The Document Availability Information API (DAIA) defines a data model with serializations in JSON, XML, and RDF to encode and query information about the current availability of documents. The specification is being refined since 2008. See http://purl.org/NET/DAIA for a detailed specification. An XML Schema can be found at http://purl.org/NET/DAIA/schema.xsd (also in HTML) and an RDF ontology at http://purl.org/ontology/daia. A reference implementation in Perl is available at CPAN to create your own DAIA servers, wrappers, and clients. It includes a simple DAIA validator and converter. A public validator is available at http://daia.gbv.de/validator/.
More and more services of libraries are also offered through APIs that fit into a service oriented architecture (SOA). Most of the fundamental actions are covered by (web) APIs. For Search there is SRU/SRW, Z39.50, and OpenSearch, for Harvest and Syndicate there is OAI-PMH, RSS, and Atom Syndication, for Upload and Edit there is SRU Update, and the Atom Publishing Protocol, for Copy and Provide there is unAPI, COinS, and Microformats, and for Identity Management there is Shibboleth and OpenID. At the same time library formats evolve from semi-structured digital catalog cards (MARC) to more structured formats such as MODS and RDA. Availability of documents and holdings in libraries, however, has lacked a clear and open specification. The Document Availability Information API (DAIA) fills this gap.
DAIA was first designed as a simple REST-API with a conceptual data model, independent from serialization formats, in mind. It started as expression of basic availability concepts in XML and JSON, which are specified at http://purl.org/NET/DAIA. A serialization in RDF is being developed now, to be incorporated in the final DAIA specification. The current DAIA ontology is located at http://purl.org/ontology/daia.
The DAIA data model can be viewed from a tree-oriented data view like XML and JSON or from a graph-oriented data view like RDF. The following two diagrams illustrate both views
Also available On one page (A4) for printing.
The basic question to be answered by the Document Availability Information API (DAIA) is:
Is a specific document available at a specific institution and how can I get it?
This implies that DAIA is not mainly about:
DAIA is not about loan - Traditional libraries only held physical objects that you were able to look at or even loan. In the digital world this is only one special case. As soon as you have digitized an object, the difference between viewing the digital document and copying the digital documents becomes senseless (copyright advocates may have a different view, but copyrith as the right to prevent circulation of information that has already been published is hopefully becoming a antiquated concept). Availability information also contains information about the possibility to loan an object, but its not the main point.
DAIA is not about discovery - Either you know which document you want - so you have an identifier, or you first have to find out which document you want - and its identifier. DAIA is not about this task. The same applies for the institution you ask for availability. Either you can refer to it with an identifier or you cannot. Please remember that in the digital world objects and concepts without a known identifier are as lost as a book that has been put to a wrong shelf in a large library magazine.
To understand DAIA you need to keep in mind some general design considerations:
In the end availability is a binary value about a service you want to do with a resource. In the library context the basic services can be defined as:
In addition there can be mutliple facets like delay time or specific limitations etc. but this is all optional.
In the context of ILS Discovery Interface Task Force and its official recommendation (revision 1.1, released in December 2008) DAIA fits to the GetAvailability method (section 6.3.1).
See notes at DAIA/Review.
This page is beeing worked on. Have a look at the German introduction Verfügbarkeitsrecherche mit DAIA and the DAIA Format specification. Please sent comments and questions to jakob dot voss at gbv.de.
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