Transition to Apache License 2.0: License Update, Author Attribution, and Documentation Compliance

[vschaffn]

Description

This PR implements the transition of the xDEM project license from MIT to Apache License 2.0.
Resolves #555

Changes implemented

• The LICENSE file has been updated with the full text of the Apache v2.0 license.
• A NOTICE file has been added to comply with Apache licensing requirements. The file includes necessary copyright notices and details about dependencies used by xdem, including Python, NumPy, Matplotlib, SciPy, Geoutils, Rasterio, GeoPandas, Numba, pyproj, tqdm, scikit-image, scikit-gstat, pyogrio, pandas, scikit-learn, OpenCV, affine, Shapely, pytransform3d, yaml and noisyopt.
• An AUTHORS.md file has been created listing the main contributors of the project along with their contact information, while mentioning their affiliation with the xDEM developers' copyright.
• All source code files have been updated with the new Apache v2.0 license header, which is the following:

# Copyright (c) 2024 xDEM developers.
#
# This file is part of the xdem project:
#   https://github.com/glaciohack/xdem
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at:
#   http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

• The setup.cfg has been updated with the new license and copyright as well as conf.py

Notes

• There are certainly other contributors to add to the project, so don't hesitate to let me know.
• The packages listed in NOTICE and in setup.cfg are not aligned anymore. This will be solved by [POC] Makefile installations #582.
• PR to be merged after Remove RichDEM from source, moved utility functions to conftest.py #612.
• The copyrights and authors cited in the documentation must be checked for consistency with the project Decide on author attribution across GeoUtils and xDEM #431.

[adebardo]

In demcompare, the setup files have a header; I'm checking to see if it's necessary here or not.

[duboise-cnes]

not needed, doesn't need to be overcopyrighted ;) setup follows usually a standard way and no invention to be copyrighted.

[adebardo]

I'm checking on the dates because I don't think 2024 is the correct one.

[duboise-cnes]

but you can adapt to last current year and 2024 can be fit. Depends on the politic on that. On projects, I usually update it to the current year when modified. You modify it, you put the current year. Ok for me... even if it not that problematic.

[adebardo]

I'm looking into setting up a changelog file.

[rhugonnet]

Really great to have this done rigorously! 🙂
On the next step you list for adding more contributors: I would start obviously by adding yourselves @vschaffn @adebardo 😉. Then, should we consider listing those that do not have commits but contributed to important amount of code through other packages that have been or are being adapted in xDEM? (@duboise-cnes, but also for instance @iamdonovan & potentially others; if they feel it is warranted).

Other than that, I have three remarks:

1. Should we also modify the "author" name of PyPI with the same "xdem contributors" name?

   xdem/setup.cfg

   Line 2 in 3287594

   author = The GlacioHack Team

2. Should we also update the documentation copyright here:

   xdem/doc/source/conf.py

   Line 28 in 3287594

   copyright = "2021, Erik Mannerfelt, Romain Hugonnet, Amaury Dehecq and others"

   
   I think I remember @sdinot mentioning the copyright for the documentation being separate? What would be the best practice here? (it seems easier to have a single one)
3. Should we also update the Zenodo repository of the package accordingly? https://zenodo.org/records/4809698.

Final note: if we address these points consistently, this PR would also resolve #431!

[sdinot]

2. I think I remember @sdinot mentioning the copyright for the documentation being separate? What would be the best practice here? (it seems easier to have a single one)

To be precise, I wasn't talking about the copyright notice, but about the license, which must be adapted to the nature of the protected work. The Apache v2.0 license is a permissive open source license adapted to software. Its vocabulary and clauses make it less suitable for documentation. For the latter, a permissive open source license dedicated to literary and artistic works, such as the Creative Commons Attribution 4.0 International (CC BY 4.0) license, would be more appropriate.

Those of you who read French (or have a good automatic translator) can read the blog post I wrote on this subject:
Projet libre : à chaque ressource sa licence.

[rhugonnet]

Thanks @sdinot, your blog post is a great resource! (I'll also peak at the /e/OS/ post for my Fairphone later 😄)
Adding a CC BY 4.0 for the documentation sounds perfect, and potentially a 0BSD for code snippets/examples.

You give an example of what the package's README would look like. Would it also be good to add a short version of this notice at the bottom of the documentation pages? If yes, what would this look like (something like: "Copyright xDEM developers: text and figures CC BY 4.0, code snippets 0BSD")?

[duboise-cnes]

Really great to have this done rigorously! 🙂 On the next step you list for adding more contributors: I would start obviously by adding yourselves @vschaffn @adebardo 😉. Then, should we consider listing those that do not have commits but contributed to important amount of code through other packages that have been or are being adapted in xDEM? (@duboise-cnes, but also for instance @iamdonovan & potentially others; if they feel it is warranted).

Other than that, I have three remarks:

1. Should we also modify the "author" name of PyPI with the same "xdem contributors" name? https://github.com/GlacioHack/xdem/blob/3287594522d91542a6b747a77c931597f4db28ad/setup.cfg#L2

2. Should we also update the documentation copyright here: https://github.com/GlacioHack/xdem/blob/3287594522d91542a6b747a77c931597f4db28ad/doc/source/conf.py#L28
   
   I think I remember @sdinot mentioning the copyright for the documentation being separate? What would be the best practice here? (it seems easier to have a single one)

3. Should we also update the Zenodo repository of the package accordingly? https://zenodo.org/records/4809698.

Final note: if we address these points consistently, this PR would also resolve #431!

I am ok to be added in contributors list (with emmanuel.dubois@cnes.fr) even no commits yet (I will try at some point when less crowded in CNES) : that allows to identify CNES in contributions simply.
Don't forget to add CNES copyright on "real" further contributions on future code from demcompare (CLI, ....). Not needed on this PR, which is only a copyright clean, an important but not complex contribution. So ok for this one, but to be careful on following ones to choose wisely where to go on copyright. If it is not clear, ask me PR after PR on CNES funded ones.

Pypi author and documentation should be also changed, i agree.
For the documentation, see sebastien answer but not needed on each file but globally with any adapted documentation licence. Great if it is clean but doesn't have the best choice, simply an understable and classical ones for readers and doc contributors.

Hope it helps to finish this PR

[vschaffn]

Many thanks for your feedback !
@adebardo Every packages used in source are now listed in NOTICE. Then I will modify setup.cfg but this would be for #582.
@rhugonnet I have changed xdem to xDEM wherever applicable, and added the contributors you mentionned.
@duboise-cnes I have noted your comment about the CNES copyright, and I will keep that in mind for future contributions.

[rhugonnet]

@erikmannerfelt Do you want an email to be added for you here?

[rhugonnet]

@erikmannerfelt Reminder on this

[rhugonnet]

All good for me, just the couple comments above!
We can add the contributors I asked later (in a separate PR), so no problem to merge this directly next week 🙂.

[rhugonnet]

Given this statement, do we need to have a "Contributor License Agreement" section in CONTRIBUTING.md, or is this just a generic terminology?
(We can also add "the" before "Contributor License Agreement"!)

[duboise-cnes]

Good review @rhugonnet : We can indeed remove this statement. We have chosen not to go to a contributor license agreement model. If needed at some point, this will be further evolution.

[sdinot]

You give an example of what the package's README would look like. Would it also be good to add a short version of this notice at the bottom of the documentation pages? If yes, what would this look like (something like: "Copyright xDEM developers: text and figures CC BY 4.0, code snippets 0BSD")?

We could indeed consider placing a copyright notice on all pages of the documentation, as we do in the source code. But the practice is different for documentation. In general, authors simply indicate the license of the code, documentation and other project resources on a dedicated page of the documentation.

This difference in practice between source code and documentation is probably due to the fact that a source code file can more easily be extracted from its context and reused in another than a page of documentation. We therefore ensure that each source code file is legally “self-supporting”. It contains not only the source code, but also the name of the copyright holder, the license and the origin of the file.

[rhugonnet]

@vschaffn I re-tagged @erikmannerfelt and @fmaussion regarding the author listing + email.
If they don't answer in the next days, feel free to merge the PR anyways, we can adjust those things later on 😉.