Metadata Schema Transformation Services


Many researchers in the LIS community recognize the need to lower the barriers to the management of digital resources by implementing some measure of interoperability among metadata standards. They have proposed a wide range of solutions, including crosswalks, translation algorithms, metadata registries, and specialized data dictionaries. Yet despite some genuine advances, it is still difficult to identify the common elements in different metadata standards and put this information to use in systems that resolve differences between incompatible records.

Background

The goal of the Metadata Schema Transformation project is to develop data models and software tools that ease the task of translating between metadata standards, bridging the gap between analysis and execution. Our work focuses on technical implementations of the crosswalk, the object that distinguishes metadata translation from more routine types of data and format conversion.

Crosswalks are typically presented as tables of equivalent elements in two standards, such as MARC 245 $a and Dublin Core Title or ONIX Contributor/PersonName and MARC 100 $a. Though the equivalences may be inexact, they represent an expert's judgment that the differences are immaterial to the successful operation of a software process that involves records encoded in the two standards.

Crosswalks are all too often implemented in an ad-hoc fashion when an application needs a particular conversion. Though this strategy is expedient in the short term, it eventually produces silos, duplicated work, and unpredictable results across different systems.

We avoid these problems by designing a self-contained crosswalk utility that can be called by any application that must translate metadata records. In our implementation, the translation logic is executed by a dedicated XML application called the Semantic Equivalence Expression Language, or Seel, a language specification and a corresponding interpreter that transcribes the information in a crosswalk into an executable format.

These components are packaged as The Crosswalk Web Service, which optimizes change management and dramatically reduces redundant effort.

    Impact

    In addition to the research results reported in our presentations and publications, the Crosswalk Web Service is now a production system that has been incorporated into the following OCLC products and services.

    Scope

    Our work focuses on the conversion of standards that describe bibliographic metadata. But the tools we have developed are generic and can be applied to metadata that is managed by other communities of practice.

    Methodology

    System building and evaluation.

    Primary Audience

    Since this project focuses on infrastructure improvements, it is intended to benefit software developers who work in library technical services departments and must manage collections of metadata.

    Next steps

    1. Create an instance of the Crosswalk Web Service that converts authorities metadata.
    2. Design and implement utilities that interact with the Crosswalk Web service to manage ephemeral process data and convert from one data encoding to another.

    Outputs

    Research reports, articles and key presentations by project team

    Most recent updates: Page content: 2010-04-09 Prototype: 2008-07-22

    Lead

    Jean Godby

    Team Members

    Devon Smith

    Eric Childress

    Larry Evans

    Jay Stuler, Technical Intern (2000 - 2006)

    Crosswalk Demo

    The OCLC Crosswalk Web Service Demo is available.

    The public demo calls an instance of the Crosswalk Web Service that resides outside OCLC’s firewall. It translates to and from the following formats:

    Dublin Core, MARC-XML, MARC-2709, and MODS.

    Users need to download a thin client containing the web service API. After following some simple instructions (listed on the download page), they will have a software module that can be incorporated into their own applications.

    This activity is a part of the Metadata Management theme.

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