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Metadata Catalogue

The metadata catalogue is a central piece of the architecture, collecting and giving access to individual metadata records. In the geo-spatial domain, effective metadata catalogues are developed around the standards issued by the OGC, the Catalogue Service for the Web (CSW) and the OGC API Records.

Besides this essential compliance with international standards, metadata catalogues usually provide other important management functionalities: (i) metadata record editing, (ii) access control, (iii) records search, (iv) resource preview, (v) records harvesting, etc. More sophisticated metadata catalogues approach the functionalities of a Content Management System (CMS). The remainder of this section reviews two popular open-source geo-spatial metadata catalogues: GeoNetwork and pycsw.

GeoNetwork

This web-based software is centred on metadata management, providing rich edition forms. The editor supports the ISO19115/119/110 standards used for spatial resources and also Dublin Core. The user can upload data, graphics, documents, PDF files and any other content type to augment metadata records. Among others, GeoNetwork supports:

  • multilingual metadata record edition,
  • validation system,
  • automated suggestions for quality improvement,
  • publication of geo-spatial layers to software compliant with OGC services (e.g. GeoServer).

GeoNetwork implements the following protocols:

  • OGC CSW
  • OAI-PMH
  • OpenSearch
  • Z39.50

The metadata harvesting feature is quite broad, able to interact with the following resources:

  • OGC-CSW 2.0.2 ISO Profile
  • OAI-PMH
  • Z39.50 protocols
  • Thredds
  • Webdav
  • Web Accessible Folders
  • ESRI GeoPortal
  • Other GeoNetwork node

Besides the core metadata management functions, GeoNetwork also provides useful monitoring and reporting tools. It is able to easily synthesise the content of the catalogue with statistics and graphics. A system status is also available to the system administrator.

Use cases

The GeoNetwork project started out in 2001 as a Spatial Data Catalogue System for the Food and Agriculture organisation of the United Nations (FAO), the United Nations World Food Programme (WFP) and the United Nations Environmental Programme (UNEP). Other relevant projects and institutions using GeoNetwork include:

pycsw

pycsw is a catalogue component offering an HTML frontend and query interface using various standardised catalogue APIs to serve multiple communities. Pycsw, written in python, allows for the publishing and discovery of geospatial metadata via numerous APIs (CSW 2/CSW 3, OpenSearch, OAI-PMH, SRU), providing a standards-based metadata and catalogue component of spatial data infrastructures. pycsw is Open Source, released under an MIT license, and runs on all major platforms (Windows, Linux, Mac OS X).

  • Technology: python
  • License: MIT
  • OSGeo project

Functionality

Functionality of the pycsw is from the SoilWise perspective identical to GeoNetwork's functionality.

  • query metadata
  • M: filter by (configurable set of) properties (AND/OR/NOT, FullTextSearch, by geography)
  • M: Sorting and pagination
  • S: aggregate results (faceted search)
  • W: customise ranking of the results
  • OGC:CSW, OGCAPI:Records, OAI-PMH
  • Search engine discoverability / Schema.org
  • Link to data download / data preview

Use cases

pycsw is a core component of GeoNode and is the core of the CKAN spatial extension, used for example by FAO. pycsw is used in various projects:

In preparation:

  • Soils for Africa