Several OAI service providers (Harvesters) are coming up
providing cross-search services by harvesting metadata from OAI
compliant repositories. OAI facilitates quick discovery of content and
free exchange of information among repositories through Service
Providers (Harvesters). In order to achieve interoperability in their
operations, Service Providers need to incorporate a generalized set of
search and browse features in their search interface. Few parameters are
drawn to compare the search and retrieval features of harvesters and
arrived at a useful checklist for Service Providers to achieve
homogeneity and standardization while designing their search interfac

Indrani, V.

Thulasi, K.

English

Librarians' Digital Library

ARD Prasad & Devika P. Madalli (Eds.): ICSD-2007, pp. 472-482, 2007 
A Comparative Study of the Search and Retrieval 
Features of OAI Harvesting Services  
 
 
Indrani V 1 and Thulasi K. 2 
 
1 Information Centre for Aerospace Science and Technology,  
National Aerospace Laboratories, Bangalore, Karnataka India 
indrani@css.nal.res.in 
 
2 National Centre for Science Information  
Indian Institute of Science  
Bangalore, Karnataka India 
thulasi@ncsi.iisc.ernet.in   
 
 
Abstract. Several OAI service providers (Harvesters) are coming up 
providing cross-search services by harvesting metadata from OAI 
compliant repositories. OAI facilitates quick discovery of content and 
free exchange of information among repositories through Service 
Providers (Harvesters). In order to achieve interoperability in their 
operations, Service Providers need to incorporate a generalized set of 
search and browse features in their search interface. Few parameters are 
drawn to compare the search and retrieval features of harvesters and 
arrived at a useful checklist for Service Providers to achieve 
homogeneity and standardization while designing their search interface  
 
Keywords: Service Providers Features; Comparative Study of OAI 
harvesting services; Metadata fields in OAI harvesting 
 
1    Introduction 
Objective of this article is to compare the features supported by the service 
providers (Harvesters) for searching, browsing and presentation of results. 
Open Archive Initiative (OAI) is a protocol. This is all about moving metadata 
around and aim to focus on interoperability. OAI has a protocol to harvest 
metadata from other archives. OAI divides the world into two participants one 
is metadata providers called as data providers and another one has harvesters 
called as service providers. 
Data providers refer to entities that possess data and metadata and are willing 
to share metadata with others via well-defined OAI protocols. Service 
Providers are entities that harvest metadata from Data providers in order to 
provide higher-level service to users. 
A Comparative Study of the Search and Retrieval… 473
Search and Retrieval features are used by the Archives (Data providers & 
Service providers) either to retrieve or to expose their metadata. 
This article compares the search and retrieval features of the OAI service 
providers. 
2 Aim and Scope  
OAI stresses on interoperability in technology and its operations as well and 
also it is equally important for Service Providers (Harvesters) to incorporate a 
generalized set of search and browse features in their search interface, to make 
it more interoperable among service providers, repositories and users. 
List of criteria is identified and classified under broad headings a. Purpose 
and Scope b. Software c. Volume and Growth d. Usage e. Metadata f. Search 
and Browse g. Display Options and h. Additional Services. Based on the list 
of criteria, a comparative study of the Search/Browse Interface of a few 
important Service Providers was carried out, in relation to searching, 
browsing and presentation of results. Few service providers like ARC, 
OAIster, SAIL, Archon, Metalis and Citebase among other registered service 
providers that exist today are compared for the study. Arc, OAIster and SAIL 
are leading service providers harvesting metadata from several archives 
covering major subject disciplines. Citebase include citation information 
besides standard metadata elements to provide citation search services. 
ARCHON and Metalis are two subject specific Service Providers in Physics 
and Library science respectively.  
The basic idea is to bring out a list of parameters for comparison of search and 
browse features with suggestion for Service Providers to include the same in 
order to  
a) To achieve homogeneity and standardization while designing their 
search interface. 
b) Help users to search and identity resources efficiently and effectively 
while searching from different Service Providers search interface.   
Also a checklist that would be useful for Service Providers, while designing 
their search/browse interface, and would also facilitate quick access and 
efficient retrieval of records. This could be useful to current and prospective 
service providers in improving or designing their search interface who plan to 
set up new OAI-based Service Provider 
Indrani V. & Thulasi K. 474
Search and Retrieval 
Features 
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     1. Purpose:       
           1.1 Cross Archive  
yes yes yes yes yes yes 
           1.2 Citation based     
yes 
 
yes 
 
   2. Scope:   
 
    
2. 2.2.1 Discipline based 
harveharharvesting  
     
yes 
 
yes 
2.2 Multiple discipline 
harvesting 
 
yes 
 
yes 
 
yes 
 
yes 
  
2.3 Resource type harvesting          
       2.3.1TechnicalReports       
2.3.2 Patents       
        2.3.3 Thesis       
        2.3.4 Others       
        2.3.5 All types yes yes yes yes yes yes 
   3. Software:       
          3.1. Own Software yes  yes yes yes yes 
               3.1.1Available as      
 open source 
yes  yes yes yes yes 
          3.2 Commercial 
 Software 
 yes     
          3.3 Database       
                3.3.1 MySQL yes yes yes yes yes yes 
                3.3.2 Oracle yes      
A Comparative Study of the Search and Retrieval… 475
          3.4 Platform       
                3.4.1Linux  
 Operating System 
yes yes yes yes yes yes 
                3.4.2 Java yes yes yes yes yes yes 
                3.4.3 Perl yes yes  yes  yes 
    4. Volume & Growth       
         4.1 Frequency of  
  Harvesting 
      
               4.1.1 Weekly           yes yes yes  yes 
               4.1.2  Bi weekly yes    yes yes 
   5. Service Usage:       
   5.1 No. of Searches, 
  Records 
  yes    
   5.2 Most  accessed 
  archives 
  yes    
   5.3 Most accessed  
  clients 
  yes    
   6. Metadata:       
        6.1 Unqualified Dublin 
  Core 
yes yes yes yes yes yes 
  7. Search and Browse:       
       7.1 Simple Search yes yes yes  yes yes 
       7.2 Advanced Search yes  yes yes yes yes 
            7.2.1 Field based       
                   7.2.1.1  
  Author/Title 
yes yes yes yes yes yes 
                   7.2.1.2 Title yes yes  yes yes yes 
                   7.2.1.3 Abstract yes yes yes yes yes yes 
                   7.2.1.4 Subject  yes     
                   7.2.1.5 Archive yes yes yes yes yes yes 
Indrani V. & Thulasi K. 476
          7.2.2 Phrase searching yes yes   yes yes 
          7.2.3 Boolean yes yes yes yes yes yes 
          7.2.4 Equation search     yes  
          7.2.5 Process Result 
  Set 
yes yes   yes  
            7.2.6 Duplicate  
  detection 
      
      7.3 Filter option       
            7.3.1 Archive       
                  7.3.1.1 All  
  Archives 
yes  yes  yes yes 
                  7.3.1.2 Archive 
   name 
yes  yes  yes yes 
            7.3.2 Subject yes  yes  yes yes 
            7.3.3 Resource type yes yes   yes yes 
            7.3.4 Date Stamp yes  yes  yes yes 
            7.3.5 Discovery Date yes  yes  yes yes 
     7.4 Browse       
            7.4.1 Archive yes yes   yes  
            7.4.2 Title        
            7.4.3 Author   yes    
            7.4.4 Any  
 other/Deposit date 
  yes    
     7.5 Citation Search       
            7.5.1 Citation Author    yes   
            7.5.2 Paper    yes yes  
            7.5.3 Year    yes   
     7.6 Search History       
            7.6.1 Saved Searches   yes    
      7.7 Annotations     yes  
A Comparative Study of the Search and Retrieval… 477
8. Display Option:       
     8.1 Sorting:       
            8.1.1 Title yes yes   yes yes 
            8.1.2 Author  yes    yes 
            8.1.3 Date stamp  yes  yes   
            8.1.4 Discovery date yes yes  yes yes yes 
            8.1.5 Archives yes    yes  
            8.1.6 Subject yes    yes  
            8.1.7 Relevance  
  Ranking: 
 yes  yes   
                   8.1.7.1 Hit  
  frequency 
 yes     
                   8.1.7.2 Weight 
  Hit    frequency 
 yes     
                   8.1.7.3 Citation, 
  Hits, Score 
   yes   
     8.2 Display Results       
            8.2.1 Archives yes yes yes  yes  
            8.2.2 Summary yes  yes yes yes yes 
                   8.2.2.1 Title yes  yes yes yes yes 
            8.2.3 Detail yes yes yes yes yes yes 
                   8.2.3.1Author yes yes yes yes yes yes 
                   8.2.3.2Title yes yes yes yes yes yes 
                   
8.2.3.3Contributor 
 yes     
                   8.2.3.4Year  
  (Discovery) 
yes yes yes yes yes yes 
                   8.2.3.5Publisher yes yes yes yes  yes 
                   8.2.3.6Resource 
   type 
yes yes yes yes  yes 
Indrani V. & Thulasi K. 478
                   8.2.3.7Resource 
   Format 
yes yes yes    
                   8.2.3.8Language  yes yes   yes 
                   8.2.3.9Abstract yes yes yes yes yes yes 
                   8.2.3.10Subject yes yes yes yes yes yes 
                   8.2.3.11 URL yes yes yes yes yes yes 
                   8.2.3.12 Note  yes     
               8.2.3.13Record 
   ID 
  yes yes yes  
                   8.2.3.14 Citation 
   info 
   yes yes  
                   8.2.3.15 Similar 
 Authors (clickable) 
   yes yes  
                   8.2.3.16 Similar    
 Subjects (clickable) 
yes    yes  
                   8.2.3.17  
  Institution 
 yes yes    
9. Additional services:       
    9.1 Alerting services   yes    
    9.2 Act as data  
 provider 
yes yes     
       9.2.1 base URL yes yes     
Table 1 A comparative study of the Service Providers is made based on the list of 
criteria, with results 
Note: Blank cell in the table indicates it is  Not Supported 
A Comparative Study of the Search and Retrieval… 479
Analysis of Service Providers based on the above comparison of criteria  
Presently, Archon and Citebase offer citation search services among others. 
Arc and OAIster act as both Data Providers and Service providers.  These 
Service Providers harvest all resource types like journals, technical reports, 
and conference proceedings and do not concentrate on any specific ones. 
While OAIster and Citebase have single search interface, the rest support both 
simple and advance search interface. Citebase include citation searching and 
Archon Equation searching. Archive names in the dropdown menu should be 
arranged strictly in alphabetical order. Just as corresponding Archive Set 
values get displayed with particular Archive, so also corresponding subject 
should be displayed instead of subjects included in all Archives, thus reducing 
search time. Citebase includes query-processing time with response being 
pretty fast. None of them use Proximity operators like WITH, NEAR which 
increases precision in searching.  It is useful to include Browsing by broad 
topical categories or Subjects, Resource types besides Institutions or Deposit 
date or Author. Search within selected browse categories will be useful as 
provided by SAIL and Metalis. Currently there is a limit in the number of 
records for Grouping or Sorting. Citebase and Metalis have no grouping of 
archives for displaying records. Only SAIL supports Saving Search history for 
setting up Alerts, Saving records using standard bibliographic tools, viewing 
latest updates of records harvested and offers detailed Usage Statistics. 
Archon’s Annotations field is unique enabling users to make some notes on 
the respective record. Arc, Archon, Citebase and OAIster support relevance 
ranking of results. Archon’s Linking is extensive compared to others. It 
includes, author with links to his other articles, Show Equations(all equations 
from the result set is shown), Similar subject (all other articles in the current 
result set with same subject), Citation Links showing list of citing references 
as well as cited references. Arc, Archon, Metalis and SAIL provide extended 
services through OpenURL field, by providing links to other services and 
metadata formats. None of these Service Providers are able to detect 
Duplicate records while harvesting from various Data Providers. 
There is no uniformity in rendering values for metadata elements by Archives. 
For example, Arc assigns URL instead of Institution name for metadata 
Source DL unlike others who assign the repository name without link. 
OAIster renders values for Resource type and resource format 
interchangeably. Some archives have names like Yea, tkn, pkp, that can be 
expanded to be more meaningful and explicit. Thus values for Metadata 
Subjects, Set, Resource type, Resource formats and Deposit date, Discovery 
date, Date, Harvest date, Datestamp, Accession Date among Archives have 
not been normalized correctly by Service Providers. [5] 
Indrani V. & Thulasi K. 480
Checklist for Service Providers 
Based on the analysis of search and browse interface of these Service 
Providers, The following checklist that may be considered by other service 
providers, while designing their search/browse interface.  
• Navigation Links - Navigation in the search/browse interface can 
include links to Home page, Simple search, Advanced Search, 
Browse, Alerting services, Usage Info, Help/FAQ(Query examples), 
Latest Updates(Weekly, Monthly, 3 months updates), Related links to 
other service providers, Administration( to include registration for 
Login/user id and others), Additional information like OAI related 
institutions,  Reference articles on OAI, Trouble shooting tips, 
Contact and Copyright information 
• Browse Interface - Browse features can include browse by archive, 
institution, deposit date, author, subjects or broad topical categories, 
resource type, equations/formulae, latest updates (weekly, monthly)  
• Simple Search Interface – Searching on Author, Title and 
Abstract/Description 
• Advanced Search Interface - Searchable Fields: Archive, Title, 
Abstract, Author (permuted names), Subject, Resource type, Date 
stamp, Discovery date, Archive set, Institution hosting archives; 
Besides keywords, should also support Equations/Formulae based 
searching; Search within multiple archives to be allowed; Search 
based on broad standard subjects/Topical categories; Combining 
search to Title and Abstract fields in order to retrieve only those 
records with abstracts; Use of Boolean operators AND, OR NOT 
within a field as well as across the fields; Besides author or creator, 
contributor and others can also be included based on the type of 
resource; Lateral searching of records from the search result; Case-
sensitivity/Capitalization ignored, Word variations supported, 
punctuations to be ignored, parenthesis for grouping words; Natural 
language searching as in Goggle can be considered; Filtering/Limiting 
Fields: Filtering option : limiting to language, resource type. 
• Result set processing options - Ability to refine the search made or 
build the searches, inclusion of ‘Search summary box’ 
• Sorting Fields - Sorting of records by Archive, Discovery year, 
Subject, proximity, institution frequency, Title, Author, Date, 
Relevance ranking  
• Hit frequency or Weighted hit frequency; Default sort order can be 
title; No limit for sorting.  
• Display/Saving records - Customizing Display of no. of results per 
page; Select/Mark/Unmark the records for display or for 
saving/export  to some bibliographic management tool; Highlighting 
A Comparative Study of the Search and Retrieval… 481
of search words in results; Title and KWIC among other display 
formats; Make HTML embedded in search results records viewable 
and linkable; Ability to save records during a session, download and 
email them; Ability to view all records without restrictions 
• OpenURL and Z39.50 compliancy for use with other federated search 
engines 
• Usage Statistics - Include list of most accessed archives, most 
important clients, no. of simple, advanced searches done, browse 
pages accessed annually  
• Duplicate records detection – Implement automatic checking of 
duplicate records by Service Providers while harvesting metadata 
records 
• Standardization of Archive names - Archive name followed by 
Institution hosting the same as well as Broad subject category will 
make it more explicit and meaningful 
• Alerting services - Alerting registered users with latest records based 
on saved search query; List of latest institutions/archives harvested 
monthly/fortnightly 
• Cross-archive citation search service – Include Linking of references 
for each article. 
• Help - Context-specific help with Query Examples will be more 
useful/ Detailed FAQ/Trouble Shooting Tips etc. 
3 Conclusion  
Based on the study, observation is made that the search interface of OAI 
Service Providers has few features as compared to extensive search features 
incorporated in bibliographic databases. This may be because the resources in 
the archives are freely accessible unlike licensed bibliographic databases. 
Users always tend to do quick and general searches rather than do a perfect 
search. The more specific the search features adopted by each Service 
provider, the more difficult for the users, to understand and perform searches. 
Since they provide access to collection in the archives that are decentralized as 
well as each archive following their own rules in rendering information 
related to various metadata fields, users face difficulty in performing efficient 
search and retrieval from individual Service Providers. Standardization in 
rendering information for all metadata elements is also very essential. The 
archives included by individual Service Providers can be mutually exclusive. 
Eg General/Comprehensive (OAIster or Arc), Subject wise (Metalis), 
Resourcetype wise (NCSTRL), Country wise Service Providers etc. This will 
reduce unnecessary proliferation of Service Providers as well as prevent 
different Service providers wasting their resources in harvesting the same 
records from same set of archives. The archives also need to submit only to 
Indrani V. & Thulasi K. 482
one specific Service Provider based on the nature of their resources, instead of 
registering with multiple Service Providers, as is the case now. This will also 
help users enormously by saving their search time. Since Service Providers 
facilitate one point access to highly valuable information residing in various 
archives harvested by them, the search/browse interface should be as simple 
and at the same time include all the necessary search and retrieval features, so 
users can carry out their searches efficiently and effortlessly. 
References 
[1]  Liu, X., Maly, K., Zubair, M. (2001). Arc - An OAI Service Provider 
for     Digital Library Federation. D-Lib Magazine. 7.     
        http://www.dlib.org/dlib/april01/liu/04liu.html 
[2]  Hitchcock, S. (2002). The Open Citation Project Final (Year 3) 
Report to JISC. http://opcit.eprints.org/finalreport/final-report111.pdf 
[3]  Liu, X., Maly, K., Zubair, M. (2002). Federated Searching Interface 
Techniques for Heterogeneous OAI Repositories. Journal of Digital 
Information. 2. http://jodi.tamu.edu/Articles/v02/i04/Liu/ 
[4]  Arc. http://arc.cs.odu.edu 
[5]  METALIS. http://metalis.cilea.it/index.html 
[6]  OAIster. http://oaister.umdl.umich.edu/o/oaister/ 
[7]  SAIL-eprints. http://eprints.bo.cnr.it/ 
[8] Indrani, V, guided by Rajasekhar T B, Thulasi K, Filbert Minj (2005). 
Comparison of Search and Retrieval features of OAI Harvesting   
Services. Major project report submitted in partial fulfillment for the 
Training Programme in Information and Knowledge Management, 
National Centre for Science Information, Indian Institute of Science, 
Bangalore. 


A comparative study of the search and retrieval features of OAI harvesting services

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A comparative study of the search and retrieval features of OAI harvesting services

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