1. University of Illinois at Urbana-Champaign OAI Alpha Experiences
Timothy W. Cole
Thomas G. Habing
Grainger Engineering Library Information Center
30 March 2001

2. OAI Metadata -- Univ. of Illinois at UC
Context & Motivation
Origins of Open Archives Initiative
E-Print Archives, Efficient Dissemination of Content
1999 Santa Fe Convention
Metadata Key to Several UIUC Projects
DLI / D-Lib Test Suite
Digital Imaging & Multimedia Technology Initiative
Archives & Special Collections Finding Aids (EAD)
Kolb-Proust Archive (TEI)
Increasing Reliance on Digital Resources
Cross-Repository Discovery of Information Resources
Enhanced Sharing / Linking Between Resources
The Open Archives Initiative develops and promotes interoperability standards that aim to facilitate the efficient dissemination of content. The Open Archives
Initiative has its roots in an effort to enhance access to e-print archives as a means of increasing the availability of scholarly communication. Continued support of this
work remains a cornerstone of the Open Archives program. The fundamental technological framework and standards that are developing to support this work are,
however, independent of the both the type of content offered and the economic mechanisms surrounding that content, and promise to have much broader relevance
in opening up access to a range of digital materials. As a result, the Open Archives Initiative is currently an organization and an effort explicitly in transition, and is
committed to exploring and enabling this new and broader range of applications. As we gain greater knowledge of the scope of applicability of the underlying
technology and standards being developed, and begin to understand the structure and culture of the various adopter communities, we expect that we will have to
make continued evolutionary changes to both the mission and organization of the Open Archives Initiative.
30 March 2001
OAI Metadata -- Univ. of Illinois at UC

3. OAI Metadata Harvesting Protocol
Key Concepts
Repository, Record, Identifier, Datestamp, Set
How It Works
HTTP Request: Use GET or POST To Request Metadata
HTTP Response: XML or, if an error, HTTP Status-Code
Flow Control: resumptionToken and Retry Status-Code
Metadata Schemas: DC is required, but others allowed
Tools and Support
30 March 2001
OAI Metadata -- Univ. of Illinois at UC

4. OAI Metadata Harvesting Protocol
Verbs
Identify: return administrative information about a repository
ListMetadataFormats: return list of metadata formats supported by repository, or for specific record in repository
ListSets: return a list of sets supported by the repository
GetRecord: return 1 record given an identifier & format desired
ListIdentifiers: return a list of record identifiers, optionally filtered by date or set
ListRecords: return a list of records in a given metadata format, optionally filtered by date or set
Can’t Retrieve/Filter by Subject or Keyword
30 March 2001
OAI Metadata -- Univ. of Illinois at UC

5. OAI Metadata Harvesting Protocol
Implementation Issues
Metadata Acquisition and Storage: Database or File System
Metadata Formats: Mapping to the Required OAI_DC format, plus optionally any other community-specific metadata formats
Set Definition -- Hierarchical or Overlapping
Flow Control -- How to Keep From Being Swamped
Limited Requirement to Maintain Inventory of Deleted Records (status=‘deleted’)
Access Control or User Authentication, if required
About Block Can Describe Conditions of Use
30 March 2001
OAI Metadata -- Univ. of Illinois at UC

6. Metadata We Contributed (Alpha)
D-LIB Scientific / Technical Journal Articles
Articles from AIP & APS publications (~5,500 objects)
Metadata in XML (RDF, DC, Local Namespaces)
Implemented Access & Authorization Features
Added & Updated Metadata Records During Test
Digital Imaging and Media Technology Initiative
Digital Cultural Heritage Community -- Digitized Images for Elementary Grades Curricula (~500 objects)
Metadata in Flat Database Structure
Planned Future Additions
Digitized Historical Aerial Photos of Illinois
EAD Finding Aids for Manuscript Archive Collections
30 March 2001
OAI Metadata -- Univ. of Illinois at UC

7. Computing Environment
MS Windows NT 4.0 Operating System
MS Internet Information Server 4.0
Active Server Pages (VBScript & JScript)
MS SQL Server 7 and MS Access 97
D-Lib XML Data Uploaded Using Visual Basic & MSXML Parser / DOM Implementation
Future Plans
Windows 2000, IIS 5, SQL & Access 2000
XML Extensions for MS SQL Server
30 March 2001
OAI Metadata -- Univ. of Illinois at UC

8. Assumptions / Groundrules
Each Object Member of 1 and Only 1 Set Hierarchy
Flow-Control Exclusively Using resumptionTokens
Non-ASCII Characters May Be Included
UTF-8 and hexadecimal character references
Not Investigated During Alpha Testing
Mechanisms to Maintain Server-Side Statefulness
Redirection Using HTTP Headers
Status=‘Deleted’ (Attribute of recordType)
Alternative Metadata Formats (e.g., DCQ or Formats Allowing Embedded Markup from XHTML Namespace)
30 March 2001
OAI Metadata -- Univ. of Illinois at UC

9. OAI Metadata -- Univ. of Illinois at UC
30 March 2001
OAI Metadata -- Univ. of Illinois at UC

10. OAI Metadata -- Univ. of Illinois at UC
30 March 2001
OAI Metadata -- Univ. of Illinois at UC

11. OAI Metadata -- Univ. of Illinois at UC
System Architecture
Metadata Maintained in Relational DB
Root table & secondary tables (e.g., 1 each DC category)
Additional tables for set descriptions & supported schemas
Stored Procedures Map DB Fields to Schema Elements De-couples Database Schema from Metadata Schema(s)
OAI Responses Built Dynamically
Use ASP To Query DB & Build Response Each OAI Verb becomes a Case Statement XML Syntax & Semantics Explicitly Coded in ASP HTTP Errors Constructed Using ASP Built-in Objects Authentication & Access Controls in global.asa Maintained Separate Log Files
30 March 2001
OAI Metadata -- Univ. of Illinois at UC

12. OAI Metadata -- Univ. of Illinois at UC
Database Schema
About object_id date_stamp sets
1:n
1:n
DC_Creator object_id creator
DC_Subject object_id subject scheme
DC_Title object_id title
30 March 2001
OAI Metadata -- Univ. of Illinois at UC

13. OAI Metadata -- Univ. of Illinois at UC
Evaluative Comments
Given Metadata, Minimal Effort to Implement OAI
2 to 4 Weeks to Design DB & Upload Data
2 to 4 Weeks to Implement OAI Provider Service
Generic, Modular Technology for Sharing Metadata
Usable for Both Vertical & Cross-Domain Applications
Boon to Institutions (like libraries) that Have Multiplicity of Diverse Collections
More Work to Do on Harvest Service Applications
How Powerful is Search Against LCD Metadata Schema
Cross-Schema Mapping Issues Still Remain
Local Linking & Presentation Issues Remain
30 March 2001
OAI Metadata -- Univ. of Illinois at UC

14. OAI Metadata -- Univ. of Illinois at UC
Possible Future Work
Alternative System Architectures
Single Table DB Schema for All Metadata Content
File-System Based Metadata Storage Approach
Exploit MS XML Front-End to SQL Server
Turnkey OAI Provider Service Applications
E.g., Generic ASP with Template MS Access Database
OAI Metadata Brokerage Services
OAI Metadata Harvesting Service for Manuscript Archives & Cultural Heritage Information
30 March 2001
OAI Metadata -- Univ. of Illinois at UC