Online access information sources and services

Online access information sources and services
Introduction

Online information sources: summary
The following gives a general overview of online accessible information sources. This overview is not limited to or focusing on a particular concrete subject domain/area.

Online information sources: prerequisites
Before using online accessible information sources, you should ideally have some knowledge and skills related to computer hardware computer software the Internet the WWW the concept of ‘information’ information retrieval in general the information market

Discovering online access information sources
Equipment and tools required: A microcomputer Data communication facilities Tools to locate information sources Some knowledge and skills ...

Growing importance of computer network information resources
Networked information resources are growing at a high rate, not only in volume but also in importance. There are many sources there which are vital to research and many others which are useful generally. To keep abreast of their field, most academics and researchers will find an increasing need to use the network for fast and efficient communication and for access to information. If they don’t, they are likely to be left behind, because most of their colleagues in institutions around the world will be doing just that.

Online access to information: avoid network traffic jams
To access from Europe online information sources in the US, work when lines are not saturated. (better in the morning than in the afternoon)

Internet based information sources: problems / difficulties (Part 1)
Redundancy and overlap: On the one hand, there is too much information on some topics; in other words, the redundancy and overlap are high in many cases. Too few information sources: On the other hand, there are too few information sources on some topics.

No order is imposed on most sources. Quality checks / quality controls are not performed. Related to this: it is not required to register new information offered. Is the information that you find real, honest, authentic?

Change is the only constant: Information sources are constantly changing, growing, but sometimes disappearing.

Scattering: There is no single simple but powerful system to find relevant information through the Internet. In other words: integration / aggregation is still far from perfect.

Slow: The Internet is in many places and for many applications not yet fast enough.

In conclusion: Surfing, using the Internet, the WWW, can be a time sink instead of a productive activity.

Internet based information sources: how many? how much information?
More than million unique URLs in the total Internet More than 10 terabyte (= gigabyte) of text data

Increasing number of online public access databases
Source: Gale Directory of Databases, 1997.

Types of online access information systems

Types of online access information systems
We can categorize the various online accessible information systems in various ways: primary or secondary based on information contents that is offered online access method required (= communication protocol) freely accessible versus accessible for a fee computer file format (Of course these categorizations are normally not independent but related.)

Primary versus secondary computer sources / systems / services
Primary sources /systems /services directly useful Secondary sources /systems /services helping to access / use the primary services “travel agencies”, “navigation services”, ...

!? Question !? Task !? Problem !? Do you know examples of primary and of secondary online information systems?

Types of online access information systems by contents
Documents (with or without hyperlinks) Catalogues of editors and bookshops Online public access library catalogues (OPACs) Community/Campus-Wide Information Systems (CWIS) Online access databases about journal articles Electronic newsletters and journals Computer file archives (documents, programs) Interest groups (for instance Usenet Newsgroups) ...

Types of online access information systems by access method
Remote login information systems and bulletin board systems (BBS) (telnet in the Internet) Anonymous ftp servers, in the Internet Usenet News servers (nntp in the Internet) Gopher servers, in the Internet Wide Area Information Servers (WAIS), in the Internet World Wide Web servers = http servers (WWW), in the Internet ...

Types of online access information systems: “free” versus “fee”
A lot of the information on the Internet is available free of charge, but another part is only accessible when a fee is paid to the producer and / or the distributor. Some organisations pay these fees for some sources and then organise access, so that the members of the organisation can retrieve and exploit the information as if it is free of charge.

Public access information sources free of charge Fee-based online information services (NOT free of charge)

Types of online access information systems: “free” for members only
Public access information sources free of charge Fee-based online information services (NOT free of charge) Fee-based online information services, made accessible “free of charge” by an institute to its members

Types of online access information sources by file format
For instance: TXT (ASCII) DOC HTM, HTML, SHTML,… PDF PCX TIF, TIFF GIF JPG PNG AVI MPG ASF …

WWW sites classified by contents
Commercial: about 80% Other 20%: Science and education Personal others in 1999 (according to Lawrence and Lee Giles, Nature, 1999, Vol. 400, pp )

Commercial information provided through the Internet
Most of the information that is freely available on the WWW is provided by commercially oriented organisations. Thus that information is not objective or scientific in most cases, but subjective or perhaps even misleading, and certainly attracting more attention than more scientific information. (Of course many information sources are also provided by commercial organisations that belong to the so-called information industry, but these are bound to supply more objective information of high quality, as this is their way to survive commercially.)

WWW sites classified by language
English: about 87% Other languages: 13% in 1999

Internet-based encyclopedias

Encyclopedias accessible through Internet and WWW
Dictionaries and encyclopedias are the first choice among many types of information sources, when we do not need detailed information on a common topic when we want to prepare a more detailed search on an unfamiliar topic, by searching for the right spelling, synonyms, context,… Some dictionaries and encyclopedias are available through the WWW free of charge.

Encyclopedias accessible through Internet and WWW: examples
Encarta Concise Free Encyclopedia Encyclopædia Britannica only a small part is available free of charge + links to selected WWW sites Encyclopædia Britannica Concise

Encyclopedias accessible through Internet and WWW: examples
The Canadian Encyclopedia (in English and in French):

Encyclopedias accessible through Internet and WWW: overviews
Example Encyclopedias accessible through Internet and WWW: overviews A list / overview of encyclopedia on the Internet: Other lists of encyclopedia on Internet can be found as a part of more general directories of Internet-based information sources.

Internet search functions built in browser software

The Internet search functions built into browsers
Some Internet search functions are built into common leading browsers like Microsoft Internet Explorer Netscape When connected to the Internet, you can use The functions behind the “Search button” Searching through the “Address” form

The Internet search button of browsers: introduction
Common graphical browsers provide a search function and a search button. Examples: Netscape, Microsoft Internet Explorer

The Internet search button of browsers: comments (Part 1)
Such a search function offers in fact no searching, but (only) a link to a WWW site, often in the USA, which offers links or gateways to search tools on other servers. It is faster in many cases to contact search tools directly.

The Internet search button of browsers: comments (Part 2)
The gateways may offer only a limited view on the properties of the real search tool used. Such a search function can confuse users who may think that the searching capability is built more or less into the browser software, while searching relies on external servers.

Searching with browsers using the address form: introduction
A search for particular Internet documents can be performed by typing in keywords in the address form, when you are connected to the Internet, for instance with Microsoft Internet Explorer Netscape This is based on transmitting the keywords to some Internet index through the Internet.

!? Question !? Task !? Problem !? Get some experience in using the address form of your web browser program to search for documents on a particular subject that are available on the WWW.

Searching with browsers using the address form: comments
+ An advantage is the ease of use. - A disadvantage is that it less clear what really happens, than when you access a well chosen and well known Internet directory or Internet index directly.

Internet directories and indexes

Internet: meta-information about Internet information sources
in printed manuals and guides: - it is not always possible to get a copy fast - it costs money to get a copy - they are soon out of date offered on the WWW!: + directly available when we want to use the Internet + many systems are accessible free of charge + most systems are regularly updated (“intelligent agent” software on client PC)

Internet: subject-oriented meta-information offered via WWW
Information about information sources: in the form of subject guides = texts with references subject hypertext directories = subject guides key word indexes, generated automatically, for searching collections of links or forms to the above (multi-threaded search systems)

Internet global subject directories: introduction
They are virtual libraries with open shelves, for browsing. They are manually generated, man-made by many people. They can be browsed following a tree structure or a more complicated variation. The most famous of these systems belong to the most popular and most visited sites on the WWW: e.g. Yahoo!

Internet global subject directories: structure
The structure corresponds to a classification that is in most cases specific for the particular overview. In other words: the well-known and classical universal classification systems are not used in most Internet directories.

Internet global subject directories: limitations
They cover only a small number of selected WWW sites, in comparison with the total number of sites that are accessible. They are suitable mainly for broad searches that can be difficult to formulate in words, but NOT for more specific searches that require combinations of several concepts.

Internet global subject directories: searching directories with a query
Many of the Internet directories include an index to search their contents with a query. However, then the assisting classification structure is not well exploited and the user should be aware of the problems and difficulties of information retrieval with natural language queries. Furthermore, the possibility to use the system in this way may be confusing, as these directories are not real full-text Internet indexes, like those provided by other search tools.

Internet global subject directories: Yahoo!
Example Internet global subject directories: Yahoo! A hypertext global subject directory can be found at and at many other sites, including Entries are NOT rated. Accessible free of charge.

Example Internet global subject directories: searching with a query in Yahoo! (1) The directory of Yahoo! can not only be browsed, but can also be searched with a query. However, in this way the hierarchical structure is not well exploited. For the formulation of a search query, Yahoo! can provide automatic assistance related to spelling and word variations. For instance: After searching for “Capetown”, Yahoo! Answers: Other Spellings: Try searching for cape town instead.

Example Internet global subject directories: searching with a query in Yahoo! (2) When such a query does not provide results, then Yahoo! uses a much larger external Internet index (not produced by Yahoo!) to execute a query based on textual search statements. The chosen Internet index has varied over time. This mechanism is not made very clear and may confuse the user.

Internet global subject directories: Britannica
Example Internet global subject directories: Britannica A hypertext global subject directory can be found at Entries are rated. Accessible free of charge. Combined and integrated with a great encyclopedia.

Internet global subject directories: BUBL link
Example Internet global subject directories: BUBL link A hypertext global subject directory to more than WWW sites for the higher education community can be found at Accessible free of charge.

Internet global subject directories: BUBL for marine biology
Example Internet global subject directories: BUBL for marine biology

Internet global subject directories: Google directory
Example Internet global subject directories: Google directory A hypertext global subject directory can be found at Accessible free of charge. Very similar to the Open Directory Project.

Internet global subject directories: Librarians' Index to the Internet
Example Internet global subject directories: Librarians' Index to the Internet A hypertext global subject directory can be found at Accessible free of charge.

Internet global subject directories: LookSmart
Example Internet global subject directories: LookSmart A hypertext global subject directory can be found at Links are offered to LookSmart by the Internet index AltaVista. A search in the LookSmart index is also executed with the Internet index AltaVista. Accessible free of charge.

Internet global subject directories: Magellan
Example Internet global subject directories: Magellan A hypertext global subject directory can be found at Accessible free of charge.

Internet global subject directories: Open Directory Project
Example Internet global subject directories: Open Directory Project A hypertext global subject directory can be found at Accessible free of charge.

Internet global subject directories: Point (Communications)
Example Internet global subject directories: Point (Communications) A hypertext global subject directory can be found at Accessible free of charge.

Internet global subject directories: Resource Discovery Network
Example Internet global subject directories: Resource Discovery Network A collection of hypertext subject directories that focus on academic information sources can be found at Together these lead to more than selected WWW sites. Accessible free of charge.

Internet global subject directories: lists of directories
Many Internet global subject directories exist, but the ideal one is not available. Overviews / lists of Internet subject directories exist also. Examples (accessible free of charge):

Internet global subject directories: using more than one at the same time
A system allows you to use several European Internet subject directories at the same time. This is available free of charge through

!? Question !? Task !? Problem !? Try to find Internet sources which are relevant for you, by using an Internet-based global subject directory.

Internet global subject directories: evaluation criteria (Part 1)
Is usage free of charge? Wide coverage? Up to date? Frequent updates? Only few dead / broken links? Good coverage of the sources in that part of the world in which you are interested? Does the manager of the directory refuse to give priority to sites that want to pay to get a prominent place in the directory?

Easy user interface? Short response times? Are mirror sites available closer to you for faster response? Good presentation, description of each site? Is a rating, appreciation, review offered for each listed site? Is translation of documents offered free of charge?

Good documentation and online help? Good help desk available? High stability and reliability?

Are other services offered from the same site or with the same interface? Is the subject directory integrated with other services? Additional services can be an Internet index or a WWW index or a gateway to such an index for searching with a query travel guides, flight and hotel reservations, maps,... WWW-based and address directories auctions through WWW

Internet subject directories: non-global, more specific systems
a directory limited to sources in/of a country or region a directory restricted to a specific subject domain (“portal”) the complete WWW a global subject directory can lead to

Examples Internet subject directories focusing on a specific subject domain (Part 1) Computer science & engineering: Social sciences: Marine science and oceanography:

Examples Internet subject directories focusing on a specific subject domain (Part 2) Medicine and healthcare: general: Medicine and healthcare: General pediatrics:

Examples Internet subject directories focusing on a specific subject domain (Part 3) Engineering: Civil engineering: Fishing: Art, architecture and the media: or

Internet indexes: automated search tools
Several systems allow to search for and to locate many items (addressable resources) in the Internet in a more systematic, direct way than by only browsing/navigating. These systems do NOT search the contents of computers through the real Internet in real time and completely when a user makes a query. Searching in that way would be much too slow due to limitations in the technology.

Internet indexes: scheme of the mechanism
User searching for Internet based information Internet client hardware and software user interface to a search engine Internet information source Internet index search engine Internet crawler and indexing system database of Internet files, including an index

Internet indexes: description of the mechanism
Each of these search systems is based on: a database of links to pages / URLs that can be retrieved by searching with queries through a big index that is built machine-made on the basis of the contents, the texts, of these pages (to build this database and to keep it up to date, pages are continuously collected from the Internet by a “robot” computer software system) a search system with a user interface in a WWW form, to allow the user to search through that database

Internet indexes: AltaVista
Example Internet indexes: AltaVista The primary search interface can be found in the US: (These addresses all lead to the same information.) Mirror site in UK:

Internet indexes: AltaVista: features
Example Internet indexes: AltaVista: features Allows full text searching of the WWW Allows advanced Boolean searching (in “Advanced” mode) Offers relevance ranking of search results Offers a link to an Internet subject directory (Looksmart) Offers links to systems to find images, sounds,… (multimedia) in the Internet

Internet indexes: AltaVista simple versus advanced
Example Internet indexes: AltaVista simple versus advanced “Simple” is suited for instance for searches with only 1 concept expressed as a series of synonyms, narrower terms,... such as a search for a person, a company, an institute,... when ranking is important “Advanced” is suited for instance for searches with more than 1 concept so that an AND combination is useful, besides an OR combination when ranking is not important

Internet indexes: Fast = All the Web
Example Internet indexes: Fast = All the Web The search interface can be found at: You can search the WWW and ftp servers. The database is one of the biggest.

Internet indexes: Google (Part 1)
Example Internet indexes: Google (Part 1) You can search for WWW pages at Does NOT offer/allow full Boolean searches manual or automatic stemming/truncation

Internet indexes: Google (Part 2)
Example Internet indexes: Google (Part 2) For retrieval an algorithm is used that takes into account the links between WWW pages. A retrieved page is ranked higher when many sites/pages point to it “important” sites/pages point to it Searches include full text searching of files on the WWW; not only html pages, but also files in the formats Adobe PDF, Microsoft Word, Microsoft Excel, Microsoft PowerPoint, Rich Text Format,…

Internet indexes: Google additional features
Example Internet indexes: Google additional features Besides a system to search for WWW pages, Google offers also a subject directory searching for images on the WWW searching an archive of Usenet messages + posting to Usenet groups Thus Google has become a great integrator / aggregator.

Make a search with Google.
!? Question !? Task !? Problem !? Make a search with Google.

Internet indexes: Hotbot
Example Internet indexes: Hotbot The search interface can be found at You can search the WWW Based on an Internet index created by Inktomi. Allows advanced, Boolean searching.

Internet indexes: Lycos
Example Internet indexes: Lycos The search interface can be found at Has been based on various databases of WWW pages over time. In : based on the Fast database of WWW pages, that forms also the basis for the search system Alltheweb.

Internet indexes: MSN Web Search
Example Internet indexes: MSN Web Search The search interface can be found with the search functions build into Microsoft Internet Explorer and at Offered free of charge by Microsoft. You can search for Web content. Since 1998. Is based on an Internet index created by another company.

Internet indexes: coverage / size of each index
The indexes grow and their “size ranking” is variable. Biggest systems in 2002: Google ! AltaVista (Fast =) All the Web (serving also Lycos) Systems based on the INKTOMI database of WWW pages, such as Hotbot, MSN Web search,…

!? Question !? Task !? Problem !? Try to find Internet sources which are relevant for you, by using an Internet index.

!? Question !? Task !? Problem !? Develop a suitable search query and apply this with an Internet search engine to find “general reviews about monitoring seawater pollution” Some advice: use synonyms, narrower terms, truncation, and Boolean combinations.

Internet indexes: delay in indexing new pages
The great, well known, international Internet indexes have a delay of more than 1 month in indexing new pages. (according to Lawrence and Lee Giles, Nature, 1999, Vol. 400, pp ) So they are not suitable to search for rapidly changing recent information (such as “news”) (unless they index a small selection of important news sites more frequently.)

Internet indexes: non-global, regional systems
the complete WWW a global Internet index an index limited to sources in/of a country or region

an Internet subject directory or an Internet index?
!? Question !? Task !? Problem !? Which Internet search system is closest to a classical library catalogue: an Internet subject directory or an Internet index? A directory because it does not allow the user to search the full texts of documents and the documents have been described manually by human beings (like a classical library catalogue), whereas Internet indexes work almost without human intervention and they offer a full text index.

!? Question !? Task !? Problem !? Which differences do you see between a classical library catalogue and an Internet index?

Internet indexes: comparison with library catalogues
Most Internet indexes have a larger database than most catalogues. Internet index databases do not correspond as well to the Internet as a normal, good catalogue corresponds to the collection, because the documents on the Internet change more often and their number is growing fast. Most Internet indexes contain all the words of the documents that they index, whereas catalogues only contain short descriptions of the documents.

Internet indexes: variations among various systems
Besides their common aims and characteristics, we can nevertheless see differences, variations among the searchable Internet index systems. To illustrate these variations and to assist Internet users to make a decision on which search system to use, the following list of some features and evaluation criteria can be useful.

Internet indexes: evaluation criteria (Part 1)
Is usage free of charge? How complete is the coverage? Is the coverage good (or poor) for a particular geographic region? Is the coverage good (or poor) for a particular type of documents? Is the searchable database up to date? Is the database updated frequently? Do the search results contain only few dead (broken) links?

Is spamming filtered out, to give other pages a better chance of turning up in the result set? Can the system cluster presumed duplicate documents in the results? Or does the system simply eliminate presumed duplicate documents from its database? Does the database system work with a full text indexing of each ASCII and HTML document that has a place in the database, so that full text searching is possible?

Are the contents of meta-fields also indexed to make them searchable? Does the system index also the text in files on the web that consist of non-ASCII codes to make these also searchable and retrievable? For instance files in the format of the various versions of Microsoft Word Microsoft PowerPoint Adobe Acrobat (Portable Document Format)

Field indexing, so that searching for the contents of a particular field is possible? for instance: the HTML title, HTML keywords, URL, date, link, Java applet, text, image file, sound file, video file,...

Does the system offer powerful search options like truncation? word stemming? Boolean search combinations? proximity searching? automatic translation of your search terms in several other languages? spelling check of your search terms?

Can the results be limited to a certain time period? For instance based on the date of the file as noted by the server computer, or of the most recent indexing of the file Is the user interface easy to understand and efficient to use? Is a user interface offered in your own language? Does the system rank the items in the result set according to their presumed relevance?

Possibility to combine Boolean retrieval with relevance ranking of results? Can the results be ordered according to date of the file as noted by the server computer, or of the most recent indexing of the file Can the results be ordered according to size? Can all the results (documents) from the same site be grouped together?

Can the system rank the results (documents) on the basis of the number of WWW hyperlinks to that document? The system does not place/rank some results (documents) higher in the results list, on the basis of payments by the producer of those documents to the search system company.

Short response times? Are mirror sites available closer to you for faster response? Does the system offer a good presentation format of each result (document/page/item)? For instance: are search terms indicated / highlighted in the results? Good and detailed summary of each result available? Offers an analysis of words occurring in the results, which can help you to refine a search?

Is translation of documents offered free of charge? High stability and reliability? No large variations/fluctuations in the results from identical searches at different times. Good documentation and online help? Good help desk available? Can the search system provide updated results through electronic mail, as a current awareness tool?

Other services available besides the normal WWW index: index to news resources, that is more frequently updated? anonymous ftp file index? gopher index? searchable Usenet newsgroups archive? Internet subject directory? White pages = people finder = addresses = ... WWW-based and address directories auctions through WWW

Is the search/query also submitted to another database to obtain more results? for instance: to a book database to obtain book descriptions besides WWW documents

!? Question !? Task !? Problem !? Why do different Internet search engines (in most cases) give different results for an identical search?

Internet indexes for citation searching: introduction
Some Internet indexes / search engines allow you to search for documents / pages / URLs that link to a particular page, to some URL that you already know (such as one of the web pages that you have developed or that you have made available yourself). Linking to a URL is similar to citing an information source. Such search systems can be used to analyse web citations. Web citations are sometimes named “sitations”.

Internet indexes for citation searching: query syntax
For details about the required query syntax, query formulation, see the online manual or help pages of the search system that you want to use.

Internet indexes for citation searching: link versus linkdomain
Do not confuse links to a particular web page, using for instance a query like “link:this_page.html” with links to a whole web domain, using for instance a query like “linkdomain: this_site”

Internet indexes for citation searching: examples of systems
AltaVista ! but note that “Simple search” and “Advanced search” may give different results Hotbot Google (Northernlight !) by using a query like “link:this_page NOT url:this_site”

Internet indexes for citation searching: applications
Citation searching on the WWW or on an intranet can be used to get an idea of the importance, the fame, the impact of a particular web document, as measured by the number of links/citations to that page to find out who has considered a particular page as interesting enough to make a link to to find comments/criticisms on a particular web document

Use a citation search engine.
!? Question !? Task !? Problem !? Use a citation search engine.

Internet indexes for citation searching: evaluation criteria (1)
Is usage free of charge? Is left truncation possible of the URL for which you want to find citations, so that citations to this and to underlying documents can be found in one action? Is right truncation possible of the URL for which you want to find citations, so that citations to this and to related documents on multiple sites can be found in one action?

Can self-citations and/or other documents be excluded from the search results in the query used to find citations? How complete is the coverage of the citation search system? Is the coverage of the search system good or poor for a particular geographic region? Is the coverage of the search system good or poor for a particular type of documents?

Up to date? Frequent updates? Only few dead / broken links? Is some form of relevance ranking of results offered? Which criteria are used for the ranking? Can the results be ordered according to date of the file as noted by the server computer, or of the most recent indexing of the file Can all the results (citing documents) from the same site be grouped together?

Is a good and detailed summary of each result made available? High stability and reliability? No large variations/fluctuations in the results from identical searches at different times. Good documentation and online help? Good help desk available? Can the search system provide updated results through electronic mail, as a current awareness tool?

!? Question !? Task !? Problem !? Compare Internet directories with Internet indexes (collection of data, coverage, ease of use,...)

Multi-threaded Internet search systems: scheme 1
Client computer + WWW client program Internet WWW WWW server computer User WWW server computers with Internet search systems In Out

Multi-threaded Internet search systems: scheme 2
Internet WWW User WWW server computers with Internet search systems Client computer + Multi-threaded Internet search client program In Out

Multi-threaded Internet search systems: scheme 1+2
Client computer + WWW client program Internet WWW WWW server computer User WWW server computers with Internet search systems Client computer + Multi-threaded Internet search client program In Out

Multi-threaded Internet search systems: vocabulary
“multiple search systems” “multi-search systems” “meta-search systems” “intelligent Internet search agents” “Internet meta-search tools” ...

Multi-threaded Internet search systems: relations
User an Internet meta-search system Internet search system 1 Internet search system 2 Internet search system database 1 Internet search system database 2 WWW pages

Multi-threaded Internet search systems: server-based or client-based
Online accessible on a server in the Internet. On the client, “meta-search software”.

Multi-threaded Internet search systems: server-based
Examples Multi-threaded Internet search systems: server-based = a collection is available from

Multi-threaded Internet search systems: client-based
Examples Multi-threaded Internet search systems: client-based Example: Copernic

Multi-threaded Internet search systems: advantages
+ Saves time when otherwise more than only 1 Internet index would have to be used one after the other; for instance when searching for specific information that is hard to find in any single Internet index. + Some meta-search systems provide a useful integration of the results they get from the various primary search systems, with a removal of repeated results. + Some client-based meta-search systems show links among retrieved pages. J

Multi-threaded Internet search systems: disadvantages (Part 1)
- It is not always clear through which Internet indexes the meta-search system will search. - Not all meta-search systems can search all the major primary search systems. - The systems are often slower than a direct, primary search system.

Multi-threaded Internet search systems: disadvantages (Part 2)
- Only a limited number of the results that can be obtained from the various Internet indexes are shown. - Some specific or advanced features of the individual search systems cannot be used through all the meta-search system, such as: Boolean searching, proximity searching, field searching, categorization of search results,...

Coverage of Internet directories and Internet indexes
Internet information sources A global Internet directory A global Internet index

Global Internet search tools: a comparison
Global Internet directories Only a limited selection of Internet sources Browsing information sources is easy Good for broad searches Global Internet indexes About 1/3 of the Internet is covered by an index Searching requires some skills and knowledge Good for specific, narrow searches Multi-threaded search systems These get information from directories and indexes Searching requires some skills and knowledge Good when even 1 index does not yield information

!? Question !? Task !? Problem !? Which information on the Internet is not covered by many searchable Internet indexes?

Internet indexes cover only a part of the Internet: introduction
The “visible” part of Internet The “hidden, invisible” part of Internet and the WWW, (that is not searchable using a global index like, AltaVista, Google...)

Internet indexes cover only a part of the Internet: scheme
Databases and file archives accessible through the Internet telnet ftp ... Internet WWW CGI, ASP,... Static indexable texts in the WWW ( = on HTTP server computers) covered partly by Internet indexes Information accessible only when passwords are used Rapidly changing information, such as news PDF files Word files

Give an example of a database that is accessible through the WWW.
!? Question !? Task !? Problem !? Give an example of a database that is accessible through the WWW.

Internet indexes cover only a part of the Internet: conclusion for users
When you want to retrieve information about a particular subject from the Internet, use not only WWW indexes, but use also other sources accessible through the Internet anonymous ftp file archives, based interest groups; Usenet newsgroups, databases (book and journal bibliographies, library catalogues, archives of group messages, directories, atlases,…) rapidly changing information, such as news information accessible only when passwords are used

Gateways to Internet databases accessible free of charge
Most Internet search engines search classical, static WWW pages and not databases accessible through the WWW. However, some systems offer a gateway to search databases on the Internet. Examples: (See also other more general directories/overviews/lists of Internet information sources.)

Finding multimedia files on the Internet
Several public access search systems are available free of charge to search the Internet for multimedia files: images / pictures (either artwork, either photos, or both) sound / audio files (music, speeches,...) video

Finding images on the Internet: introduction
Several public access search systems are available free of charge to search for images / pictures (either artwork, either photos, or both) on the Internet. When searching for images, the search results from such a system offer not only links to the image files on the Internet, but also directly small versions of the images (so-called “thumbnails”).

Finding images on the Internet: examples of search engines
!!! ! !!!! or through !! (also audio and video, choose not the normal text search, but IMAGES in the user interface.) !

Finding images on the Internet: screen shot of a Google image search
Examples Finding images on the Internet: screen shot of a Google image search

!? Question !? Task !? Problem !? Use a specialised search engine to find images about a particular subject on the Internet.

But is there a simpler way to track changes?
!? Question !? Task !? Problem !? When you want to know if the contents of a particular WWW page has changed, then you can of course check/read/visit that page regularly. But is there a simpler way to track changes?

Current awareness services focusing on WWW pages: introduction
Tracking changes in one or more public access pages on the WWW or finding new pages, is possible by using one of the available, suitable, programs loaded on your client workstation through “alert” services based on a server on the WWW that track updates for the user/subscriber and send alerts by to the user/subscriber Few systems are free of charge.

Current awareness services focusing on WWW pages: Tracerlock
Example Current awareness services focusing on WWW pages: Tracerlock can use one of several external Internet indexes with a simple search query given by you, to discover relevant changed or new WWW pages for you in the future

!? Question !? Task !? Problem !? Track the changes of a WWW page, by using a service free of charge on the WWW.

Public access book databases

Public access book databases: introduction
Even in this age of Internet-based information sources, a lot of information is still distributed in the form of printed books. The contents of most books is (still) not available on the Internet. Most Internet search tools do NOT allow you to find out about the existence of books that may be interesting for you. So, specific search tools to find books can be useful.

Public access book databases: an overview
(Databases by publishers.) Databases by book distributors / bookshops! Online public access library catalogues (Databases of computer-based versions of books.)

Public access book databases provided by bookshops
To find currently available books, the bibliographic databases assembled by big bookshops are interesting. Several offer a good coverage and are accessible free of charge.

Book databases accessible free of charge: examples (Part 1)
Amazon.com (US): note: amazon, NOT amazone Barnes and Noble (US): Blackwell’s on the Internet (International, academic books):

Book databases accessible free of charge: examples (Part 2)
VLB for books in German For books in French Boeknet - De Nederlandse Internet Boekhandel (Dutch)

Free public access bibliographic book database + price comparisons
Even comparisons of the catalogues of shops of books (as well as of music, movies and many other goods) are available free of charge. See for instance

Example of an international public access dissertation database
Examples Example of an international public access dissertation database The dissertation database of UMI is available from: A part is available free of charge.

Collection of links to public access book databases
Examples Collection of links to public access book databases See for instance Internet directories like Yahoo! that lead to information about books.

!? Question !? Task !? Problem !? Search for titles of books which are relevant for you, using an online database provided by a book publisher or bookshop.

Current awareness service for books
Some systems can alert the user that a new book has been published when this fits the interest profile of the user. Such an interest profile can be stored on the server of the system in the form of keywords, or subject categories / subject fields Example:

Public access book databases: evaluation criteria (Part 1)
Is usage free of charge? Wide coverage? Also for books in your preferred language? Specialized coverage for particular subjects? Up to date? Frequent updates? Abstracts, summaries, descriptions, tables of contents included? Full text indexing of each item in the database, so that full text searching is possible?

Field indexing, so that searching for the contents of a particular field is possible? for instance the title the date of publication the author the publisher the language

Does the database producer improve retrieval by adding subject terms, or by classifying the books in categories Powerful search options: truncation? stemming? Boolean search combinations? proximity searching,…? spelling check of your search terms? translation of your search terms in several other languages?

Easy user interface? Is a user interface offered in your own language? Relevance ranking of results? Possibility to combine Boolean retrieval with relevance ranking of results? Can results be limited to a certain time period? Can the results be ordered according to date, size, origin,...?

Good presentation of each result? Does the system offer a current awareness service, sending information on new titles that may be of interest to you? Short response times?

Are other services offered from the same site or with the same interface? Is the system integrated with other services? Additional services can be searchable databases of videos, of music CD’s, CD-ROMs, DVDs, all for sale also a subject directory for browsing, besides the database with index for searching WWW-based and address directories auctions through WWW

Library Online Public Access Catalogues = OPACs

Online Public Access Catalogues of libraries
Mainly to find older books, the catalogues of libraries can be useful. Most are accessible online and free of charge.

Online Public Access Catalogues = OPACs: definition
a term used to describe any type of computerized library catalog offered to the public by online login

!? Question !? Task !? Problem !? Which protocols are used by managers of catalogue systems to provide access to OPACs through the Internet?

Online Public Access Catalogues: Internet protocols used for access
telnet (WAIS) Z39.50 WWW / http / html WWW / http / html + Z39.50 !

Online Public Access Catalogues: directories
The most up-to-date directories and pointers to online access library catalogues are offered online by many WWW servers.

Online access library catalogues: The British Library
Example Online access library catalogues: The British Library Accessible online via WWW: Since 2000: Access free of charge

Online access library catalogues: The British Library: screenshot
Example Online access library catalogues: The British Library: screenshot

!? Question !? Task !? Problem !? Search for titles of books which are relevant for you, in the British Library.

Online access library catalogues: The Library of Congress, U.S.A.
Example Online access library catalogues: The Library of Congress, U.S.A. >15 million books + >10 million other documents In Washington DC, U.S.A. Accessible online via WWW Access free of charge

!? Question !? Task !? Problem !? Search for titles of books which are relevant for you, in the Library of Congress catalogue.

Fee-based online public access information services

A lot of the information on the Internet is available free of charge, but another part is only accessible when a fee is paid to the producer and / or the distributor. Some organisations pay these fees for some sources and then organise access, so that the members of the organisation can retrieve and exploit the information as if it is free of charge. The first commercial computer systems that make information available online were born around 1975. Most of them are now also available through the Internet.

Fee-based online access services: examples (Part 1)
Name America On Line OCLC Ovid Technologies CompuServe Cambridge Data-Star Dialog EBSCO Location of the computer(s) U.S.A. U.S.A. U.S.A. U.S.A. U.S.A., Taiwan, UK Switzerland

Fee-based online access services: examples (Part 2)
Name Elsevier ScienceDirect Factiva ISI (Web of Science, JCR,…) LexisNexis MSN (Microsoft) Prodigy Silver Platter STN Swets (e-journals) ... Location of the computer(s) U.S.A. U.S.A. U.S.A., The Netherlands,... Germany - U.S.A. - Japan The Netherlands ...

Online information services: various names for similar systems
(fee-based) online (access) information service (fee-based) online (access) computer service databank database vendor host computer aggregator ...

Online information services: access methods
Using generic, common communications software through the telephone network (telephone + modem) through X-25 data communication networks through Internet, using client-server systems: telnet WAIS or Z39.50 http (WWW)! (Examples: (Using client software dedicated to the particular service)

Online information services: total size of their databases
The big host systems and the public access WWW pages offer a comparable quantity of information: WWW offered about 8 terabytes (= gigabytes) of text data (according to Lawrence and Lee Giles, Nature, 1999, Vol. 400, pp ) Dialog offered about 9 terabytes (= gigabytes) (in 1998) 6 billion pages of text 3 million images

Database producers and database hosts / distributors
Some database producers distribute directly their own information from their own servers, and do not (only) rely on external host servers. Examples: Cambridge Scientific Abstracts Elsevier Companies / Organizations Database producers Hosts = Database vendors

Database hosts / distributors: evaluation criteria (Part 1)
Contract required? A priori payment required? Stability / history / evolution / future of host? Low costs of data communication? Many databases available? Whole records available (or only parts)? Frequent updates? Whole database available? As one file or fragmented?

Price of access? Price of information? Powerful search options: truncation, Boolean combinations, proximity searching,…? Can the indexes of more than one database be searched simultaneously? Speed of retrieval? Relevance ranking of results? Fast response? Accuracy of data communication? Clear output format?

Online indication of costs? Easy user interface? Practice free of charge? Good manuals, documentation and online help? Training courses available? Quality? Good help desk available? Gateway service offered? ...

Online use of external databanks: fixed cost factors
Personnel ! Equipment and maintenance of equipment Contract with public data communication service Contracts with hosts Manuals about external databanks Directories of databases Training of personnel Journals about online information retrieval ...

Online use of external databanks: variable cost factors
Data communication Access to host / databank (time spent online) actions performed! Royalties for acquired information Storage of output / results (Printing hard copies by the host) Printing and/or storing on disk ...

Searching indexes of more than one database simultaneously
Application/purpose: Find most appropriate database, easily, fast and cheap

Online access versus CD-ROM databases: factors to compare (Part 1)
User interface Availability of the required data on the medium? Time available for access? Hard- and software required for access Maintenance of the required hard- and software Dependence of data communication system for online access How many databases available on the same system?

Online access versus CD-ROM databases: factors to compare (Part 2)
Searching in more than one database at the same time? Is the complete database accessible in one search? Flat fee for most CD-ROMs versus pay for what you get with many online databases Update frequency of database(s) ...

Databases of online public access databases
Example Gale directory of databases ! Their coverage: online access databases (databases accessible on CD-ROM) ...

Databases of databases: Gale
Produced in U.S.A. Not free of charge Available in various formats: printed on CD-ROM online via the host systems Data-Star, Dialog, with a payment required for each use online through the Internet through various hosts, for a fixed price per year to be paid in advance

!? Question !? Task !? Problem !? Identify databases which may be relevant for you, using a directory of online databases.

!? Question !? Task !? Problem !? Example
When ASFA is available to you, develop a suitable search query and apply this to find documents about monitoring sea water pollution. Some advice: find and apply the relevant controlled terms (descriptors) from the thesaurus used by ASFA. Descriptors: Marine pollution; Pollution monitoring

!? Question !? Task !? Problem !? Example
When ASFA is available to you, develop a suitable search query and apply this to find documents that describe the state of the art in fishing by using poison in the lakes of Tanzania. Some advice: find and apply the relevant controlled terms (descriptors) from the thesaurus used by ASFA. Hint: ASFA uses a controlled term for “fishing with dynamite”: “explosive fishing”

Online access databases about journal articles

Online access databases about journal articles: overview
Thousands of fee-based online access databases offer bibliographies or full-texts of journal articles in particular subject domains. Only few large databases offer access to bibliographies of articles published in journals, free of charge.

Online access databases about journal articles: Northern Light
Example Online access databases about journal articles: Northern Light Northern Light allows searching for the full text of articles from many journals/magazines. Searching is free of charge. Available from Payment is required to receive the full text of an article.

Online access databases about journal articles: Ingenta (1)
Example Online access databases about journal articles: Ingenta (1) Ingenta Journals allows you to search a bibliographic database of millions of journal articles, including titles, authors, in many cases abstracts. Searching is free of charge.

Online access databases about journal articles: Ingenta (2)
Example Online access databases about journal articles: Ingenta (2) Payment is required to receive the full text of an article. Ingenta has acquired Uncover in 2000. Available from

Online access databases about journal articles: Article@INIST
Example Online access databases about journal articles: allows you to search in a bibliographic database, NOT full-text (Journal articles, Journal issues, Books, Reports or Conferences, doctoral dissertations) at the Institut de l'Information Scientifique et Technique, France. Searching is free of charge. Available from Payment is required to receive the full text of an article.

Online access databases about journal articles: Infotrieve
Example Online access databases about journal articles: Infotrieve Infotrieve allows you to search free of charge in a bibliographic database of the articles of more than journal titles and conference proceedings, NOT full-text. Current awareness services are also offered free of charge. Available from Payment is required to receive the full text of a document.

!? Question !? Task !? Problem !? Search for titles of journal articles which are relevant for you, in a database provided free of charge.

Online information sources about journal titles

Online information sources about journal titles: introduction
Besides directories / catalogs / overviews /databases / lists of electronic, computer-based, online accessible newsletters, newspapers, journals, and besides databases about published articles in journals (bibliographic databases), information is also available through the WWW about journal titles in general: their exact names, name changes, editors, prices, formats (printed or electronic online), full text availability online, …

Online information sources about journal titles: example
Available free of charge:

Electronic newsletters and journals

Electronic newsletters and journals: introduction
Since the end of the 1990s, electronic journals have become a new communication medium that cannot be neglected. Author / Sender Editor Reader / Receiver

Electronic newsletters and journals: variations on a theme
We can distinguish several methods of distribution and access of formatting the information (PDF, HTML,…) of pricing and licensing of restricting access (authentication and authorization of legitimate users) to integrate access to e-journals with access to other information sources

Electronic newsletters and journals: various types and the price of access
We can distinguish various types: equivalents of a version printed on paper Published almost simultaneously Print version published long time before electronic version = long delay for the electronic version purely electronic publications Price of access: from free of charge to very expensive

Electronic newsletters and journals through the WWW
The WWW has become the most important platform for access to electronic newsletters and journals.

Which pricing schemes for access to electronic journals do you know?
!? Question !? Task !? Problem !? Which pricing schemes for access to electronic journals do you know?

Electronic newsletters and journals: pricing (Part 1)
Several categories (pricing models) can be distinguished: Free access for all Access without extra costs besides the price for the print version; coupled with the printed version

Access with an extra cost on top of the price for the print version (for instance at 110%, or dependent on the number of potential users); coupled with the printed version Access not free of charge, but access to the electronic version only, at a lower price than the price of the printed version (for instance at 80%, or dependent on the number of potential users); not coupled to the printed version

Access not free of charge; a printed version does not exist One price for access to many or all of the electronic journals of an editor = “package deal” Access not free of charge and the journal is one component of a bigger full-text database Pay per view: payment for each article that is viewed Payment for a license in the framework of a consortium of organisations (possible advantages of this approach: bundling of expertise, lower prices,…)

Access not free of charge; a group of authorised users selects a fixed number of articles from a collection of many journals and can then access these articles without further limit

Electronic newsletters and journals: authentication
To control access to fee based electronic journals some method for authentication and authorization is used by publishers or distributors: On the basis of the range of IP-addresses of the computer workstations used by the organisation On the basis of a username and password couple that are constant, permanent or that are changed often by the information provider Or based on a combination of those methods

Electronic newsletters and journals: authentication problems
Up to now, the authentication methods are far from perfect: Authentication by IP-address gives problems with users on “external”, “unknown” workstations outside the simple IP-address range Authentication by passwords is complicated and passwords cannot be kept secret.

Electronic newsletters and journals: problems and challenges
There is no central database with all article titles, summaries, and full contents. There is not even a central, complete and up to date directory of journal titles. There is no standard licensing/pricing method. Not all electronic journals are accessible through 1 user interface. Many passwords must be used. Archiving (By whom? For ever?)

Electronic newsletters and journals: integration with other sources
It is not (yet) clear and straightforward how electronic journals should be integrated in a library collection in a library web site in the catalogue database in interlibrary lending (depends on licensing agreement for each individual journal)

Electronic newsletters and journals: integration and access methods
Access can be possible through A gateway offered by a subscription agent or the publisher A commercial bibliographical database A web-based static listing of journal titles A web-based OPAC (for instance in the MARC 856 field) A local searchable database for e-journals Special linking mechanisms, such as SFX / OpenURL (commercialised by Ex Libris) COM P L E XI T Y

Electronic newsletters and journals: more than one access method
How should libraries and readers/users cope with the fact that many e-journals can be accessed in more than one ways, that is by hyperlinks starting from various information systems or services, while authentication and authorization is NOT fully automated for all those systems, once that a licensing agreement has been established? What mechanisms can offer support for this situation?

!? Question !? Task !? Problem !? Find out how you can efficiently access electronic journals from your institute.

Electronic newsletters and journals: usage statistics
Statistical data related to usage: the collection, standardization and exploitation should be developed further.

!? Question !? Task !? Problem !? How to find out if the full text of a published printed article is also available online?

Directories of online access electronic archives of printed journals
Several directories / catalogs / overviews are available of electronic, computer-based, online accessible archives of printed sources (newsletters, newspapers, journals,...): Fulltext Sources Online (printed) taken over in 1998 by the publisher Information Today Net.Journal Directory (printed) ...

Directories of online access electronic journals
Several directories / catalogs / overviews / databases / lists are available of electronic, computer-based, online accessible newsletters, newspapers, journals,...: Scholarly journals distributed via the World Wide Web Newjour: Electronic journals and newsletters

Computer-based information sources: criteria to evaluate their quality

Computer-based information sources: evaluation criteria (Part 1)
Besides more general criteria applicable to all information sources, for those sources that are based on computers and networks we see the following criteria: Easy to navigate? User-friendly information system? Easy for users to orientate themselves within the resource and to find their way around it? Is the resource organised into manageable chunks of information that can be browsed easily?

Is a contents page or index offered that describes what is contained within the site? Are there good navigational links within the pages (e.g. 'back', 'forward', 'home') Are the links clearly labeled? Is the navigation process supported by images? Is there a single downloadable file for documents that exist as a series of separate pages? Is there a search facility within the resource?

Good user support? Good support that is offered to users to help them answer queries and problems that arise whilst using the resource? Good computer-based, contextual help, documentation, training materials or tutorials? contact(s) and telephone number(s) available?

Based on appropriate technologies? Are technologies and standards used that will enable users to access and utilize all aspects of the resource? Does the resource avoid that proprietary software should be used? Does the resource avoid the use of proprietary extensions to HTML, which some browsers will not be able to recognize?

Does the format allow access to the resource for all users, even for instance sight impaired and those who can only navigate by using the keyboard? Information integrity / High stability of the contents / Low volatility of the contents? Is there adequate maintenance of the information content?

System integrity? Site integrity relates to the stability of the site over time. This usually relates to the work of the site manager or web master. Realise that individual sites can be moved or withdrawn at any time by those responsible for publishing information on the Internet, and that addresses, file structures, formats and interfaces can be altered without warning. Is the site current and up to date?

Is the site proven to be or expected to be durable in nature? Is the site adequately administered and maintained?

Computer-based information sources: The Internet Detective
A tutorial in English about how to assess the quality of WWW-based information resources can be accessed online free of charge through the WWW:

!? Question !? Task !? Problem !? Use The Internet Detective to learn more about assessing the quality of WWW-based information.

Future trends

Online access information: future trends
An increasing amount of information becomes available online. A growing amount of this online information becomes available free of charge. The quality of server and client software is growing. A consequence is: An increasing number of end-users searching for information online.

Online access information: future trends regarding software
From a mix of user interface + data offered both online by the server / host, to an increasing use of client-server architecture. Less usage of client software specific for one application, but increasing number of applications of generic, popular, widely distributed WWW client software. Increasing integration of various types of information sources, servers, and client software.

Online access information: conclusion
In the case of simple information needs, the WWW and the search tools can work like “magic”. However, in the case of more complicated information needs, there is still is no “magic button” that brings you immediately to all the required information.

Online access information sources and services

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