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Federated search engines: een inleiding Paul.Nieuwenhuysen @ vub.ac.be Prepared to support a presentation at the 1-day conference about “Federated search engines” organized by VVBAD, section School Libraries, in Brussels, Belgium, on May 5, 2009
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These slides should be available from the WWW site http://www.vub.ac.be/BIBLIO/nieuwenhuysen/presentations/ (note: BIBLIO and not biblio) and also from the WWW site of the organisers of the conference = VVBAD
3 1. Introduction and definition 2. Problem statement
- contents - summary - structure - overview
3. Federated search engines as a partial solution 4. Meaning and confusion 5. Advantages / benefits ☺ 6. Difficulties / limitations 7. Implementation
of this presentation
8. Putting federated searching in a wider context 9. (Some good information sources about federated searching)
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Federated searching Introduction and definition
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Introduction: scattering of sources • Users want to exploit information sources fast and effectively. • This is hindered by the fact that digital, electronic information sources that may contain relevant information are created and scattered, distributed on numerous computers all over their intranet or even over the Internet and the WWW.
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Introduction: scattering of sources • In other words: integration / aggregation is still far from perfect.
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Introduction: scattering of sources difficulties • Various sources »must be used one after the other which requires many decisions and actions and costs time »offer different user interfaces in the retrieval phase, which is confusing and time consuming »offer each found information item in various formats »display items in different ways on a computer display
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Federated searching Problem statement
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Introduction: problem statements Which methods have been developed and applied to cope with this reality?
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Federated searching Federated search engines as a partial solution
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Method 1: Merging = aggregating into a searchable database User User
User User
Search engine
Aggregated database
Database or web site or…
Database or web site or…
Database or web site or…
o
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Method 1: Merging = aggregating into a searchable database User User
User User
Search engine
Database or web site or…
Aggregated database
Database or web site or…
Database or web site or…
o
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Method 2: Federated searching through scattered databases User User
User User
Federated search engine
Search engine
Database
Search engine
Search engine
Database
Database
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Federated searching: definition An ideal federated search system 1. allows a user to formulate a query, 2. it adapts/transforms this query, so that it can be sent with a proper syntax to each search engine of a chosen set/group of disparate databases, 3. it broadcasts this query to those databases, 4. it collects results from each database, 5. (perhaps: consolidates these results into 1 result set) 6. (perhaps: detects and removes duplicate items) 7. shows the final results to the user, in a unified format 8. allows the user to sort the results by various criteria
☺
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Federated searching: approach • This type of computer systems helps to integrate access to distributed databases in one search action, as far as possible. • The catalogue of local library holdings can be one of the target databases.
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Federated searching: scheme End Enduser user
☺ ☺
End Enduser user
☺ ☺
portal portalfor for meta-searching meta-searching ==federated federatedsearching searching ==cross-database cross-databasesearching searching
information sources
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Federated searching through scattered databases: why? • Applications: »Finding flights to a particular destination offered by various airline companies »Finding the availability of rooms in various hotels »Finding information in various databases related to a particular museum »Finding information in bibliographic databases !
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Federated searching through scattered databases: why?
The Theperfect perfecttrip: trip: 1.1. AAcheap and cheap andnice niceflight flight 2.2. AAcheap cheapand andnice nicehotel hotel 3. A visit to a nice museum 3. A visit to a nice museum 4. 4. Something Somethingnice niceto toread read(free (freevia viayour yourlibrary) library)
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Example
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Federated searching: application: finding a suitable flight
Example
Federated searching: application: finding a hotel room in some city
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Example
Federated searching: searching in a museum
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Example
Federated searching: searching in a library
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Federated searching: integrating access Intranet Intranet Articles Articles
WWW WWW search searchengines engines
Journals Journals
Catalog Catalog database(s) database(s) of ofother otherlibraries libraries
Publishers Publishers Databases Databases (full-text (full-textor orbibliographic) bibliographic)
Local Locallibrary librarycatalog catalog database(s) database(s)
Meta-searching Meta-searchingsystem system
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Federated searching: produce - distribute - implement Producers Producers==developers developers==creators creators
Intermediate Intermediatesellers sellers==distributors distributors
Implementers Implementers==users users(for (forinstance instanceaalibrary library
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Federated searching: examples of commercial software Producing company
Distributing / selling company
Product name
Ex Libris
MetaLib
Infor (was GEAC)
V-Spaces
MuseGlobal
MuseSearch
MuseGlobal
CSA
Serials Solutions
360 Search
Serials Solutions
WebFeat
Groxis Vivissimo Infotrieve …
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Federated searching Meaning and confusion
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Federated searching: terminology / vocabulary / synonyms federated searching = meta-searching = metasearching = cross-database searching = multi-database searching = multi-threaded searching = one-stop searching = poly-searching = polysearching = broadcast searching = searching through a portal (but the term “portal” is used also with other meanings)
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“Federated searching” meaning and confusion Here and in many other contexts, the term “federated searching” is used as a synonym for “meta-searching”.
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“Federated searching” meaning and confusion However, some use the terms “federated searching” and “meta-searching” with DIFFERENT meanings. »“Federated searching” as searching through a database that results from merging several databases. So this is certainly NOT equal to “meta-searching”. »“Federated searching” as meta-searching that is followed by merging (federating) the items retrieved from various databases into only 1 set, ordered in one way or another. This language problem creates confusion.
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“Federated searching” meaning and confusion • Furthermore: A federated search engine as software product is NOT the same as a federated searching system implemented as a service that can be available for all on the WWW, to search »public WWW search engines »bookshop databases »library catalogs / holdings »flight databases »hotel databases
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Federated searching Advantages / benefits
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Federated searching: benefits for the users + The system can help the user to select appropriate sources.
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Federated searching: benefits for the users + The system can help in the process of authentication and authorization when this involves not only a simple recognition of IP-address of the user’s client computer, but when it involves user-id’s and passwords.
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Federated searching: benefits for the users + The need to know which particular database is suitable for a particular search is reduced, because several ones can be searched in one action.
☺
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Federated searching: benefits for the users + The users have to learn only 1 user interface for searching and only 1 search syntax, instead of a user interface and a search syntax for each database!
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Federated searching: benefits for the users + Saves the users time executing queries to various servers!
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Federated searching: benefits for the users + Can make users search and exploit databases that they would never use otherwise, that is without federated search system!
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Federated searching: benefits for the users + Useful, relevant, interesting items/references can be found/uncovered from unexpected, unknown, unfamiliar databases! This is mainly beneficial in the case of interdisciplinary subjects/topics.
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Federated searching: benefits for the users + Offers a consistent display of results in the output phase, (even though the original sources display results in various ways).
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Federated searching: benefits for the users + Some systems offer tools to refine display of the results; for instance »to dedupe very similar items in the result set, »to sort the results, »to rank the results, »to search within the result set, »…
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Federated searching: benefits for the users + Some systems offer interesting links from a retrieval result to various related sources or services (such as the full text or a document delivery service), using a link generator based on the OpenURL standard.
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Federated searching: benefits for the users + Some systems check for each retrieved bibliographic description if the corresponding full text is immediately available online and indicate this immediately to the user, on the fly.
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Federated searching: benefits for the users + Some systems further process the retrieved results and display them in an interesting way that is not offered by the searched original systems. For instance: »
Clustering of results according to — subject — age — availability of full text
»
Displaying the results in a graphical way
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Federated searching: benefits for the users So far so good !
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Federated searching Difficulties / challenges / problems / limitations
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Federated searching: difficulties / challenges / problems - Portal software tries to cope with several difficulties/challenges/problems/pitfalls that hinder the application of the “good idea”: The user does not notice most of these problems and shortcomings, because results from various databases are merged by the federated search system.
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Federated searching through scattered databases User User
User User
Federated search engine
Search engine
Database
Search engine
Database
Search engine
Database
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Federated searching: difficulties / challenges / problems - Searching in a target database may be restricted by the federated search engine to a particular field (for example: a restriction to words occurring in the title, because this is the default way of searching of that system) while this restriction is not present in other target databases. Furthermore, this is perhaps not explained in the user interface. This may lead to a lower recall, which is of course NOT desirable. Even worse, the user is perhaps not aware of this.
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Federated searching: difficulties / challenges / problems - How to deduplicate/dedupe/cluster very similar entries/results/items = near-duplicates, from various target sources? When is similar similar enough? Which entry/result/item to choose/select as the representative of a cluster of similar entries?
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Federated searching: difficulties / challenges / problems - How to provide some useful relevance ranking of search results/entries, even when the target databases can be quite different in type and quality, and even when no index is created in advance, just-in-case, well before the search action, like Google and other Internet search engines do.
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Federated searching: difficulties / challenges / problems - Powerful / sophisticated / refined forms of searching may not be applicable in a federated search. Example: limiting to a particular type of document, such as a therapy in medicine. This may cause a LOSS of time, instead of winning time.
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Federated searching through scattered databases User User
User User
Federated search engine
Search engine
Database
Search engine
Database
Search engine
Database
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Federated searching: difficulties / challenges / problems - Differences among target sources in the Internet application protocols that are applied normally, by default, for connection/communication and retrieval, such as »telnet »HTTP »proprietary, non-standard protocols »Z39.50, ISO239.50, SRU, and related protocols that are developed for federated-searching!
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Federated searching: difficulties / challenges / problems - Even when the target is compatible with a suitable set of protocols for standardised retrieval Z39.50, ISO239.50, SRU…, then difficulties can arise due to »poor implementations »incomplete implementations (the target may lack features supported by the protocol and by the software for federated searching) »variations in implementations
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Federated searching: difficulties / challenges / problems - When a suitable protocol can NOT be used and simple HTTP must be used for connection to the target source, and when simple HTML is used by the target source to present results, then the capture and analysis of the results by the federating search system is complicated and difficult and can be hindered by changes with time in the method of the presentation of results.
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Federated searching through scattered databases User User
User User
Federated search engine
Search engine
Database
Search engine
Database
Search engine
Database
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Federated searching: difficulties / challenges / problems - Various search engines may act in different ways! For instance: Is truncation of a word in a search query possible? Is limitation to a particular field possible? How can a federated search engine take these differences into account?
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Federated searching: difficulties / challenges / problems - A query with several words and without explicit Boolean operators can be interpreted in various ways by the various database retrieval systems. For instance, the retrieval software may apply the Boolean operator AND to combine all the query words, but it may also use OR. In the case that the federated search system does not take care of this well, then this may lead to lower recall and precision.
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Federated searching: difficulties / challenges / problems - When some special, non-standard, dedicated retrieval software is made available by a specific target source databases to offer special features to the user to exploit the database better than with a standard retrieval interface, then the source can probably not be exploited as well by the federated search system. Searches are reduced to the lowest common denominator.
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Federated searching: difficulties / challenges / problems - Differences in response time among the target sources. A slow response of a target source can hinder the final analysis and presentation of the results to the user.
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Federated searching through scattered databases User User
User User
Federated search engine
Search engine
Database
Search engine
Search engine
Database
Database
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Federated searching: difficulties / challenges / problems - Differences among target sources in the formatting/structuring of their database records in fields hinders - searching limited to a field (for instance the author field) - displaying selected fields only (such as the retrieved titles) - sorting of the displayed records on the contents of a particular selected field (such as author or publication date)
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Federated searching: difficulties / challenges / problems - Differences among target sources in the applied metadata schemes in the databases to improve retrieval, such as »classifications »taxonomies »thesaurus systems »ontologies This hinders the exploitation of the added value of such metadata.
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Federated searching: difficulties / challenges / problems - A user of a federated search system may perhaps incorrectly assume that ALL relevant databases are covered simply in 1 action, or that if a database is not included, then it must not be relevant/important. However, even a federated search system can only search a limited number of databases, so that perhaps some relevant databases are NOT covered.
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Federated searching: difficulties / challenges / problems - Students who rely on a federated search system may perhaps not learn about the important subject-specific databases in their field, so that when they have no access anymore to the same federated search system, they still do not know which database may help them in their research and how to use it well.
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Federated searching: difficulties / challenges / problems - Some databases are accessible only by a limited number of concurrent/simultaneous users from one organisation, as agreed in the licence and controlled by the authorization software of the database. When such a database would be included automatically in all or in many federated searches, then some users who really require access to that particular database may perhaps not be able to use that database.
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Federated searching: difficulties / challenges / problems - When a database is accessible by an unlimited number of concurrent/simultaneous users from one organisation, and when such a database would be included automatically in all or in many federated searches, from many organisations (even when the searcher does not have any particular interest in that database), then the retrieval system of that database may be overburdened. This is mainly a concern for information vendors, who must maintain servers with sufficient capacity.
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Federated searching: difficulties / challenges / problems - Some databases can NOT be included as a target database in a federated searching engine, because their owners/producers do not allow this. This is an important difficulty, because in this way interesting / valuable databases are perhaps not exploited by users who rely on federated searching. Even worse: one of the databases in this category is one of the biggest and important databases for the discovery of scientific documents AND is freely accessible through the direct, normal user interface: Google Scholar.
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Federated searching through scattered databases User User
User User
Federated search engine
Search engine
Database
Search engine
Search engine
Database
Database
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Federated searching: difficulties / challenges / problems - Users may be less impressed by a federated searching system than by the simple, common, familiar, famous Internet / WWW search engines, as response time is in most cases less impressive, due to differences as follows: - The computer hardware used by the systems - Slower distributed searching through several computer systems, versus faster searching through a more centralised computer database of a priori compiled records
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Federated searching: difficulties / challenges / problems - The evaluation of the quality of each search result from a federated search action may be more difficult than when each database is searched separately, because the user may be less aware of the limitations, strengths, selection criteria and aims of the individual, separate databases that offer each result. For instance, peer-reviewed articles from reputable scientific journals may be mixed with more popular and more biased, unscientific texts from trade literature.
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Federated searching Implementation
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Federated searching: local or remote hosting • The federated searching system can be developed and maintained »on a local computer in-house, or »hosted on a more distant, external, remote computer; this service is offered by some vendors of software for federated searching; partly outsourcing
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Federated searching: local hosting: scheme End Enduser user
☺ ☺
End Enduser user
☺ ☺
In-house In-houseportal portalfor for meta-searching meta-searching ==federated federatedsearching searching ==cross-database cross-databasesearching searching
information sources
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Federated searching: remote hosting: scheme End Enduser user
☺ ☺
End Enduser user
Externally Externallyhosted hostedportal portalfor for meta-searching meta-searching ==federated federatedsearching searching ==cross-database cross-databasesearching searching
information sources
☺ ☺
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Federated searching: local versus remote hosting • Remote hosting requires perhaps »a smaller initial investment in computer hardware and skilled personnel »less time investment in installation and maintenance of equipment and software
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Federated searching: tasks for the library Some roles/functions/tasks of the library related to federated searching: »of course providing a computer system for meta-searching »maintaining a list of target information sources that are appropriate in the framework of the particular library: —subjects covered by the target databases should be relevant —subscriptions must have been made by the library for access to the targets
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Federated searching: tasks for the library »grouping databases in groups that correspond to subject fields and offer these as pre-selections in the user interface of the federated search system »showing the system and its features to potential users »…
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Federated searching in a library WWW site? - Searching for books
- Opening hours
- Searching for articles
- Library services - Rules and regulations - Organisation of the library
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Federated searching in a library WWW site? - Searching for books
- Opening hours
- Catalog of this library
- Library services
- Other catalogs
- Rules and regulations
- Other book databases
- Organisation of the library
- Electronic books - Federated searching for books - Searching for articles
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Federated searching in a library WWW site? - Searching for books
- Opening hours
- Searching for articles
- Library services
- Databases to find articles
- Rules and regulations
- Electronic journals
- Organisation of the library
- Collective catalog of periodicals - Repositories of articles on the Internet and WWW - Federated searching for articles
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Federated searching in a library WWW site! - Find the information that you need - The catalog - Databases - Opening hours - Library services - Rules and regulations - Organisation of the library
To Toaafederated federatedsearch searchengine engine
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Federated searching: conclusion Federated searching - is a continuous challenge for developers of the sophisticated software and for the implementers in libraries and information centers - offers benefits for those end-users who are not enthusiastic to work with separate target source databases - does not eliminate the need for access to individual databases
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Libraries and information centres Putting federating searching in a wider context
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Federated searching + link generator user user
☺ ☺
reference reference federated federatedsearching searching
information information sources sources
full-text full-textdocument document!! menu menu
context-sensitive context-sensitive hyperlink hyperlinkgenerator generator
appropriate appropriate target target information information source source
database database about aboutlocal localsituation situation “knowledgebase” “knowledgebase”
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Federated search system and link resolver compared
Problem to be solved
Federated search system
Link resolver
How to bring a user to many information sources in 1 action?
!
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How to bring a user from some information to related information?
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!
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Putting the digital tools together in a library system user user
☺ ☺
library libraryWWW WWWsite site
catalogue(s) catalogue(s) of oflocal localholdings holdings
context-sensitive context-sensitive hyperlink hyperlinkgenerator generator
federated federatedsearching searching database database about aboutlocal localsituation situation “knowledgebase” “knowledgebase”
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Access to information sources: tools / methods / systems In sequence of priority:
1. Online library catalogue (for hard copy and digital documents) 2. Library web site 3. Link generator + “knowledgebase” 4.
Federated search system
5. …
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Libraries and information centres Good information sources about federated searching
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Some good information sources about federated searching Baer, William Federated searching: friend or foe? College & Research Libraries News, October 2004, pp. 518-519. Hofstede, Marten Portals op de pijnbank. Informatie Professional, 2002, No. 10, pp. 34-39. Jacso, Peter Thoughts about federated searching. Information Today, October 2004, pp. 17, 20. Joint, Nicholas Managing the implementation of a federated search tool in an academic library. Library Review, Vol. 58, No. 1, 2009, pp. 11-16. Linoski, Alexis and Walczyk, Tine Federated search 101. Library Journal Netconnect Summer 2008, pp. 2-5. Lockwood, Charles and Mac Donald, Patricia Implementation of a federated search system in the academic library: lessons learned. Co-published simultaneously in Internet Reference Service Quarterly, Vol. 12, No. ½, 2007, pp. 73-91 and in Federated search: solution or setback for online library services (edited by Christopher N. Cox) The Haworth Information Press, 2007, pp. 73-91. Available online from: http://irsq.haworthpress.com McHale, Nina Accidental federated searching: implementing federated searching in the smaller academic library. Co-published simultaneously in Internet Reference Service Quarterly, Vol. 12, No. 1-2, 2007, pp. 93-110 and in Federated search: solution or setback for online library services (edited by Christopher N. Cox) The Haworth Information Press, 2007, pp. 93-110. Available online from: http://irsq.haworthpress.com Noerr, Peter Scaling the digital divide: how interoperable systems are making information more accessible. In proceedings of the International Conference on Digital Libraries 2004: knowledge creation, preservation, access, and management, ICDL 2004, in Habitat Centre, New Delhi, India, 24-27 February 2004, Volume 1, 517 pp. New Delhi : TERI, The Energy and Resources Institute, 2004, ISBN 81-7993-029-7, pp. 66-68. Reiss, Kevin SRU, Open Data and the future of metasearch Co-published simultaneously in Internet Reference Service Quarterly, Vol. 12, No. ½, 2007, pp. 369-386 and in Federated search: solution or setback for online library services (edited by Christopher N. Cox) The Haworth Information Press, 2007, pp. 369-386. Available online from: http://irsq.haworthpress.com Sadeh, Tamar To Google or not to Google: metasearch design in the quest for the ideal user experience. [online] In: Proceedings of the ELAG 2004 Conference, May 2004. Available from: http://www.elag.org/ [cited 2004] Sadeh, Tamar Transforming the metasearch concept into a friendly user experience. Co-published simultaneously in Internet Reference Service Quarterly, Vol. 12, No. ½, 2007, pp. 1-25 and in Federated search: solution or setback for online library services (edited by Christopher N. Cox) The Haworth Information Press, 2007, pp. 1-25. Available online from: http://irsq.haworthpress.com Tennant, Roy The right solution: federated search tools. Library Journal, June 15, 2003, p. 28. Webster, Peter M. Challenges for federated searching. Co-published simultaneously in Internet Reference Service Quarterly, Vol. 12, No. ½, 2007, pp. 357-368 and in Federated search: solution or setback for online library services (edited by Christopher N. Cox) The Haworth Information Press, 2007, pp. 357-368. Available online from: http://irsq.haworthpress.com
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