1989

The primary research area is artificial intelligence. A secondary project is measuring the size of the world wide web.