Exercise 6 - Metadata via OGC API - Records

OGC API - Records provides a Web API with the capability to create, modify, and query metadata on the Web:

• OGC API - Records: Part 1: Core (draft)

OGC API - Records uses OGC API - Features as a building block, thus enabling streamlined deployment and integration for clients and users.

pygeoapi support

pygeoapi supports the OGC API - Records draft specification, using Elasticsearch and TinyDB rasterio as core backends.

Note

See the official documentation for more information on supported catalogue/metadata backends

Publish metadata records in pygeoapi

With pygeoapi we can setup OGC API - Records using any supported data provider. In this exercise we will use the TinyDB Catalogue backend. We will use the sample catalogue in workshop/exercises/data/records/catalogue.tinydb.

Update the pygeoapi configuration

Open the pygeoapi configuration file in a text editor. Add a new dataset section as follows:

    example_catalogue:
        type: collection
        title: FOSS4G Florence Record catalogue
        description: FOSS4G Florence Record catalogue (OGC API - Records)
        keywords:
            - Services
            - Infrastructures
            - Florence
            - FOSS4G
        links:
            - type: text/html
              rel: canonical
              title: information
              href: http://opendata.comune.firenze.it
              hreflang: en-US
        extents:
            spatial:
                bbox: [11.145, 43.718, 11.348, 43.84]
                crs: http://www.opengis.net/def/crs/OGC/1.3/CRS84
        providers:
            - type: record
              name: TinyDBCatalogue
              data: /data/records/catalogue.tinydb
              id_field: externalId
              time_field: recordCreated
              title_field: title

Save the configuration and restart Docker Compose. Navigate to http://localhost:5000/collections to evaluate whether the new dataset has been published.

Metadata formats

By default, pygeoapi supports and expects the OGC API - Records core record model and queryables. For additional metadata formats, you can develop your own custom pygeoapi plugin, or convert your metadata to OGC API - Records core record model before adding to pygeoapi.

Install OWSLib

If you do not have Python installed, consider running this exercise in a Docker container. See the Setup Chapter.

pip3 install owslib

Sample ISO 19139 to TinyDBCatalogue loader

It is possible to load more example ISO19139 metadata in a TinyDB database with the following script (raw)

cd workshop/exercises/data/records
curl -O https://raw.githubusercontent.com/geopython/pygeoapi/master/tests/load_tinydb_records.py
python3 load_tinydb_records.py xml catalogue.tinydb

Client access

QGIS

QGIS supports OGC API - Records via the MetaSearch plugin. MetaSearch originally focused on Catalogue Service for the Web (OGC:CSW) only, but has been extended to OGC API - Records. MetaSearch is a default plugin in QGIS and requires no further installation.

Query OGC API - Records from QGIS

Follow these steps to connect to a service and query datasets:

• Locate the MetaSearch plugin in the Web menu or on the Toolbar . The main search panel will appear with the default MetaSearch catalogue list already populated.

• open the Services tab, to find the New button to create a new connection
• add a connection to https://demo.pygeoapi.io/master
• click Service Info to get information about the service
• return to the Search tab
• select the connection you have just created
• type a search term and click search
• notice that when you select a search result, a red footprint is drawn on the map highlighting the location of the dataset

OWSLib is a Python library to interact with OGC Web Services and supports a number of OGC APIs including OGC API - Records.

Interact with OGC API - Records via OWSLib

If you do not have Python installed, consider running this exercise in a Docker container. See the Setup Chapter.

pip3 install owslib

Then start a Python console session with: python (stop the session by typing exit()).

>>> from owslib.ogcapi.records import Records
>>> SERVICE_URL = 'https://demo.pygeoapi.io/master/'
>>> w = Records(SERVICE_URL)
>>> w.url
'https://demo.pygeoapi.io/master'
>>> dutch_metacat = w.collection('dutch-metadata')
>>> dutch_metacat['id']
'dutch-metadata'
>>> dutch_metacat['title']
'Sample metadata records from Dutch Nationaal georegister'
>>> dutch_metacat['description']
'Sample metadata records from Dutch Nationaal georegister'
>>> dutch_metacat_query = w.collection_items('dutch-metadata', limit=1)
>>> dutch_metacat_query['numberMatched']
198
>>> dutch_metacat_query['numberReturned']
1
>>> dutch_metacat_query = w.collection_items('dutch-metadata', q='Wegpanorama')
>>> dutch_metacat_query['numberMatched']
2

Note

See the official OWSLib documentation for more examples.

Summary

Congratulations! You are now able to publish metadata to pygeoapi.