Shapely functions as sample process

[jeafreezy]

Overview

This PR exposes some selected shapely functions as sample process. The selection cut across different operations in shapely. It uses the name of the category of that function as the namespace. E.g union operation under the set module is described as set:union. This is to avoid clashes with other functions.

As mentioned in the issue, it accepts list of geometry inputs (WKT and/or GeoJSON geometry), performs the operation and returns the result in the specified output_format (optional).

The approach is describe in the image below:

Related issue / discussion

https://github.com/geopython/pygeoapi/issues/1439

Additional information

Todo/Idea/Challenge

• Tests(units) - I didn't see any test for process in the codebase. I tried writing one, but I need to spend some more time to understand the test structure.

• I am yet to figure out how to pass optional function parameters in the inputs. I am still confused on the data type to use in the metadata, especially since different functions require different parameters. e.g buffer operation requires distance. @tomkralidis and I discussed an alternative approach earlier today, which is using different classes for different functions. That could potentially solve this issue. But I didn't have much time to explore that. Although this may also lead to repetitive code. Since the idea is to have it as a sample, hopefully this current implementation is sufficient.

• Idea: Perhaps in the future, it will be great to chain functions. E.g passing multiple operations like ['buffer', 'join'] can be interpreted as perfoming the buffer operation on the geometries, followed by the join operation before returning the result.

Dependency policy (RFC2)

• [x] I have ensured that this PR meets RFC2 requirements

Updates to public demo

• [ ] I have ensured that breaking changes to the pygeoapi master demo server have been addressed
  • [ ] https://github.com/geopython/demo.pygeoapi.io/blob/master/services/pygeoapi_master/local.config.yml

Contributions and licensing

(as per https://github.com/geopython/pygeoapi/blob/master/CONTRIBUTING.md#contributions-and-licensing)

• [x] I'd like to contribute [feature X|bugfix Y|docs|something else] to pygeoapi. I confirm that my contributions to pygeoapi will be compatible with the pygeoapi license guidelines at the time of contribution
• [x] I have already previously agreed to the pygeoapi Contributions and Licensing Guidelines

[francbartoli]

@jeafreezy thanks for your great contributions. I have just one general comment about security:

• Exposing these functions publicly would leave a big surface for DoS attacks so we should make sure that they are not enabled as default processes sample
• My suggestion is to pick up them from the configuration if additionally configured

[tomkralidis]

Agree; it makes sense to have the plugin in the codebase without having in default configuration.

[jeafreezy]

Thank you both for the review and feedback. Please, how do you think I should go about this? I have a few ideas;

• Should there be a new entry in the example-config.yml for functions, where the user can list the functions they want to enable? Something like below;

• Or the shapely-functions entry should be commented out in the config, so they user can enable it, if they want to ? Something like below;

• Or is there a better approach to implement the suggestion ?

Kindly advise. Thank you.

[webb-ben]

Hi @jeafreezy, I believe the correct approach would be to omit the configuration entirely from the default pygeoapi configuration file, and instead, documenting the capacities of the Shapely Process Provider here / location in source code

[jeafreezy]

Thank you @webb-ben . I will work on that

[jeafreezy]

Not sure if we need need pytest to ensure function of the process capacities.

Apart from that, small changes to docs and a couple of files I am not sure need to be included in this PR, got my +1.

Thank you for reviewing my PR. I will address the issues.

[jeafreezy]

Thank you for reviewing my PR @tomkralidis. I have addressed the issues to the best of my knowledge. Kindly let me know if there is anything else I missed. Thank you.

[tomkralidis]

Thank you @jeafreezy for this valuable contribution!