TopIntroduction
Metadata is data about data (Dublin Core Metadata Initiative [DCMI], 2014). Metadata facilitates discovery of relevant information, helps in organizing electronic resources, facilitate interoperability and legacy, resource integration, provide digital identification and support archiving and preservation (National Information Standards Organization[NISO], 2004). Metadata is a summary document providing content, quality, type, creation, and spatial information about a data set. It can be stored in any format such as a text file, Extensible Markup Language (XML), or database record. Because of its small size compared to the data it describes, metadata is more easily shareable (Environmental Systems Research Institute, [ESRI], 2002). Recognition of the many uses of metadata has led to the construction of a very broad typology of metadata as being descriptive, administrative or structural (Caplan, 2003). Metadata Standards are sets of topic-specific norms that guide the collection and documentation of metadata resulting in consistent collection criteria, nomenclature, structure and enable interoperability (Hogrefe & Stocks, 2011).
Interoperability is the ability of multiple systems with different hardware and software platforms, data structures and interfaces to exchange data with minimal loss of content and functionality (NISO as cited by Zeng & Qin, 2008). Metadata interoperability is a qualitative property of metadata information objects that enables systems and applications to work with or use these objects across system boundaries (Haslhofer & Klas, 2010). Interoperable metadata allows multiple systems to work with the same set of data and metadata. It helps ensure metadata records associated with one resource can be accessed, accurately interpreted and subsequently used by a system or integrated with metadata records associated with other resources (Neiswender & Montgomery, 2009). In order to maintain interoperability across related metadata standards, it is necessary to create software systems able to process several metadata dialects or provide crosswalks between metadata standards. Crosswalks support the ability of search engines to search effectively across heterogeneous databases, i.e. they promote interoperability (Nogueras-Iso, Zarazaga-Soria, Lacasta, Bejar, & Muro-Medrano, 2004).Crosswalks (sometimes called “tag mapping” or metadata translation”) are used for “translating between metadata formats. Dublin Core Metadata Glossary views crosswalks as a table that maps the relationships and equivalences between two or more metadata formats. The technological universe of crosswalks, mapping, federated searching of heterogeneous databases and aggregating metadata sets into single repositories is rapidly changing. Crosswalks and metadata mappings are still at the heart of data conversion projects and semantic interoperability which enables searching across heterogeneous resources (Woodley, 2008).Crosswalks can apply to content standards, vocabularies, or both and crosswalking is generally done when datasets using different metadata standards or vocabularies need to be integrated (Wang, Isenor, & Graybeal, 2011).Metadata schemas are sets of metadata elements designed for a specific purpose, such as describing a particular type of information resource (NISO, 2004).It is a mapping of elements, semantics and syntax from one metadata scheme to another. The elements of one metadata set are correlated with the elements of another metadata set that have the same or similar meaning (Godby, Young, & Childress, 2004). The process is also sometimes called as “semantic mapping” since it essentially provides mapping of metadata elements from one standard to another (Shah & Arora, 2009).