Intelligent Crawling and Indexingusing Lucene By Shiva Thatipelli Mohammad Zubair (Advisor)
Contents Searching Indexing Lucene Indexing with Lucene Indexing Static and Dynamic Pages Extracting and Indexing Dynamic Pages Implementation Screens
Searching Looking up words in an index Factors Affecting Search Precision – How well the system can filter Speed Single, Multiple Phase queries, Results ranking, Sorting, Wild card queries, Range queries support
Indexing Sequential Search is bad (Not Scalable) Index speeds up selection Index is a special data structure which allows rapid searching. Different Index Implementations - B Trees - Hash Map
Search Process QueryDocs Docs Indexing API Hits Index
Lucene High-performance, full-featured text search engine library Written 100% in pure java Easy to use yet powerful API Jakarta Apache Product. Strong open source community support.
Why Lucene? Open source (Not proprietary) Easy to use, good documentation Interoperable - ex: Index generated by java can be used by VB, asp, perl application Powerful And Highly Scalable Index Format Designed for interoperability Well Documented Resides on File System, RAM, custom store
Continued Algorithms Efficient, fast and optimized• Incremental Indexing• Boolean Query, Fuzzy Query, Range Query, Multi Phrase Query, Wild Card Query etc…• Content Tagging – Documents as Collection of terms Heterogeneous documents - Useful when different set of metadata present for different mime types
Indexing With Lucene What type of documents can be indexed? Any document from which text can be fetched and extracted over the net with a URL Uses Inverted Index - The index stores statistics about terms in order to make term-based search more efficient.
Indexing With Lucene Contd… HTML XLS WORD PDF extracted extracted extracted extracted Parser Parser Parser Parser Analyzer Index
Indexing Static and DynamicPages Static Pages which are HTML, XLS, WORD, PDF documents on web which can be easily crawled and indexed by search engines like Google and Yahoo. Static Pages over the internet can be passed into Lucene and indexed and searched with direct URLs. Dynamic Pages which are generated due to result of parameters submitted; like search results pages, Database hidden pages cannot be indexed with direct URLs. To index Dynamic Pages we need the parameters submitted by users to generate those pages.
Extracting and Indexing DynamicPages Extracting dynamic web pages which also can be called as database hidden pages needs some kind of input to generate the URLs To get the input parameters, we used of Apache Access logs which contain user request as URL. A sample entry in Apache access log is as follows: 127.0.0.1 - - [31/Aug/2005:18:44:03 -0400] "GET /archon/servlet/search? formname=simple&fulltext=maly&group=subject&sor t=title HTTP/1.1" 200 9560
Extracting and Indexing DynamicPages Contd... It contains all the information like IP-address of the computer accessing the information, date, time information accessed, Method called, Request URL, HTTP version, and HTTP code. The Request URL is the one which has all the input parameters, in this case formname=simplefulltext=maly group=subject sort=title Results page is dynamic and dependent upon the parameters passed. A full URL like http://archon.cs.odu.edu:8066/archon/servlet/searc Can be generated from Request URL by appending Website address.
Indexing Dynamic Pages… Apache Logs Parse and generate URL Results page Could be any file type Analyzer Index
Implementation The above flow chart describes the way Apache logs are parsed and URLs are generated It shows how the Results pages are fetched and extracted from the URLs The Results page is sent for analysis then Lucene generates the index which will be used for future searches.
Results: Hardware Environment Dedicated machine for indexing: No, but nominal usage at time of indexing. CPU: Intel x86 P4 2.8Ghz RAM: 512 DDR Drive configuration: IDE 7200rpm Software environment Lucene Version: 1.4 Java Version: 1..2 OS Version: Windows 2000 Apache Web server version 1.3 to 2.0 Location of index: local
Create IndexIndexByLog.java file reads the access logs on local computer, generatesthe URLs, fetches and extracts the results page from the URLs andindexes them and stores in LuceneIndex folder.
Conclusion It is very easy to implement efficient and powerful search engines using Lucene Lucene can be used to index dynamic pages and database hidden pages Web Server Access logs can be used to generate URLs and Java, Lucene API can be used to fetch and index database hidden pages. There are some security risks involved as we can reveal what users are doing what searches and other sensitive information .