FAQ

Can I use pycsw within my WSGI application?

How do I export my repository?

How do I add a custom metadata format?

How can I catalogue ‘sets’ of metadata?

How can I handle transactions safely?

How can I make CSW POST XML requests?

Does pycsw have a GUI/webapp/interface?

I have 2147 metadata records. How do I add them?

How do I add metadata from a WAF?

How do I harvest huge OGC services without getting HTTP timeout errors?

Is pycsw customizable or extensible?

Why am I getting a ‘Connection refused’ error when connecting pycsw?

When doing a GetRecords why are there no results?

My pycsw install doesn’t work at all with QGIS

Can I use pycsw within my WSGI application?

Yes. pycsw can be deployed as both via traditional CGI or WSGI. You can also integrate pycsw via Django views, Pylons controllers or Flask routes.

How do I export my repository?

Use the pycsw-admin.py utility to dump the records as XML documents to a directory:

pycsw-admin.py export-records -f default.cfg -p /path/to/output_dir

How do I add a custom metadata format?

pycsw provides a plugin framework in which you can implement a custom profile (see Profile Plugins)

How can I catalogue ‘sets’ of metadata?

Create a ‘parent’ metadata record from which all relevant metadata records (imagery, features) derive from via the same dc:source element of Dublin Core or apiso:parentIdentifier element of ISO 19139:2007. Then, do a GetRecords request, filtering on the identifier of the parent metadata record. Sample request:

<?xml version="1.0" encoding="ISO-8859-1" standalone="no"?>
<csw:GetRecords xmlns:csw="http://www.opengis.net/cat/csw/2.0.2" xmlns:ogc="http://www.opengis.net/ogc" service="CSW" version="2.0.2" resultType="results" startPosition="1" maxRecords="5" outputFormat="application/xml" outputSchema="http://www.opengis.net/cat/csw/2.0.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.opengis.net/cat/csw/2.0.2 http://schemas.opengis.net/csw/2.0.2/CSW-discovery.xsd" xmlns:gml="http://www.opengis.net/gml" xmlns:gmd="http://www.isotc211.org/2005/gmd" xmlns:apiso="http://www.opengis.net/cat/csw/apiso/1.0">
  <csw:Query typeNames="csw:Record">
    <csw:ElementSetName>brief</csw:ElementSetName>
    <csw:Constraint version="1.1.0">
      <ogc:Filter>
        <ogc:And>
          <ogc:PropertyIsEqualTo>
            <ogc:PropertyName>apiso:parentIdentifier</ogc:PropertyName>
            <ogc:Literal>$identifier</ogc:Literal>
          </ogc:PropertyIsEqualTo>
          <ogc:BBOX>
            <ogc:PropertyName>ows:BoundingBox</ogc:PropertyName>
            <gml:Envelope>
              <gml:lowerCorner>47 -5</gml:lowerCorner>
              <gml:upperCorner>55 20</gml:upperCorner>
            </gml:Envelope>
          </ogc:BBOX>
        </ogc:And>
      </ogc:Filter>
    </csw:Constraint>
  </csw:Query>
</csw:GetRecords>

The above query will search for all metadata records of the same apiso:parentIdentifier (identified by $identifier) within a given area of interest. The equivalent query can be done against dc:source with the same design pattern.

How can I handle transactions safely?

Transactions are handled by an IP-based authentication list which can be set in pycsw’s configuration (in manager.allowed_ips). Supported notations includes traditional IP address, wildcard, and CIDR.

How can I make CSW POST XML requests?

HTTP POST requests with XML are a bit different than the traditional HTTP POST approach (key=value). An HTTP client opens a connection to the server and sends XML directly. CSW implements HTTP POST in this manner with XML requests.

There are numerous ways to make this type of request, but here are a few:

Python

import requests
requests.post('http://demo.pycsw.org/cite/csw', data=open('/path/to/request.xml').read()).text

from owslib.util import http_post
# see owslib.util.http_post in https://github.com/geopython/OWSLib/blob/master/owslib/util.py
response = http_post('http://demo.pycsw.org/cite/csw', request=open('/path/to/request.xml').read())

Command line tools:

# pycsw-admin.py utility
pycsw-admin.py post-xml -u http://demo.pycsw.org/cite/csw -x /path/to/request.xml

# curl
curl -X POST -d @/path/to/request.xml http://demo.pycsw.org/cite/csw

# lwp-request
cat /path/to/request.xml | POST http://demo.pycsw.org/cite/csw

# wget
wget http://demo.pycsw.org/cite/csw --post-file=/path/to/request.xml

Does pycsw have a GUI/webapp/interface?

No. pycsw is a headless metadata catalog. Administration is via command line. For full metadata management, applications like CKAN, GeoNode and Open Data Catalog are built with pycsw inside and provide functionality to manage metadata via a GUI.

I have 2147 metadata records. How do I add them?

Add metadata using pycsw-admin.py:

# read a directory of metadata files
pycsw-admin.py load-records -f /path/to/default.cfg -p /path/to/records

# read a directory of metadata files, recursively
pycsw-admin.py load-records -f /path/to/default.cfg -p /path/to/records -r

See Loading Records in the documentation.

How do I add metadata from a WAF?

Use the pycsw-admin.py utility and CSW’s Harvest operation against your own server:

pycsw-admin.py post-xml -u http://localhost/csw -x /path/to/harvest-waf.xml

harvest-waf.xml:

<?xml version="1.0" encoding="UTF-8"?>
<Harvest xmlns="http://www.opengis.net/cat/csw/2.0.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.opengis.net/cat/csw/2.0.2 http://schemas.opengis.net/csw/2.0.2/CSW-publication.xsd" service="CSW" version="2.0.2">
  <Source>http://demo.pycsw.org/waf</Source>
  <ResourceType>urn:geoss:waf</ResourceType>
</Harvest>

How do I harvest huge OGC services without getting HTTP timeouts?

The CSW Harvest operation supports asynchronous processing via the ResponseHandler parameter. When specified, this parameter allows the request to continue while returning the response to the client. The client will then be notified of completion via URI value of the ResponseHandler parameter being sent.

pycsw supports both FTP and SMTP-based ResponseHandler processing:

FTP (result gets pushed to ftp://host/result.xml):

<?xml version="1.0" encoding="UTF-8"?>
<Harvest xmlns="http://www.opengis.net/cat/csw/2.0.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.opengis.net/cat/csw/2.0.2 http://schemas.opengis.net/csw/2.0.2/CSW-publication.xsd" service="CSW" version="2.0.2">
  <Source>http://demo.pycsw.org/waf</Source>
  <ResourceType>urn:geoss:waf</ResourceType>
  <ResponseHandler>ftp://host/result.xml</ResponseHandler>
</Harvest>

SMTP (result gets emailed to you@example.com. See the docs for more information on configuring server.smtp_host):

<?xml version="1.0" encoding="UTF-8"?>
<Harvest xmlns="http://www.opengis.net/cat/csw/2.0.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.opengis.net/cat/csw/2.0.2 http://schemas.opengis.net/csw/2.0.2/CSW-publication.xsd" service="CSW" version="2.0.2">
  <Source>http://demo.pycsw.org/waf</Source>
  <ResourceType>urn:geoss:waf</ResourceType>
  <ResponseHandler>mailto:you@example.com</ResponseHandler>
</Harvest>

Is pycsw customizable or extensible?

Yes. See our API docs for examples on deploying pycsw in a custom application/framework.

Why am I getting a ‘Connection refused’ error when connecting to pycsw?

Most CSW client tools (e.g. QGIS MetaSearch, OWSLib, etc.) derive the CSW URL from the GetCapabilities reponse XML, as opposed to using directly the URL you provide. Ensure that the server.url configuration value is set to ensure the URL to be advertised in the CSW Capabilities XML.

When doing a GetRecords why are there no results?

The default result type of a GetRecords response is a hit count, which does not show any records per se but provides a summary of the search result

<csw:SearchResults nextRecord="101"
                   numberOfRecordsMatched="1972"
                   numberOfRecordsReturned="100"
                   recordSchema="http://www.opengis.net/cat/csw/2.0.2"
                   elementSet="full"/>

To return actual records add resulttype=results to the GetRecords request.

My pycsw install doesn’t work at all with QGIS

A key component of the pycsw configuration is the server.url directive. When working with CSW servers, applications such as QGIS MetaSearch and OWSLib read a CSW’s Capabilities XML document to be able to ‘bind’ to the appropriate URL when making subsequent CSW requests.

For example, in the pycsw case, if your server.url directive is set to http://localhost:8000, but your server is deployed to http://example.org/pycsw, QGIS MetaSearch, OWSLib and other CSW clients will intially connect to http://example.org/pycsw to derive the Capabilities XML response, and then use http://localhost:8000 for subsequent requests (such as GetRecords, GetDomain, GetRecordById, etc.).

The end result is having a pycsw instance that is able to respond to a GetCapabilities request but nothing more, in tools like QGIS/MetaSearch, OWSLib, etc.

This is a feature, not a bug. What’s going on here?

Standards-wise, this is all valid and proper. OGC CSW uses OWS Common to be able to identify, well, common constructs of service metadata in the CSW 2/3 Capabilities XML response. OWS Common’s OperationsMetadata section defines various binding endpoints/URLs for each OWS operation. This means you can, in theory, have a given URL for GetCapabilities requests, and a different URL for GetRecords requests. In the pycsw case, the server.url directive is used across the server’s Capabilities XML for simplicity. It is critical to ensure this URL is consistent with your deployment as advertised and published.

A common area which this may cause errors is in the case of pycsw servers deployed with HTTPS but server.url directives set to http://.... Currently (2020), numerous services are or have migrated from HTTP to HTTPS, and include web server redirects to manage traffic accordingly. Given CSW servers include support for XML POST, a web server’s redirect may not pass along the XML payload as part of the redirect.

Here’s a bare bones example of the differences between HTTP and HTTPS responses using curl with the same request (this mimics essentially QGIS MetaSearch/OWSLib behaviour):

# request example 1: works
curl -s https://raw.githubusercontent.com/geopython/pycsw/master/tests/functionaltests/suites/default/post/GetRecords-all.xml
| curl -X POST -d @- https://example.org/pycsw

# request example 2: does not work
curl -s https://raw.githubusercontent.com/geopython/pycsw/master/tests/functionaltests/suites/default/post/GetRecords-all.xml
| curl -X POST -d @- http://example.org/pycsw

Here’s what happens in request example 2:

It is this behaviour that results in, for example, QGIS MetaSearch and OWSLib errors.

Setting server.url accordingly will alleviate these issues and will allow pycsw to continue to work as expected with CSW clients.

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