1

Pertemuan 20 Searching Mechanisms

Matakuliah : M0284/Teknologi & Infrastruktur E-Business

Tahun : 2005

Versi : <<versi/revisi>>

2

Learning Objectives

• Describe the role of search engines in e-business

• Explain how search engines work• Describe use of search engines in intranet and

extranet environment• Identify important search engines in the market• Describe a flexible search strategy

3

Directories and Databases

• Searchable subject/ topic directory yahoo.com– A hierarchy of topics entries are submitted

to the site, verified and included in the directory. Good quality control

• Virtual Librarieshttp://sunsite.berkely.edu/internetindex

• Specialized databases both content and index– Lexis-Nexis, Medline, Dialog

4

Meta-Search Engines

•Coordinate the services of several search-engines

•Dogpile www.dogpile.com•Metacrawler www.metacrawler.com

5

Search Engine Evaluation

• Recall– Ratio of pages returned to total volume of

pages on the world wide web

• Precision – Ratio of pages returned that are relevant

• Conflicting nature of the above two criteria

6

Search Engine Evaluation

• Directories like Yahoo are high in precision, poor in recall

• General sites such as Altavista are high in recall and poor in precision

• Design challenge in search engine is to have both high precision and recall

7

Search Engine Evaluation

• Search life cycle– Initial phase exploration phase high recall

is required– Later phase exploitation phase high

precision is required

8

Popular Search Engines

• Google

• Yahoo

• Altavista

• Northern Light

• Lycos

• Excite

9

Flexible Search Strategy

• Determine specificity of search required– In exploration or exploitation phase?

• Choose a search engine that suits the specificity of search – meta-search engines for initial phase of

exploration

• Build a search query – Boolean statements

10

A Search Example

• How to develop a small business in the engineering area and obtain a prospective list of customers

– Start with a virtual library

11

A Search Example

12

A Search ExampleResponse to query “small business”

13

A Search Example

• A site on small business

14

A Search Example

• Business Week Site on Small Business