Update WFS3 via OWSLib

[borrob]

With PR #312 the OWSLib is updated to version 0.19 which seem to open possibilities to improve on the WFS probe. See TODO in the code base like here and here.

Can we also enable the WFS3Caps probe and WFS3Collection probe ? Shall we rename them to OGC API or OGC Feature API ?

[tomkralidis]

Note updates geopython/OWSLib#653

+1 to rename probes. Perhaps OGCAPIFeaturesLandingPage and OGCAPIFeaturesCollection ? Future probes can carry on with OGCAPI... pattern. Thoughts?

[justb4]

+1 to rename Probes, but in separate issue, as is quite involved:

1. Rename Probe enum type OGC:WFS3 to I propose OGC:OAPIF.

2. Probe class renaming will also require (Alembic) database upgrades for existing deployments:

• table: resource column resource_type rename typename
• table: probe_vars column probe_class rename class-names

On demo.geohealthcheck.org database upgrades are automatically applied on auto-redeploy.

[tomkralidis]

+1. For enum types, we can change sooner than later or wait until opengeospatial/ogcapi-common#35 is addressed by OGC.

[borrob]

+1 for enums, but indeed in a separate issue. To avoid having to change it again, I would suggest waiting until OGC made it official

[justb4]

Ok, renaming within the DB is easy via Alembic, the upgrades can use SQLAlchemy like:

    resources = Resource.query.all()
    for resource in resources:
        if resource.resource_type == 'OGC:WFS3':
            resource.resource_type = 'OGC:OAFeat'
            print('Changed resource type for: %s' % resource.url)
            break
    DB.session.commit()

Similar for probe_vars table.

[justb4]

Interesting question: how to enforce JSON-only responses from an OAFeat endpoint compliant with standard: f=json or content negotiation (Accept: header in HTTP request). See also: https://gitter.im/opengeospatial/WFS_FES?at=5f9962bfc10273610acf016d

and the answer is:

You have to use the Accept header, this is the only requirement in the standard, consistent with the HTTP standard.
http://docs.opengeospatial.org/is/17-069r3/17-069r3.html#encodings

[justb4]

Most thus solved in #338. Closing, remaining TODO spread over two issues: #339 and #340.