Interchange (data format standards)
There is an increasing need for museums to exchange their data with each other (for example, for exhibition planning or research), for museums to exchange data internally (for example, among departments, applications or platforms) and also for museums to include their data in collective resources. There are several ways that museums can exchange or share cultural heritage data, such as:
- import/export and transfer of data files and
Standards have been developed to make these activities possible.
- Meaningful data exchange
Meaningful data exchange
Most collections management software has the capability to export or import data in a number of formats. This makes it possible for a museum to export their collections management data for transfer to another system and/or organization. But the challenge is to transfer the data without losing any of the "meaning" or precision of the data in the process. Much of this meaning is not inherent in the actual data but is in the definitions of the data elements used by the system and the relationships between data elements. For example, museum collections data may contain a large number of personal names and dates, but unless these data elements (such as creator name, creator birth date, cataloguer name, collector name, collection date) are described and the relationships between the fields are clear, the data are not very useful.
There are a variety of tools, standards and protocols to assist with the exchange of cultural heritage data. These tools are used to define a structure for the various data elements and also to exchange the data along with the relationships.
Conceptual Reference Model
CIDOC Conceptual Reference Model (CIDOC CRM)
"The CIDOC Conceptual Reference Model (CRM) provides definitions and a formal structure for describing the implicit and explicit concepts and relationships used in cultural heritage documentation" and "is intended to be a common language for domain experts and implementers to formulate requirements for information systems and to serve as a guide for good practice of conceptual modelling." The scope of the CIDOC CRM is very broad and is intended to cover all information required for the documentation and management of cultural heritage. It contains 86 classes and 137 unique properties. CIDOC CRM is "intended to promote a shared understanding of cultural heritage information by providing a common and extensible semantic framework that any cultural heritage information can be mapped to. In this way, it can provide the 'semantic glue' needed to mediate between different sources of cultural heritage information, such as that published by museums, libraries and archives." CIDOC CRM has an event-centred approach to the representation of metadata (such as creation and use), which is now regarded as the most flexible way to model cultural heritage data. An encoding of the CIDOC CRM is provided in RDF Schema, but it is possible to represent it in other ways. It is recognized as an ISO standard: ISO 21127:2006. CIDOC CRM instances can be encoded in RDF, XML, OWL, etc. CIDOC CRM has been harmonized with FRBR (which deals with Functional Requirements for Bibliographic Records).
(Extensible Markup Language) can be used to allow information systems to share structured data. XML (and the community-specific standards based on it) is useful for sharing data between applications, because the data contain tags that describe what the data represent. XML provides a way to exchange not only the data, but also the meaning inherent within the data structure and relationships. Increasingly, XML is offered as an export option with commercial collections management software. Any structured museum data can be encoded in XML.
XML schemas for museums
There are several XML-based, "community-specific" standards which have been developed to facilitate the exchange of museum and cultural heritage data. Some important XML schemas that have been developed specifically for museum data include:
Lightweight Information Describing Objects (LIDO)
LIDO (Lightweight Information Describing Objects) is an XML harvesting schema intended to transfer data from museum collections databases to multilingual data aggregations (such as Artefacts Canada) and for sharing museum data on the web. LIDO can represent the full range of descriptive information about museum objects and can be used for museum data of many disciplines (for example, art, cultural and natural science data). LIDO is the result of an international collaboration based upon CDWA Lite and museumdat schemas and is compliant with CIDOC CRM and aligned with SPECTRUM. Some collections management software systems are able to export LIDO records, enabling easier interchange. LIDO was announced in late 2010. It is available in English only.
CDWA-Lite XML Schema
CDWA Lite is an XML schema to describe a format for core records for works of art and material culture. CDWA Lite is based on the Categories for the Description of Works of Art (CDWA), a metadata standard developed by the Art Information Task Force (AITF). CDWA Lite records are intended for contribution to union catalogues and other repositories using the Open Archives Initiative (OAI) harvesting protocol. Because of its focus on core records, CDWA deals with only a subset of the data elements contained in CIDOC CRM, and it is much simpler. CDWA Lite has 22 elements; 9 of these are required. In 2010, Lightweight Information Describing Objects (LIDO) was created by harmonizing the CDWA Lite and museumdat schemas. Available in English only.
Regardless of whether a museum is exchanging data in tab-delimited format, XML or another format, if the structure of the data source is different from the structure of the target database, data mapping will have to be done to make sure the data are interpreted properly in the new system.
Sometimes this mapping is done directly between the two data systems. For example, museums that contribute to Artefacts Canada can map their fields to the Artefacts Canada fields using a simple web interface, and then upload their data in tab-delimited or other formats. This mapping process allows museums to match each element from their local system to one or more elements within the Artefacts Canada database, so that regardless of what system or metadata standard the museum uses, data that the museum upload to Artefacts Canada are properly interpreted and displayed within the national database.
Recently, there have been developments to make mapping of cultural heritage data a more automatic process. Instead of mapping between local data models on a case-by-case basis, mapping everything to a common standard facilitates exchange. For example, data from a source database are mapped to a standard, such as CIDOC CRM, and data are exported in CIDOC CRM XML so that other systems that comply with this standard can interpret and use this data without loss of meaning or precision.
As an alternative to exporting and transferring files to another organization or service, museums can also choose to expose their data for harvesting. In this scenario, the museum posts their data in some web-accessible location (either secured for limited access or openly accessible) in a standard format, and the data can be "harvested" by others, following standard protocols. In some cases, the exposed data are harvested and loaded into other systems; in other cases, the exposed data are merely queried, and the results are used by remote systems. Usually, data to be harvested are encoded in XML and can be shared using metadata harvesting protocols and tools such as:
Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH)
The OAI protocol is a potential means for museums to make their databased content more accessible on the Internet, so they can more easily participate in distributed "portal" services and re-purpose their collections management data. OAI defines a protocol both for metadata harvesting and for exposing OAI-compliant metadata to be harvested. A museum that wanted to exchange data using the OAI protocol would create an OAI-compliant data repository by "exposing" their data in XML according to a simple technical protocol. Dublin Core (unqualified) is the minimum interchange standard required by OAI; however, any other metadata set described by an XML schema (such as the CDWA Lite XML Schema) can be used for more detailed description. OAI is designed to be easy to implement, with low technical barriers. Available in English only.
CHIN Guide to Museum Standards (PDF, 544 KB)
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This resource was published by the Canadian Heritage Information Network (CHIN). For comments or questions regarding this content, please contact CHIN directly. To find other online resources for museum professionals, visit the CHIN homepage or the Museology and conservation topic page on Canada.ca.
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