A Brief History of Web Crawlers

Web crawlers visit internet applications, collect data, and learn about new web pages from visited pages. Web crawlers have a long and interesting history. Early web crawlers collected statistics about the web. In addition to collecting statistics about the web and indexing the applications for search engines, modern crawlers can be used to perform accessibility and vulnerability checks on the application. Quick expansion of the web, and the complexity added to web applications have made the process of crawling a very challenging one. Throughout the history of web crawling many researchers and industrial groups addressed different issues and challenges that web crawlers face. Different solutions have been proposed to reduce the time and cost of crawling. Performing an exhaustive crawl is a challenging question. Additionally capturing the model of a modern web application and extracting data from it automatically is another open question. What follows is a brief history of different technique and algorithms used from the early days of crawling up to the recent days. We introduce criteria to evaluate the relative performance of web crawlers. Based on these criteria we plot the evolution of web crawlers and compare their performanc

Distributed Information Retrieval using Keyword Auctions

This report motivates the need for large-scale distributed approaches to information retrieval, and proposes solutions based on keyword auctions

Downloading Deep Web Data from Real Web Services

Data of deep web in general is stored in a database that is only accessible via web query forms or through web service interfaces. One challenge of deep web crawling is how to select meaningful queries to acquire data. There is substantial research on the selection of queries, such as the approach based on the set covering problem where greedy algorithm or its variation is used. These methods are not extensively studied in the context of real web services, which may impose new challenges for deep web crawling. This thesis studies several query selection methods on Microsoft’s Bing web service, especially the impact of the ranking of the returns in real data sources. Our results show that for unranked data sources, weighted method performed a little better then un-weighted set covering algorithm. For ranked data sources, document frequent estimation is necessary to harvest data more efficiently