The impact of web on ir
- 1. Ms. T.Primya Assistant Professor Department of Computer Science and Engineering Dr. N. G. P. Institute of Technology Coimbatore
- 2. WWW The world wide web is developed by Tim Berners- Lee in 1990 at CERN to organize research documents available on the internet. The World Wide Web ("WWW" or simply the "Web") is a global information medium which users can read and write via computers connected to the Internet. The term is often mistakenly used as a synonym for the Internet itself, but the Web is a service that operates over the Internet, just as e-mail also does.
- 3. Internet The internet is a series of huge computer networks that allows many computers to connect and communicate with each other globally. Upon the internet reside a series of languages which allow information to travel between computers. These are known as protocols. For instance, some common protocols for transferring emails are IMAP, POP3 and SMTP. Just as email is a layer on the internet, the World Wide Web is another layer which uses different protocols.
- 4. The World Wide Web uses three protocols: HTML (Hypertext markup language) - The language that we write our web pages in. HTTP (Hypertext Transfer Protocol ) - Although other protocols can be used such as FTP, this is the most common protocol. It was developed specifically for the World Wide Web and favored for its simplicity and speed. This protocol requests the 'HTML' document from the server and serves it to the browser. URLS (Uniform resource locator) - The last part of the puzzle required to allow the web to work is a URL. This is the address which indicates where any given document lives on the web. It can be defined as <protocol>://<node>/<location>
- 5. IR on Web Information Retrieval on the Web has always been different and difficult task as compared with a classical information retrieval system (Library System). Hypertext: Documents present on the web are different from general text-only documents because of the presence of hyperlinks. It is estimated that there are roughly 10 hyperlinks present per document
- 6. Heterogeneity of document: The contents present on a web page are heterogeneous in nature i.e., in addition to text they might contain other multimedia contents like audio, video and images. Duplication: On the Web, over 20% of the documents present are either near or exact duplicates of other documents and this estimation has not included the semantic duplicates yet.
- 7. Number of documents: The size of Web has grown exponentially over the past few years. The collection of documents is over trillions and this collection is much larger than any collection of documents processed by an information retrieval system. According to estimation, Web currently grows by 10% per month. Lack of stability: Web pages lack stability in the sense that the contents of Web pages are modified frequently. Moreover any person using internet can create a Web pages even if it contains authentic information or not.
- 8. The users on the Web behave differently than the users of the classical information retrieval systems. The users of the latter are mostly trained librarians whereas the range of Web users varies from a layman to a technically sound person. Typical user behavior shows: Poor queries: Most of the queries submitted by users are usually short and lack useful keywords that may help in the retrieval of relevant information. Reaction to results: Usually users don’t evaluate all the result screens, they restrict to only results displayed in the first result screen. Heterogeneity of users: There is a wide variance in education and Web experience between Web users.
- 9. IR systems includes two terms Objective Non-Objective Objective terms: It is extrinsic to semantic content. Ex: author name, document URL, date of publication. Non-Objective Terms: It is intended to reflect the information in the document and there is no agreement about the choice or degree of applicability of the terms, known as content terms.
- 10. IR Queries as follows: Keyword queries Boolean queries(AND,OR,NOT) Phrase queries Proximity queries Full document queries Natural Language Questions
- 11. WWW expanding faster than any current search engine can possibly index. Many web pages are updated frequently or are dynamically generated which forces search engines to repeatedly revisit them. Many dynamically allocated generated sites are not indexable by search engines, known as Invisible web. The ordering of results is not always solely by relevance, but sometimes influenced by monetary contributions. It is difficult with business model.
- 12. Some sites use tricks to manipulate the search engine to improve their ranking for certain keywords, known as search engine spamming User Info.needs Queries Stored Info InformationSearch/Select Translating Info needs to Queries Matching Queries to stored Information Query Result evaluation: Does the info found match user’s info needs?
- 13. Web Problems divided into 2 classes Problem with data itself Problems regarding the user
- 14. Distributed data-Documents Spread over millions of different web servers Volatile data-Many documents change or disappear rapidly Eg: Dead Links Large volume-Trillions of Separate documents Unstructured and redundant data-HTML errors, Duplicate documents Quality of data-False Information, Poor quality writing Heterogeneous data-Multiple media types(Eg: images, video)
- 15. How to specify the query? How to interpret the answer provided by the system? To get the proper result, submit a good query to the search system and obtain a manageable and relevant answer.