diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000000000000000000000000000000000000..68708728197a5774d0b68cdd676cd092103aa1fe
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,15 @@
+*~
+build
+/.coverage
+/.coverage.*
+dist
+*.egg-info/
+.eggs/
+.hypothesis
+*.pyc
+__pycache__
+.pytest_cache
+*.sw?
+.tox
+version.txt
+.mypy_cache/
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
new file mode 100644
index 0000000000000000000000000000000000000000..69b33490b621ead79cc10580132da2804d49f842
--- /dev/null
+++ b/.pre-commit-config.yaml
@@ -0,0 +1,40 @@
+repos:
+- repo: https://github.com/pre-commit/pre-commit-hooks
+ rev: v2.4.0
+ hooks:
+ - id: trailing-whitespace
+ - id: flake8
+ - id: check-json
+ - id: check-yaml
+
+- repo: https://github.com/codespell-project/codespell
+ rev: v1.16.0
+ hooks:
+ - id: codespell
+
+- repo: local
+ hooks:
+ - id: mypy
+ name: mypy
+ entry: mypy
+ args: [swh]
+ pass_filenames: false
+ language: system
+ types: [python]
+
+- repo: https://github.com/python/black
+ rev: 19.10b0
+ hooks:
+ - id: black
+
+# unfortunately, we are far from being able to enable this...
+# - repo: https://github.com/PyCQA/pydocstyle.git
+# rev: 4.0.0
+# hooks:
+# - id: pydocstyle
+# name: pydocstyle
+# description: pydocstyle is a static analysis tool for checking compliance with Python docstring conventions.
+# entry: pydocstyle --convention=google
+# language: python
+# types: [python]
+
diff --git a/AUTHORS b/AUTHORS
new file mode 100644
index 0000000000000000000000000000000000000000..2d0a34af6f52cf3cf6b0c2f7bd0648fbd255e77f
--- /dev/null
+++ b/AUTHORS
@@ -0,0 +1,3 @@
+Copyright (C) 2015 The Software Heritage developers
+
+See http://www.softwareheritage.org/ for more information.
diff --git a/CODE_OF_CONDUCT.md b/CODE_OF_CONDUCT.md
new file mode 100644
index 0000000000000000000000000000000000000000..0ad22b51e38e1a3dc2792766db295fca2892142f
--- /dev/null
+++ b/CODE_OF_CONDUCT.md
@@ -0,0 +1,78 @@
+# Software Heritage Code of Conduct
+
+## Our Pledge
+
+In the interest of fostering an open and welcoming environment, we as Software
+Heritage contributors and maintainers pledge to making participation in our
+project and our community a harassment-free experience for everyone, regardless
+of age, body size, disability, ethnicity, sex characteristics, gender identity
+and expression, level of experience, education, socio-economic status,
+nationality, personal appearance, race, religion, or sexual identity and
+orientation.
+
+## Our Standards
+
+Examples of behavior that contributes to creating a positive environment
+include:
+
+* Using welcoming and inclusive language
+* Being respectful of differing viewpoints and experiences
+* Gracefully accepting constructive criticism
+* Focusing on what is best for the community
+* Showing empathy towards other community members
+
+Examples of unacceptable behavior by participants include:
+
+* The use of sexualized language or imagery and unwelcome sexual attention or
+ advances
+* Trolling, insulting/derogatory comments, and personal or political attacks
+* Public or private harassment
+* Publishing others' private information, such as a physical or electronic
+ address, without explicit permission
+* Other conduct which could reasonably be considered inappropriate in a
+ professional setting
+
+## Our Responsibilities
+
+Project maintainers are responsible for clarifying the standards of acceptable
+behavior and are expected to take appropriate and fair corrective action in
+response to any instances of unacceptable behavior.
+
+Project maintainers have the right and responsibility to remove, edit, or
+reject comments, commits, code, wiki edits, issues, and other contributions
+that are not aligned to this Code of Conduct, or to ban temporarily or
+permanently any contributor for other behaviors that they deem inappropriate,
+threatening, offensive, or harmful.
+
+## Scope
+
+This Code of Conduct applies within all project spaces, and it also applies when
+an individual is representing the project or its community in public spaces.
+Examples of representing a project or community include using an official
+project e-mail address, posting via an official social media account, or acting
+as an appointed representative at an online or offline event. Representation of
+a project may be further defined and clarified by project maintainers.
+
+## Enforcement
+
+Instances of abusive, harassing, or otherwise unacceptable behavior may be
+reported by contacting the project team at `conduct@softwareheritage.org`. All
+complaints will be reviewed and investigated and will result in a response that
+is deemed necessary and appropriate to the circumstances. The project team is
+obligated to maintain confidentiality with regard to the reporter of an
+incident. Further details of specific enforcement policies may be posted
+separately.
+
+Project maintainers who do not follow or enforce the Code of Conduct in good
+faith may face temporary or permanent repercussions as determined by other
+members of the project's leadership.
+
+## Attribution
+
+This Code of Conduct is adapted from the [Contributor Covenant][homepage], version 1.4,
+available at https://www.contributor-covenant.org/version/1/4/code-of-conduct.html
+
+[homepage]: https://www.contributor-covenant.org
+
+For answers to common questions about this code of conduct, see
+https://www.contributor-covenant.org/faq
diff --git a/CONTRIBUTORS b/CONTRIBUTORS
new file mode 100644
index 0000000000000000000000000000000000000000..168824fec62634e027fb71c378657b25e84ffeaf
--- /dev/null
+++ b/CONTRIBUTORS
@@ -0,0 +1,2 @@
+Daniele Serafini
+Ishan Bhanuka
diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000000000000000000000000000000000000..94a9ed024d3859793618152ea559a168bbcbb5e2
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,674 @@
+ GNU GENERAL PUBLIC LICENSE
+ Version 3, 29 June 2007
+
+ Copyright (C) 2007 Free Software Foundation, Inc. <http://fsf.org/>
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+ Preamble
+
+ The GNU General Public License is a free, copyleft license for
+software and other kinds of works.
+
+ The licenses for most software and other practical works are designed
+to take away your freedom to share and change the works. By contrast,
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+share and change all versions of a program--to make sure it remains free
+software for all its users. We, the Free Software Foundation, use the
+GNU General Public License for most of our software; it applies also to
+any other work released this way by its authors. You can apply it to
+your programs, too.
+
+ When we speak of free software, we are referring to freedom, not
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+ Developers that use the GNU GPL protect your rights with two steps:
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+ TERMS AND CONDITIONS
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+ "This License" refers to version 3 of the GNU General Public License.
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+ The "source code" for a work means the preferred form of the work
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+propagate the contents of its contributor version.
+
+ In the following three paragraphs, a "patent license" is any express
+agreement or commitment, however denominated, not to enforce a patent
+(such as an express permission to practice a patent or covenant not to
+sue for patent infringement). To "grant" such a patent license to a
+party means to make such an agreement or commitment not to enforce a
+patent against the party.
+
+ If you convey a covered work, knowingly relying on a patent license,
+and the Corresponding Source of the work is not available for anyone
+to copy, free of charge and under the terms of this License, through a
+publicly available network server or other readily accessible means,
+then you must either (1) cause the Corresponding Source to be so
+available, or (2) arrange to deprive yourself of the benefit of the
+patent license for this particular work, or (3) arrange, in a manner
+consistent with the requirements of this License, to extend the patent
+license to downstream recipients. "Knowingly relying" means you have
+actual knowledge that, but for the patent license, your conveying the
+covered work in a country, or your recipient's use of the covered work
+in a country, would infringe one or more identifiable patents in that
+country that you have reason to believe are valid.
+
+ If, pursuant to or in connection with a single transaction or
+arrangement, you convey, or propagate by procuring conveyance of, a
+covered work, and grant a patent license to some of the parties
+receiving the covered work authorizing them to use, propagate, modify
+or convey a specific copy of the covered work, then the patent license
+you grant is automatically extended to all recipients of the covered
+work and works based on it.
+
+ A patent license is "discriminatory" if it does not include within
+the scope of its coverage, prohibits the exercise of, or is
+conditioned on the non-exercise of one or more of the rights that are
+specifically granted under this License. You may not convey a covered
+work if you are a party to an arrangement with a third party that is
+in the business of distributing software, under which you make payment
+to the third party based on the extent of your activity of conveying
+the work, and under which the third party grants, to any of the
+parties who would receive the covered work from you, a discriminatory
+patent license (a) in connection with copies of the covered work
+conveyed by you (or copies made from those copies), or (b) primarily
+for and in connection with specific products or compilations that
+contain the covered work, unless you entered into that arrangement,
+or that patent license was granted, prior to 28 March 2007.
+
+ Nothing in this License shall be construed as excluding or limiting
+any implied license or other defenses to infringement that may
+otherwise be available to you under applicable patent law.
+
+ 12. No Surrender of Others' Freedom.
+
+ If conditions are imposed on you (whether by court order, agreement or
+otherwise) that contradict the conditions of this License, they do not
+excuse you from the conditions of this License. If you cannot convey a
+covered work so as to satisfy simultaneously your obligations under this
+License and any other pertinent obligations, then as a consequence you may
+not convey it at all. For example, if you agree to terms that obligate you
+to collect a royalty for further conveying from those to whom you convey
+the Program, the only way you could satisfy both those terms and this
+License would be to refrain entirely from conveying the Program.
+
+ 13. Use with the GNU Affero General Public License.
+
+ Notwithstanding any other provision of this License, you have
+permission to link or combine any covered work with a work licensed
+under version 3 of the GNU Affero General Public License into a single
+combined work, and to convey the resulting work. The terms of this
+License will continue to apply to the part which is the covered work,
+but the special requirements of the GNU Affero General Public License,
+section 13, concerning interaction through a network will apply to the
+combination as such.
+
+ 14. Revised Versions of this License.
+
+ The Free Software Foundation may publish revised and/or new versions of
+the GNU General Public License from time to time. Such new versions will
+be similar in spirit to the present version, but may differ in detail to
+address new problems or concerns.
+
+ Each version is given a distinguishing version number. If the
+Program specifies that a certain numbered version of the GNU General
+Public License "or any later version" applies to it, you have the
+option of following the terms and conditions either of that numbered
+version or of any later version published by the Free Software
+Foundation. If the Program does not specify a version number of the
+GNU General Public License, you may choose any version ever published
+by the Free Software Foundation.
+
+ If the Program specifies that a proxy can decide which future
+versions of the GNU General Public License can be used, that proxy's
+public statement of acceptance of a version permanently authorizes you
+to choose that version for the Program.
+
+ Later license versions may give you additional or different
+permissions. However, no additional obligations are imposed on any
+author or copyright holder as a result of your choosing to follow a
+later version.
+
+ 15. Disclaimer of Warranty.
+
+ THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
+APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
+HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY
+OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
+THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
+IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
+ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
+
+ 16. Limitation of Liability.
+
+ IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+ 17. Interpretation of Sections 15 and 16.
+
+ If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+ END OF TERMS AND CONDITIONS
+
+ How to Apply These Terms to Your New Programs
+
+ If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+ To do so, attach the following notices to the program. It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+ <one line to give the program's name and a brief idea of what it does.>
+ Copyright (C) <year> <name of author>
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+ If the program does terminal interaction, make it output a short
+notice like this when it starts in an interactive mode:
+
+ <program> Copyright (C) <year> <name of author>
+ This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+ This is free software, and you are welcome to redistribute it
+ under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License. Of course, your program's commands
+might be different; for a GUI interface, you would use an "about box".
+
+ You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU GPL, see
+<http://www.gnu.org/licenses/>.
+
+ The GNU General Public License does not permit incorporating your program
+into proprietary programs. If your program is a subroutine library, you
+may consider it more useful to permit linking proprietary applications with
+the library. If this is what you want to do, use the GNU Lesser General
+Public License instead of this License. But first, please read
+<http://www.gnu.org/philosophy/why-not-lgpl.html>.
diff --git a/Makefile.local b/Makefile.local
new file mode 100644
index 0000000000000000000000000000000000000000..249d0efee7b69d948e153e3abefaedae6fb290de
--- /dev/null
+++ b/Makefile.local
@@ -0,0 +1,2 @@
+FLAG=-v
+NOSEFLAGS=-v -s
diff --git a/PKG-INFO b/PKG-INFO
index e64ece76688e735e99bfc5f05278259220baf817..1caa4b57998c525be0d28b1da197960e4df8c9ff 100644
--- a/PKG-INFO
+++ b/PKG-INFO
@@ -1,6 +1,6 @@
Metadata-Version: 2.1
Name: swh.model
-Version: 0.6.1
+Version: 0.6.4
Summary: Software Heritage data model
Home-page: https://forge.softwareheritage.org/diffusion/DMOD/
Author: Software Heritage developers
diff --git a/bin/git-revhash b/bin/git-revhash
new file mode 100755
index 0000000000000000000000000000000000000000..69d1d1cdb63d6d7dcfe07ef1b0176faebe251e3a
--- /dev/null
+++ b/bin/git-revhash
@@ -0,0 +1,7 @@
+#!/usr/bin/env bash
+
+# Use
+# git-revhash 'tree 4b825dc642cb6eb9a060e54bf8d69288fbee4904\nparent 22c0fa5195a53f2e733ec75a9b6e9d1624a8b771\nauthor seanius <seanius@3187e211-bb14-4c82-9596-0b59d67cd7f4> 1138341044 +0000\ncommitter seanius <seanius@3187e211-bb14-4c82-9596-0b59d67cd7f4> 1138341044 +0000\n\nmaking dir structure...\n' # noqa
+# output: 17a631d474f49bbebfdf3d885dcde470d7faafd7
+
+echo -ne $* | git hash-object --stdin -t commit
diff --git a/bin/swh-hashtree b/bin/swh-hashtree
new file mode 100755
index 0000000000000000000000000000000000000000..5b85b7b5e73d24afc9d4e53b0a275327c2586925
--- /dev/null
+++ b/bin/swh-hashtree
@@ -0,0 +1,56 @@
+#!/usr/bin/env python3
+
+# Use sample:
+# swh-hashtree --path . --ignore '.svn' --ignore '.git-svn' \
+# --ignore-empty-folders
+# 38f8d2c3a951f6b94007896d0981077e48bbd702
+
+import click
+import os
+
+from swh.model import from_disk, hashutil
+
+
+def combine_filters(*filters):
+ """Combine several ignore filters"""
+ if len(filters) == 0:
+ return from_disk.accept_all_directories
+ elif len(filters) == 1:
+ return filters[0]
+
+ def combined_filter(*args, **kwargs):
+ return all(filter(*args, **kwargs) for filter in filters)
+
+ return combined_filter
+
+
+@click.command()
+@click.option("--path", default=".", help="Optional path to hash.")
+@click.option(
+ "--ignore-empty-folder", is_flag=True, default=False, help="Ignore empty folder."
+)
+@click.option("--ignore", multiple=True, help="Ignore pattern.")
+def main(path, ignore_empty_folder=False, ignore=None):
+
+ filters = []
+ if ignore_empty_folder:
+ filters.append(from_disk.ignore_empty_directories)
+ if ignore:
+ filters.append(
+ from_disk.ignore_named_directories([os.fsencode(name) for name in ignore])
+ )
+
+ try:
+ d = from_disk.Directory.from_disk(
+ path=os.fsencode(path), dir_filter=combine_filters(*filters)
+ )
+ hash = d.hash
+ except Exception as e:
+ print(e)
+ return
+ else:
+ print(hashutil.hash_to_hex(hash))
+
+
+if __name__ == "__main__":
+ main()
diff --git a/bin/swh-revhash b/bin/swh-revhash
new file mode 100755
index 0000000000000000000000000000000000000000..d3a8caf84fab120f7721bffd4d269ee77626982e
--- /dev/null
+++ b/bin/swh-revhash
@@ -0,0 +1,31 @@
+#!/usr/bin/env python3
+
+# Use:
+# swh-revhash 'tree 4b825dc642cb6eb9a060e54bf8d69288fbee4904\nparent 22c0fa5195a53f2e733ec75a9b6e9d1624a8b771\nauthor seanius <seanius@3187e211-bb14-4c82-9596-0b59d67cd7f4> 1138341044 +0000\ncommitter seanius <seanius@3187e211-bb14-4c82-9596-0b59d67cd7f4> 1138341044 +0000\n\nmaking dir structure...\n' # noqa
+# output: 17a631d474f49bbebfdf3d885dcde470d7faafd7
+
+# To compare with git:
+# git-revhash 'tree 4b825dc642cb6eb9a060e54bf8d69288fbee4904\nparent 22c0fa5195a53f2e733ec75a9b6e9d1624a8b771\nauthor seanius <seanius@3187e211-bb14-4c82-9596-0b59d67cd7f4> 1138341044 +0000\ncommitter seanius <seanius@3187e211-bb14-4c82-9596-0b59d67cd7f4> 1138341044 +0000\n\nmaking dir structure...\n' # noqa
+# output: 17a631d474f49bbebfdf3d885dcde470d7faafd7
+
+
+import sys
+
+from swh.model import identifiers, hashutil
+
+
+def revhash(revision_raw):
+ """Compute the revision hash.
+
+ """
+ # HACK: string have somehow their \n expanded to \\n
+ if b"\\n" in revision_raw:
+ revision_raw = revision_raw.replace(b"\\n", b"\n")
+
+ h = hashutil.hash_git_data(revision_raw, "commit")
+ return identifiers.identifier_to_str(h)
+
+
+if __name__ == "__main__":
+ revision_raw = sys.argv[1].encode("utf-8")
+ print(revhash(revision_raw))
diff --git a/docs/.gitignore b/docs/.gitignore
new file mode 100644
index 0000000000000000000000000000000000000000..58a761ead8c3be489f0e4738fac8d2173656ea7f
--- /dev/null
+++ b/docs/.gitignore
@@ -0,0 +1,3 @@
+_build/
+apidoc/
+*-stamp
diff --git a/docs/Makefile b/docs/Makefile
new file mode 100644
index 0000000000000000000000000000000000000000..b97c7532e5b946df72b8641f22f6e3e2ba84602c
--- /dev/null
+++ b/docs/Makefile
@@ -0,0 +1,2 @@
+include ../../swh-docs/Makefile.sphinx
+-include Makefile.local
diff --git a/docs/Makefile.local b/docs/Makefile.local
new file mode 100644
index 0000000000000000000000000000000000000000..fbd18f25c39c2079906b2f347b56eb3cda797e0f
--- /dev/null
+++ b/docs/Makefile.local
@@ -0,0 +1,15 @@
+sphinx/html: images
+sphinx/clean: clean-images
+assets: images
+
+images:
+ make -C images/
+clean-images:
+ make -C images/ clean
+
+.PHONY: images clean-images
+
+
+# Local Variables:
+# mode: makefile
+# End:
diff --git a/docs/_static/.placeholder b/docs/_static/.placeholder
new file mode 100644
index 0000000000000000000000000000000000000000..e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
diff --git a/docs/_templates/.placeholder b/docs/_templates/.placeholder
new file mode 100644
index 0000000000000000000000000000000000000000..e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
diff --git a/docs/cli.rst b/docs/cli.rst
new file mode 100644
index 0000000000000000000000000000000000000000..654111f660fdde7ad129b2658cbeed8633dfe796
--- /dev/null
+++ b/docs/cli.rst
@@ -0,0 +1,6 @@
+Command-line interface
+======================
+
+.. click:: swh.model.cli:identify
+ :prog: swh identify
+ :show-nested:
diff --git a/docs/conf.py b/docs/conf.py
new file mode 100644
index 0000000000000000000000000000000000000000..190deb7e5e29a032ce73bb31f168fe12df300d0d
--- /dev/null
+++ b/docs/conf.py
@@ -0,0 +1 @@
+from swh.docs.sphinx.conf import * # NoQA
diff --git a/docs/data-model.rst b/docs/data-model.rst
new file mode 100644
index 0000000000000000000000000000000000000000..2e311619f52d1d50e9bc0fbdeec89e637db8442d
--- /dev/null
+++ b/docs/data-model.rst
@@ -0,0 +1,262 @@
+.. _data-model:
+
+Data model
+==========
+
+.. note:: The text below is adapted from §7 of the article `Software Heritage:
+ Why and How to Preserve Software Source Code
+ <https://hal.archives-ouvertes.fr/hal-01590958/>`_ (in proceedings of `iPRES
+ 2017 <https://ipres2017.jp/>`_, 14th International Conference on Digital
+ Preservation, by Roberto Di Cosmo and Stefano Zacchiroli), which also
+ provides a more general description of Software Heritage for the digital
+ preservation research community.
+
+In any archival project the choice of the underlying data model—at the logical
+level, independently from how data is actually stored on physical media—is
+paramount. The data model adopted by Software Heritage to represent the
+information that it collects is centered around the notion of *software
+artifact*, described below.
+
+It is important to notice that according to our principles, we must store with
+every software artifact full information on where it has been found
+(provenance), that is also captured in our data model, so we start by providing
+some basic information on the nature of this provenance information.
+
+
+Source code hosting places
+--------------------------
+
+Currently, Software Heritage uses of a curated list of source code hosting
+places to crawl. The most common entries we expect to place in such a list are
+popular collaborative development forges (e.g., GitHub, Bitbucket), package
+manager repositories that host source package (e.g., CPAN, npm), and FOSS
+distributions (e.g., Fedora, FreeBSD). But we may of course allow also more
+niche entries, such as URLs of personal or institutional project collections
+not hosted on major forges.
+
+While currently entirely manual, the curation of such a list might easily be
+semi-automatic, with entries suggested by fellow archivists and/or concerned
+users that want to notify Software Heritage of the need of archiving specific
+pieces of endangered source code. This approach is entirely compatible with
+Web-wide crawling approaches: crawlers capable of detecting the presence of
+source code might enrich the list. In both cases the list will remain curated,
+with (semi-automated) review processes that will need to pass before a hosting
+place starts to be used.
+
+
+Software artifacts
+------------------
+
+Once the hosting places are known, they will need to be periodically looked at
+in order to add to the archive missing software artifacts. Which software
+artifacts will be found there?
+
+In general, each software distribution mechanism hosts multiple releases of a
+given software at any given time. For VCS (Version Control Systems), this is
+the natural behaviour; for software packages, while a single version of a
+package is just a snapshot of the corresponding software product, one can often
+retrieve both current and past versions of the package from its distribution
+site.
+
+By reviewing and generalizing existing VCS and source package formats, we have
+identified the following recurrent artifacts as commonly found at source code
+hosting places. They form the basic ingredients of the Software Heritage
+archive. As the terminology varies quite a bit from technology to technology,
+we provide below both the canonical name used in Software Heritage and popular
+synonyms.
+
+**contents** (AKA "blobs")
+ the raw content of (source code) files as a sequence of bytes, without file
+ names or any other metadata. File contents are often recurrent, e.g., across
+ different versions of the same software, different directories of the same
+ project, or different projects all together.
+
+**directories**
+ a list of named directory entries, each of which pointing to other artifacts,
+ usually file contents or sub-directories. Directory entries are also
+ associated to arbitrary metadata, which vary with technologies, but usually
+ includes permission bits, modification timestamps, etc.
+
+**revisions** (AKA "commits")
+ software development within a specific project is essentially a time-indexed
+ series of copies of a single "root" directory that contains the entire
+ project source code. Software evolves when a developer modifies the content
+ of one or more files in that directory and record their changes.
+
+ Each recorded copy of the root directory is known as a "revision". It points
+ to a fully-determined directory and is equipped with arbitrary metadata. Some
+ of those are added manually by the developer (e.g., commit message), others
+ are automatically synthesized (timestamps, preceding commit(s), etc).
+
+**releases** (AKA "tags")
+ some revisions are more equals than others and get selected by developers as
+ denoting important project milestones known as "releases". Each release
+ points to the last commit in project history corresponding to the release and
+ might carry arbitrary metadata—e.g., release name and version, release
+ message, cryptographic signatures, etc.
+
+
+Additionally, the following crawling-related information are stored as
+provenance information in the Software Heritage archive:
+
+**origins**
+ code "hosting places" as previously described are usually large platforms
+ that host several unrelated software projects. For software provenance
+ purposes it is important to be more specific than that.
+
+ Software origins are fine grained references to where source code artifacts
+ archived by Software Heritage have been retrieved from. They take the form of
+ ``(type, url)`` pairs, where ``url`` is a canonical URL (e.g., the address at
+ which one can ``git clone`` a repository or download a source tarball) and
+ ``type`` the kind of software origin (e.g., git, svn, or dsc for Debian
+ source packages).
+
+..
+ **projects**
+ as commonly intended are more abstract entities that precise software
+ origins. Projects relate together several development resources, including
+ websites, issue trackers, mailing lists, as well as software origins as
+ intended by Software Heritage.
+
+ The debate around the most apt ontologies to capture project-related
+ information for software hasn't settled yet, but the place projects will take
+ in the Software Heritage archive is fairly clear. Projects are abstract
+ entities, which will be arbitrarily nestable in a versioned
+ project/sub-project hierarchy, and that can be associated to arbitrary
+ metadata as well as origins where their source code can be found.
+
+**snapshots**
+ any kind of software origin offers multiple pointers to the "current" state
+ of a development project. In the case of VCS this is reflected by branches
+ (e.g., master, development, but also so called feature branches dedicated to
+ extending the software in a specific direction); in the case of package
+ distributions by notions such as suites that correspond to different maturity
+ levels of individual packages (e.g., stable, development, etc.).
+
+ A "snapshot" of a given software origin records all entry points found there
+ and where each of them was pointing at the time. For example, a snapshot
+ object might track the commit where the master branch was pointing to at any
+ given time, as well as the most recent release of a given package in the
+ stable suite of a FOSS distribution.
+
+**visits**
+ links together software origins with snapshots. Every time an origin is
+ consulted a new visit object is created, recording when (according to
+ Software Heritage clock) the visit happened and the full snapshot of the
+ state of the software origin at the time.
+
+.. note::
+ This model currently records visits as a single point in time. However, the
+ actual visit process is not instantaneous. Loaders can record successive
+ changes to the state of the visit, as their work progresses, as updates to
+ the visit object.
+
+Data structure
+--------------
+
+.. _swh-merkle-dag:
+.. figure:: images/swh-merkle-dag.svg
+ :width: 1024px
+ :align: center
+
+ Software Heritage archive as a Merkle DAG, augmented with crawling
+ information (click to zoom).
+
+
+With all the bits of what we want to archive in place, the next question is how
+to organize them, i.e., which logical data structure to adopt for their
+storage. A key observation for this decision is that source code artifacts are
+massively duplicated. This is so for several reasons:
+
+* code hosting diaspora (i.e., project development moving to the most
+ recent/cool collaborative development technology over time);
+* copy/paste (AKA "vendoring") of parts or entire external FOSS software
+ components into other software products;
+* large overlap between revisions of the same project: usually only a very
+ small amount of files/directories are modified by a single commit;
+* emergence of DVCS (distributed version control systems), which natively work
+ by replicating entire repository copies around. GitHub-style pull requests
+ are the pinnacle of this, as they result in creating an additional repository
+ copy at each change done by a new developer;
+* migration from one VCS to another—e.g., migrations from Subversion to Git,
+ which are really popular these days—resulting in additional copies, but in a
+ different distribution format, of the very same development histories.
+
+These trends seem to be neither stopping nor slowing down, and it is reasonable
+to expect that they will be even more prominent in the future, due to the
+decreasing costs of storage and bandwidth.
+
+For this reason we argue that any sustainable storage layout for archiving
+source code in the very long term should support deduplication, allowing to pay
+for the cost of storing source code artifacts that are encountered more than
+once only once. For storage efficiency, deduplication should be supported for
+all the software artifacts we have discussed, namely: file contents,
+directories, revisions, releases, snapshots.
+
+Realizing that principle, the Software Heritage archive is conceptually a
+single (big) `Merkle Direct Acyclic Graph (DAG)
+<https://en.wikipedia.org/wiki/Merkle_tree>`_, as depicted in Figure
+:ref:`Software Heritage Merkle DAG <swh-merkle-dag>`. In such a graph each of
+the artifacts we have described—from file contents up to entire
+snapshots—correspond to a node. Edges between nodes emerge naturally:
+directory entries point to other directories or file contents; revisions point
+to directories and previous revisions, releases point to revisions, snapshots
+point to revisions and releases. Additionally, each node contains all metadata
+that are specific to the node itself rather than to pointed nodes; e.g., commit
+messages, timestamps, or file names. Note that the structure is really a DAG,
+and not a tree, due to the fact that the line of revisions nodes might be
+forked and merged back.
+
+..
+ directory: fff3cc22cb40f71d26f736c082326e77de0b7692
+ parent: e4feb05112588741b4764739d6da756c357e1f37
+ author: Stefano Zacchiroli <zack@upsilon.cc>
+ date: 1443617461 +0200
+ committer: Stefano Zacchiroli <zack@upsilon.cc>
+ commiter_date: 1443617461 +0200
+ message:
+ objstorage: fix tempfile race when adding objects
+
+ Before this change, two workers adding the same
+ object will end up racing to write <SHA1>.tmp.
+ [...]
+
+ revisionid: 64a783216c1ec69dcb267449c0bbf5e54f7c4d6d
+ A revision node in the Software Heritage DAG
+
+In a Merkle structure each node is identified by an intrinsic identifier
+computed as a cryptographic hash of the node content. In the case of Software
+Heritage identifiers are computed taking into account both node-specific
+metadata and the identifiers of child nodes.
+
+Consider the revision node in the picture whose identifier starts with
+`c7640e08d..`. it points to a directory (identifier starting with
+`45f0c078..`), which has also been archived. That directory contains a full
+copy, at a specific point in time, of a software component—in the example the
+`Hello World <https://forge.softwareheritage.org/source/helloworld/>`_ software
+component available on our forge. The revision node also points to the
+preceding revision node (`43ef7dcd..`) in the project development history.
+Finally, the node contains revision-specific metadata, such as the author and
+committer of the given change, its timestamps, and the message entered by the
+author at commit time.
+
+The identifier of the revision node itself (`c7640e08d..`) is computed as a
+cryptographic hash of a (canonical representation of) all the information shown
+in figure. A change in any of them—metadata and/or pointed nodes—would result
+in an entirely different node identifier. All other types of nodes in the
+Software Heritage archive behave similarly.
+
+The Software Heritage archive inherits useful properties from the underlying
+Merkle structure. In particular, deduplication is built-in. Any software
+artifacts encountered in the wild gets added to the archive only if a
+corresponding node with a matching intrinsic identifier is not already
+available in the graph—file content, commits, entire directories or project
+snapshots are all deduplicated incurring storage costs only once.
+
+Furthermore, as a side effect of this data model choice, the entire development
+history of all the source code archived in Software Heritage—which ambitions to
+match all published source code in the world—is available as a unified whole,
+making emergent structures such as code reuse across different projects or
+software origins, readily available. Further reinforcing the Software Heritage
+use cases, this object could become a veritable "map of the stars" of our
+entire software commons.
diff --git a/docs/iana-swh-template.txt b/docs/iana-swh-template.txt
new file mode 100644
index 0000000000000000000000000000000000000000..a79cf955d0835c8de2eaf3aa066a7d14c73b8fbe
--- /dev/null
+++ b/docs/iana-swh-template.txt
@@ -0,0 +1,39 @@
+(last updated 2020-04-28)
+
+Scheme name: swh
+
+Status: Provisional
+
+Applications/protocols that use this scheme name:
+ Software Heritage: https://www.softwareheritage.org/
+ Software Package Data Exchange: https://spdx.org/
+ NTIA: https://www.ntia.doc.gov/SoftwareTransparency
+ Identifiers.org: http://identifiers.org/
+ Name-to-Thing (N2T): https://n2t.net/
+ HAL: https://hal.archives-ouvertes.fr/
+
+Contact: Stefano Zacchiroli <zack@upsilon.cc>
+
+Change controller: Software Heritage <info@softwareheritage.org>
+
+References:
+
+ Scheme specification: https://docs.softwareheritage.org/devel/swh-model/persistent-identifiers.html
+
+ The Software Heritage project: https://www.softwareheritage.org/
+
+ The Software Heritage archive: https://archive.softwareheritage.org/
+
+ Publications:
+
+ Roberto Di Cosmo, Morane Gruenpeter, Stefano Zacchiroli. Referencing Source
+ Code Artifacts: a Separate Concern in Software Citation. In Computing in
+ Science and Engineering, volume 22, issue 2, pp. 33-43. ISSN 1521-9615,
+ IEEE. March 2020. DOI 10.1109/MCSE.2019.2963148
+
+ Roberto Di Cosmo, Morane Gruenpeter, Stefano Zacchiroli. Identifiers for
+ Digital Objects: the Case of Software Source Code Preservation. In
+ proceedings of iPRES 2018: 15th International Conference on Digital
+ Preservation. September 2018. 10.17605/OSF.IO/KDE56
+
+(file created 2020-04-28)
diff --git a/docs/images/.gitignore b/docs/images/.gitignore
new file mode 100644
index 0000000000000000000000000000000000000000..e9c694ce24364021872ec307b95ca435d82b0aff
--- /dev/null
+++ b/docs/images/.gitignore
@@ -0,0 +1,2 @@
+swh-merkle-dag.pdf
+swh-merkle-dag.svg
diff --git a/docs/images/Makefile b/docs/images/Makefile
new file mode 100644
index 0000000000000000000000000000000000000000..890d6fb994b49f5b0dfcbcc4387b20d2ee194445
--- /dev/null
+++ b/docs/images/Makefile
@@ -0,0 +1,20 @@
+
+MERKLE_DAG = swh-merkle-dag.pdf swh-merkle-dag.svg
+
+BUILD_TARGETS =
+BUILD_TARGETS += $(MERKLE_DAG)
+
+all: $(BUILD_TARGETS)
+
+%.svg: %.dia
+ dia -e $@ $<
+
+%.pdf: %.svg
+ set -e; if [ $$(inkscape --version 2>/dev/null | grep -Eo '[0-9]+' | head -1) -gt 0 ]; then \
+ inkscape -o $@ $< ; \
+ else \
+ inkscape -A $@ $< ; \
+ fi
+
+clean:
+ -rm -f $(BUILD_TARGETS)
diff --git a/docs/images/swh-merkle-dag.dia b/docs/images/swh-merkle-dag.dia
new file mode 100644
index 0000000000000000000000000000000000000000..00edd643bf62df4f65766dcfaaf96be5611ea25b
Binary files /dev/null and b/docs/images/swh-merkle-dag.dia differ
diff --git a/docs/index.rst b/docs/index.rst
new file mode 100644
index 0000000000000000000000000000000000000000..8ad09ac003e8efc69d4682cb57a1e531cffcd3c9
--- /dev/null
+++ b/docs/index.rst
@@ -0,0 +1,15 @@
+.. _swh-model:
+
+Software Heritage - Data model
+==============================
+
+Implementation of the :ref:`data-model` to archive source code artifacts.
+
+.. toctree::
+ :caption: Overview:
+ :titlesonly:
+
+ data-model
+ persistent-identifiers
+ cli
+ /apidoc/swh.model
diff --git a/docs/persistent-identifiers.rst b/docs/persistent-identifiers.rst
new file mode 100644
index 0000000000000000000000000000000000000000..ea1781dd3cf1745d798811f7a10d958f74aa40cc
--- /dev/null
+++ b/docs/persistent-identifiers.rst
@@ -0,0 +1,386 @@
+.. _persistent-identifiers:
+
+=================================================
+SoftWare Heritage persistent IDentifiers (SWHIDs)
+=================================================
+
+**version 1.5, last modified 2020-05-14**
+
+.. contents::
+ :local:
+ :depth: 2
+
+
+Overview
+========
+
+You can point to objects present in the `Software Heritage
+<https://www.softwareheritage.org/>`_ `archive
+<https://archive.softwareheritage.org/>`_ by the means of **SoftWare Heritage
+persistent IDentifiers**, or **SWHIDs** for short, that are guaranteed to
+remain stable (persistent) over time. Their syntax, meaning, and usage is
+described below. Note that they are identifiers and not URLs, even though
+URL-based `resolvers`_ for SWHIDs are also available.
+
+A SWHID consists of two separate parts, a mandatory *core identifier* that can
+point to any software artifact (or "object") available in the Software Heritage
+archive, and an optional list of *qualifiers* that allows to specify the
+context where the object is meant to be seen and point to a subpart of the
+object itself.
+
+Objects come in different types:
+
+* contents
+* directories
+* revisions
+* releases
+* snapshots
+
+Each object is identified by an intrinsic, type-specific object identifier that
+is embedded in its SWHID as described below. The intrinsic identifiers embedded
+in SWHIDs are strong cryptographic hashes computed on the entire set of object
+properties. Together, these identifiers form a `Merkle structure
+<https://en.wikipedia.org/wiki/Merkle_tree>`_, specifically a Merkle `DAG
+<https://en.wikipedia.org/wiki/Directed_acyclic_graph>`_.
+
+See the :ref:`Software Heritage data model <data-model>` for an overview of
+object types and how they are linked together. See
+:py:mod:`swh.model.identifiers` for details on how the intrinsic identifiers
+embedded in SWHIDs are computed.
+
+The optional qualifiers are of two kinds:
+
+* **context qualifiers:** carry information about the context where a given
+ object is meant to be seen. This is particularly important, as the same
+ object can be reached in the Merkle graph following different *paths*
+ starting from different nodes (or *anchors*), and it may have been retrieved
+ from different *origins*, that may evolve between different *visits*
+* **fragment qualifiers:** allow to pinpoint specific subparts of an object
+
+
+Syntax
+======
+
+Syntactically, SWHIDs are generated by the ``<identifier>`` entry point in the
+following grammar:
+
+.. code-block:: bnf
+
+ <identifier> ::= <identifier_core> [ <qualifiers> ] ;
+
+ <identifier_core> ::= "swh" ":" <scheme_version> ":" <object_type> ":" <object_id> ;
+ <scheme_version> ::= "1" ;
+ <object_type> ::=
+ "snp" (* snapshot *)
+ | "rel" (* release *)
+ | "rev" (* revision *)
+ | "dir" (* directory *)
+ | "cnt" (* content *)
+ ;
+ <object_id> ::= 40 * <hex_digit> ; (* intrinsic object id, as hex-encoded SHA1 *)
+ <dec_digit> ::= "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9" ;
+ <hex_digit> ::= <dec_digit> | "a" | "b" | "c" | "d" | "e" | "f" ;
+
+ <qualifiers> := ";" <qualifier> [ <qualifiers> ] ;
+ <qualifier> ::=
+ <context_qualifier>
+ | <fragment_qualifier>
+ ;
+ <context_qualifier> ::=
+ <origin_ctxt>
+ | <visit_ctxt>
+ | <anchor_ctxt>
+ | <path_ctxt>
+ ;
+ <origin_ctxt> ::= "origin" "=" <url_escaped> ;
+ <visit_ctxt> ::= "visit" "=" <identifier_core> ;
+ <anchor_ctxt> ::= "anchor" "=" <identifier_core> ;
+ <path_ctxt> ::= "path" "=" <path_absolute_escaped> ;
+ <fragment_qualifier> ::= "lines" "=" <line_number> ["-" <line_number>] ;
+ <line_number> ::= <dec_digit> + ;
+ <url_escaped> ::= (* RFC 3987 IRI *)
+ <path_absolute_escaped> ::= (* RFC 3987 absolute path *)
+
+Where:
+
+- ``<path_absolute_escaped>`` is an ``<ipath-absolute>`` from `RFC 3987`_, and
+- ``<url_escaped>`` is a `RFC 3987`_ IRI
+
+in either case all occurrences of ``;`` (and ``%``, as required by the RFC)
+have been percent-encoded (as ``%3B`` and ``%25`` respectively). Other
+characters *can* be percent-encoded, e.g., to improve readability and/or
+embeddability of SWHID in other contexts.
+
+.. _RFC 3987: https://tools.ietf.org/html/rfc3987
+
+
+Semantics
+=========
+
+
+Core identifiers
+----------------
+
+``:`` is used as separator between the logical parts of core identifiers. The
+``swh`` prefix makes explicit that these identifiers are related to *SoftWare
+Heritage*. ``1`` (``<scheme_version>``) is the current version of this
+identifier *scheme*. Future editions will use higher version numbers, possibly
+breaking backward compatibility, but without breaking the resolvability of
+SWHIDs that conform to previous versions of the scheme.
+
+A SWHID points to a single object, whose type is explicitly captured by
+``<object_type>``:
+
+* ``snp`` to **snapshots**,
+* ``rel`` to **releases**,
+* ``rev`` to **revisions**,
+* ``dir`` to **directories**,
+* ``cnt`` to **contents**.
+
+The actual object pointed to is identified by the intrinsic identifier
+``<object_id>``, which is a hex-encoded (using lowercase ASCII characters) SHA1
+computed on the content and metadata of the object itself, as follows:
+
+* for **snapshots**, intrinsic identifiers are computed as per
+ :py:func:`swh.model.identifiers.snapshot_identifier`
+
+* for **releases**, as per
+ :py:func:`swh.model.identifiers.release_identifier`
+ that produces the same result as a git release hash
+
+* for **revisions**, as per
+ :py:func:`swh.model.identifiers.revision_identifier`
+ that produces the same result as a git commit hash
+
+* for **directories**, per
+ :py:func:`swh.model.identifiers.directory_identifier`
+ that produces the same result as a git tree hash
+
+* for **contents**, the intrinsic identifier is the ``sha1_git`` hash returned by
+ :py:func:`swh.model.identifiers.content_identifier`, i.e., the SHA1 of a byte
+ sequence obtained by juxtaposing the ASCII string ``"blob"`` (without
+ quotes), a space, the length of the content as decimal digits, a NULL byte,
+ and the actual content of the file.
+
+
+Qualifiers
+----------
+
+``;`` is used as separator between the core identifier and the optional
+qualifiers, as well as between qualifiers. Each qualifier is specified as a
+key/value pair, using ``=`` as a separator.
+
+The following *context qualifiers* are available:
+
+* **origin:** the *software origin* where an object has been found or observed
+ in the wild, as an URI;
+
+* **visit:** the core identifier of a *snapshot* corresponding to a specific
+ *visit* of a repository containing the designated object;
+
+* **anchor:** a *designated node* in the Merkle DAG relative to which a *path
+ to the object* is specified, as the core identifier of a directory, a
+ revision, a release or a snapshot;
+
+* **path:** the *absolute file path*, from the *root directory* associated to
+ the *anchor node*, to the object; when the anchor denotes a directory or a
+ revision, and almost always when it's a release, the root directory is
+ uniquely determined; when the anchor denotes a snapshot, the root directory
+ is the one pointed to by ``HEAD`` (possibly indirectly), and undefined if
+ such a reference is missing;
+
+The following *fragment qualifier* is available:
+
+* **lines:** *line number(s)* of interest, usually within a content object
+
+We recommend to equip identifiers meant to be shared with as many qualifiers as
+possible. While qualifiers may be listed in any order, it is good practice to
+present them in the order given above, i.e., ``origin``, ``visit``, ``anchor``,
+``path``, ``lines``. Redundant information should be omitted: for example, if
+the *visit* is present, and the *path* is relative to the snapshot indicated
+there, then the *anchor* qualifier is superfluous; similarly, if the *path* is
+empty, it may be omitted.
+
+
+Interoperability
+================
+
+
+URI scheme
+----------
+
+The ``swh`` URI scheme is registered at IANA for SWHIDs. The present documents
+constitutes the scheme specification for such URI scheme.
+
+
+Git compatibility
+-----------------
+
+SWHIDs for contents, directories, revisions, and releases are, at present,
+compatible with the `Git <https://git-scm.com/>`_ way of `computing identifiers
+<https://git-scm.com/book/en/v2/Git-Internals-Git-Objects>`_ for its objects.
+The ``<object_id>`` part of a SWHID for a content object is the Git blob
+identifier of any file with the same content; for a revision it is the Git
+commit identifier for the same revision, etc. This is not the case for
+snapshot identifiers, as Git does not have a corresponding object type.
+
+Note that Git compatibility is incidental and is not guaranteed to be
+maintained in future versions of this scheme (or Git).
+
+
+Examples
+========
+
+
+Core identifiers
+----------------
+
+* ``swh:1:cnt:94a9ed024d3859793618152ea559a168bbcbb5e2`` points to the content
+ of a file containing the full text of the GPL3 license
+
+* ``swh:1:dir:d198bc9d7a6bcf6db04f476d29314f157507d505`` points to a directory
+ containing the source code of the Darktable photography application as it was
+ at some point on 4 May 2017
+
+* ``swh:1:rev:309cf2674ee7a0749978cf8265ab91a60aea0f7d`` points to a commit in
+ the development history of Darktable, dated 16 January 2017, that added
+ undo/redo supports for masks
+
+* ``swh:1:rel:22ece559cc7cc2364edc5e5593d63ae8bd229f9f`` points to Darktable
+ release 2.3.0, dated 24 December 2016
+
+* ``swh:1:snp:c7c108084bc0bf3d81436bf980b46e98bd338453`` points to a snapshot
+ of the entire Darktable Git repository taken on 4 May 2017 from GitHub
+
+
+Identifiers with qualifiers
+---------------------------
+
+* The following `SWHID
+ <https://archive.softwareheritage.org/swh:1:cnt:4d99d2d18326621ccdd70f5ea66c2e2ac236ad8b;origin=https://gitorious.org/ocamlp3l/ocamlp3l_cvs.git;visit=swh:1:snp:d7f1b9eb7ccb596c2622c4780febaa02549830f9;anchor=swh:1:rev:2db189928c94d62a3b4757b3eec68f0a4d4113f0;path=/Examples/SimpleFarm/simplefarm.ml;lines=9-15>`_
+ denotes the lines 9 to 15 of a file content that can be found at absolute
+ path ``/Examples/SimpleFarm/simplefarm.ml`` from the root directory of the
+ revision ``swh:1:rev:2db189928c94d62a3b4757b3eec68f0a4d4113f0`` that is
+ contained in the snapshot
+ ``swh:1:snp:d7f1b9eb7ccb596c2622c4780febaa02549830f9`` taken from the origin
+ ``https://gitorious.org/ocamlp3l/ocamlp3l_cvs.git``:
+
+.. code-block:: url
+
+ swh:1:cnt:4d99d2d18326621ccdd70f5ea66c2e2ac236ad8b;
+ origin=https://gitorious.org/ocamlp3l/ocamlp3l_cvs.git;
+ visit=swh:1:snp:d7f1b9eb7ccb596c2622c4780febaa02549830f9;
+ anchor=swh:1:rev:2db189928c94d62a3b4757b3eec68f0a4d4113f0;
+ path=/Examples/SimpleFarm/simplefarm.ml;
+ lines=9-15
+
+* Here is an example of a `SWHID
+ <https://archive.softwareheritage.org/swh:1:cnt:f10371aa7b8ccabca8479196d6cd640676fd4a04;origin=https://github.com/web-platform-tests/wpt;visit=swh:1:snp:b37d435721bbd450624165f334724e3585346499;anchor=swh:1:rev:259d0612af038d14f2cd889a14a3adb6c9e96d96;path=/html/semantics/document-metadata/the-meta-element/pragma-directives/attr-meta-http-equiv-refresh/support/x%3Burl=foo/>`_
+ with a file path that requires percent-escaping:
+
+.. code-block:: url
+
+ swh:1:cnt:f10371aa7b8ccabca8479196d6cd640676fd4a04;
+ origin=https://github.com/web-platform-tests/wpt;
+ visit=swh:1:snp:b37d435721bbd450624165f334724e3585346499;
+ anchor=swh:1:rev:259d0612af038d14f2cd889a14a3adb6c9e96d96;
+ path=/html/semantics/document-metadata/the-meta-element/pragma-directives/attr-meta-http-equiv-refresh/support/x%3Burl=foo/
+
+
+Implementation
+==============
+
+
+Computing
+---------
+
+An important property of any SWHID is that its core identifier is *intrinsic*:
+it can be *computed from the object itself*, without having to rely on any
+third party. An implementation of SWHID that allows to do so locally is the
+`swh identify <https://docs.softwareheritage.org/devel/swh-model/cli.html>`_
+tool, available from the `swh.model <https://pypi.org/project/swh.model/>`_
+Python package under the GPL license.
+
+SWHIDs are also automatically computed by Software Heritage for all archived
+objects as part of its archival activity, and can be looked up via the project
+`Web interface <https://archive.softwareheritage.org>`_.
+
+This has various practical implications:
+
+* when a software artifact is obtained from Software Heritage by resolving a
+ SWHID, it is straightforward to verify that it is exactly the intended one:
+ just compute the core identifier from the artefact itself, and check that it
+ is the same as the core identifier part of the SHWID
+
+* the core identifier of a software artifact can be computed *before* its
+ archival on Software Heritage
+
+
+Resolvers
+---------
+
+
+Software Heritage resolver
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+SWHIDs can be resolved using the Software Heritage `Web interface
+<https://archive.softwareheritage.org>`_. In particular, the **root endpoint**
+``/`` can be given a SWHID and will lead to the browsing page of the
+corresponding object, like this:
+``https://archive.softwareheritage.org/<identifier>``.
+
+A **dedicated** ``/resolve`` **endpoint** of the Software Heritage `Web API
+<https://archive.softwareheritage.org/api/>`_ is also available to
+programmatically resolve SWHIDs; see: :http:get:`/api/1/resolve/(swhid)/`.
+
+Examples:
+
+* `<https://archive.softwareheritage.org/swh:1:cnt:94a9ed024d3859793618152ea559a168bbcbb5e2>`_
+* `<https://archive.softwareheritage.org/swh:1:dir:d198bc9d7a6bcf6db04f476d29314f157507d505>`_
+* `<https://archive.softwareheritage.org/api/1/resolve/swh:1:rev:309cf2674ee7a0749978cf8265ab91a60aea0f7d>`_
+* `<https://archive.softwareheritage.org/api/1/resolve/swh:1:rel:22ece559cc7cc2364edc5e5593d63ae8bd229f9f>`_
+* `<https://archive.softwareheritage.org/api/1/resolve/swh:1:snp:c7c108084bc0bf3d81436bf980b46e98bd338453>`_
+* `<https://archive.softwareheritage.org/swh:1:cnt:4d99d2d18326621ccdd70f5ea66c2e2ac236ad8b;origin=https://gitorious.org/ocamlp3l/ocamlp3l_cvs.git;visit=swh:1:snp:d7f1b9eb7ccb596c2622c4780febaa02549830f9;anchor=swh:1:rev:2db189928c94d62a3b4757b3eec68f0a4d4113f0;path=/Examples/SimpleFarm/simplefarm.ml;lines=9-15>`_
+* `<https://archive.softwareheritage.org/swh:1:cnt:f10371aa7b8ccabca8479196d6cd640676fd4a04;origin=https://github.com/web-platform-tests/wpt;visit=swh:1:snp:b37d435721bbd450624165f334724e3585346499;anchor=swh:1:rev:259d0612af038d14f2cd889a14a3adb6c9e96d96;path=/html/semantics/document-metadata/the-meta-element/pragma-directives/attr-meta-http-equiv-refresh/support/x%3Burl=foo/>`_
+
+
+Third-party resolvers
+~~~~~~~~~~~~~~~~~~~~~
+
+The following **third party resolvers** support SWHID resolution:
+
+* `Identifiers.org <https://identifiers.org>`_; see:
+ `<http://identifiers.org/swh/>`_ (registry identifier `MIR:00000655
+ <https://www.ebi.ac.uk/miriam/main/datatypes/MIR:00000655>`_).
+
+* `Name-to-Thing (N2T) <https://n2t.net/>`_
+
+Note that resolution via Identifiers.org currently only supports *core
+identifiers* due to `syntactic incompatibilities with qualifiers
+<http://identifiers.org/documentation#custom_requests>`_.
+
+Examples:
+
+* `<https://identifiers.org/swh:1:cnt:94a9ed024d3859793618152ea559a168bbcbb5e2>`_
+* `<https://identifiers.org/swh:1:dir:d198bc9d7a6bcf6db04f476d29314f157507d505>`_
+* `<https://identifiers.org/swh:1:rev:309cf2674ee7a0749978cf8265ab91a60aea0f7d>`_
+* `<https://n2t.net/swh:1:rel:22ece559cc7cc2364edc5e5593d63ae8bd229f9f>`_
+* `<https://n2t.net/swh:1:snp:c7c108084bc0bf3d81436bf980b46e98bd338453>`_
+* `<https://n2t.net/swh:1:cnt:4d99d2d18326621ccdd70f5ea66c2e2ac236ad8b;origin=https://gitorious.org/ocamlp3l/ocamlp3l_cvs.git;visit=swh:1:snp:d7f1b9eb7ccb596c2622c4780febaa02549830f9;anchor=swh:1:rev:2db189928c94d62a3b4757b3eec68f0a4d4113f0;path=/Examples/SimpleFarm/simplefarm.ml;lines=9-15>`_
+* `<https://n2t.net/swh:1:cnt:f10371aa7b8ccabca8479196d6cd640676fd4a04;origin=https://github.com/web-platform-tests/wpt;visit=swh:1:snp:b37d435721bbd450624165f334724e3585346499;anchor=swh:1:rev:259d0612af038d14f2cd889a14a3adb6c9e96d96;path=/html/semantics/document-metadata/the-meta-element/pragma-directives/attr-meta-http-equiv-refresh/support/x%3Burl=foo/>`_
+
+
+References
+==========
+
+* Roberto Di Cosmo, Morane Gruenpeter, Stefano Zacchiroli. `Identifiers for
+ Digital Objects: the Case of Software Source Code Preservation
+ <https://hal.archives-ouvertes.fr/hal-01865790v4>`_. In Proceedings of `iPRES
+ 2018 <https://ipres2018.org/>`_: 15th International Conference on Digital
+ Preservation, Boston, MA, USA, September 2018, 9 pages.
+
+* Roberto Di Cosmo, Morane Gruenpeter, Stefano Zacchiroli. `Referencing Source
+ Code Artifacts: a Separate Concern in Software Citation
+ <https://arxiv.org/abs/2001.08647>`_. In Computing in Science and
+ Engineering, volume 22, issue 2, pages 33-43. ISSN 1521-9615,
+ IEEE. March 2020.
diff --git a/mypy.ini b/mypy.ini
new file mode 100644
index 0000000000000000000000000000000000000000..71ae7f3b03a19ac782e54450a52d27110746658b
--- /dev/null
+++ b/mypy.ini
@@ -0,0 +1,29 @@
+[mypy]
+namespace_packages = True
+warn_unused_ignores = True
+
+# 3rd party libraries without stubs (yet)
+
+[mypy-attrs_strict.*] # a bit sad, but...
+ignore_missing_imports = True
+
+[mypy-deprecated.*]
+ignore_missing_imports = True
+
+[mypy-django.*] # false positive, only used my hypotesis' extras
+ignore_missing_imports = True
+
+[mypy-dulwich.*]
+ignore_missing_imports = True
+
+[mypy-iso8601.*]
+ignore_missing_imports = True
+
+[mypy-pkg_resources.*]
+ignore_missing_imports = True
+
+[mypy-pyblake2.*]
+ignore_missing_imports = True
+
+[mypy-pytest.*]
+ignore_missing_imports = True
diff --git a/pytest.ini b/pytest.ini
new file mode 100644
index 0000000000000000000000000000000000000000..c8e8c197ec42d9116539ae8d5cdedf12a4678a6b
--- /dev/null
+++ b/pytest.ini
@@ -0,0 +1,5 @@
+[pytest]
+addopts = --doctest-modules
+norecursedirs = docs
+markers =
+ fs: tests that involve filesystem ios
diff --git a/requirements.txt b/requirements.txt
index a5d782c4eb5084b6a5f9307fa80bdd4c75567e59..255afbed06bc82e9ecd73a18455249217f18374a 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -8,4 +8,4 @@ hypothesis
iso8601
python-dateutil
typing_extensions
-vcversioner
+
diff --git a/setup.py b/setup.py
index f2432ac311654135b4c0851fe322f892cd1121d9..ecaac1058cb3dc356fe45ef910d5bed157dbc11b 100755
--- a/setup.py
+++ b/setup.py
@@ -47,7 +47,8 @@ setup(
author_email="swh-devel@inria.fr",
url="https://forge.softwareheritage.org/diffusion/DMOD/",
packages=find_packages(),
- setup_requires=["vcversioner"],
+ setup_requires=["setuptools-scm"],
+ use_scm_version=True,
install_requires=(
parse_requirements() + parse_requirements("swh") + blake2_requirements
),
@@ -55,7 +56,6 @@ setup(
"cli": parse_requirements("cli"),
"testing": parse_requirements("test"),
},
- vcversioner={},
include_package_data=True,
entry_points="""
[console_scripts]
diff --git a/swh.model.egg-info/PKG-INFO b/swh.model.egg-info/PKG-INFO
index e64ece76688e735e99bfc5f05278259220baf817..1caa4b57998c525be0d28b1da197960e4df8c9ff 100644
--- a/swh.model.egg-info/PKG-INFO
+++ b/swh.model.egg-info/PKG-INFO
@@ -1,6 +1,6 @@
Metadata-Version: 2.1
Name: swh.model
-Version: 0.6.1
+Version: 0.6.4
Summary: Software Heritage data model
Home-page: https://forge.softwareheritage.org/diffusion/DMOD/
Author: Software Heritage developers
diff --git a/swh.model.egg-info/SOURCES.txt b/swh.model.egg-info/SOURCES.txt
index 763a95cb9133c6375cceb9709b9ae918df62c525..90423a1aae99e120c12d7bd1203d5be5c9303399 100644
--- a/swh.model.egg-info/SOURCES.txt
+++ b/swh.model.egg-info/SOURCES.txt
@@ -1,13 +1,40 @@
+.gitignore
+.pre-commit-config.yaml
+AUTHORS
+CODE_OF_CONDUCT.md
+CONTRIBUTORS
+LICENSE
MANIFEST.in
Makefile
+Makefile.local
README.md
+mypy.ini
pyproject.toml
+pytest.ini
requirements-cli.txt
requirements-test.txt
requirements.txt
setup.cfg
setup.py
+tox.ini
version.txt
+bin/git-revhash
+bin/swh-hashtree
+bin/swh-revhash
+docs/.gitignore
+docs/Makefile
+docs/Makefile.local
+docs/cli.rst
+docs/conf.py
+docs/data-model.rst
+docs/iana-swh-template.txt
+docs/index.rst
+docs/persistent-identifiers.rst
+docs/_static/.placeholder
+docs/_templates/.placeholder
+docs/images/.gitignore
+docs/images/Makefile
+docs/images/swh-merkle-dag.dia
swh/__init__.py
swh.model.egg-info/PKG-INFO
swh.model.egg-info/SOURCES.txt
diff --git a/swh.model.egg-info/requires.txt b/swh.model.egg-info/requires.txt
index 499cf97ac0e4d349938d64fafa2b5da63d52b50a..e257baf1120c947eeee8ed54be398131a74f4be9 100644
--- a/swh.model.egg-info/requires.txt
+++ b/swh.model.egg-info/requires.txt
@@ -5,7 +5,6 @@ hypothesis
iso8601
python-dateutil
typing_extensions
-vcversioner
[:python_version < "3.6"]
pyblake2
diff --git a/swh/model/model.py b/swh/model/model.py
index dd73bf99b6a8f52aca76cee43028f1ebf4e9d424..ff11f1cb2e72cd74dacd6cac54c8b30a131f1595 100644
--- a/swh/model/model.py
+++ b/swh/model/model.py
@@ -736,8 +736,6 @@ class MetadataAuthority(BaseModel):
"""Represents an entity that provides metadata about an origin or
software artifact."""
- object_type: Final = "metadata_authority"
-
type = attr.ib(type=MetadataAuthorityType, validator=type_validator())
url = attr.ib(type=str, validator=type_validator())
metadata = attr.ib(
@@ -764,8 +762,6 @@ class MetadataFetcher(BaseModel):
"""Represents a software component used to fetch metadata from a metadata
authority, and ingest them into the Software Heritage archive."""
- object_type: Final = "metadata_fetcher"
-
name = attr.ib(type=str, validator=type_validator())
version = attr.ib(type=str, validator=type_validator())
metadata = attr.ib(
@@ -795,8 +791,6 @@ class MetadataTargetType(Enum):
@attr.s(frozen=True)
class RawExtrinsicMetadata(BaseModel):
- object_type: Final = "raw_extrinsic_metadata"
-
# target object
type = attr.ib(type=MetadataTargetType, validator=type_validator())
id = attr.ib(type=Union[str, SWHID], validator=type_validator())
diff --git a/tox.ini b/tox.ini
new file mode 100644
index 0000000000000000000000000000000000000000..f0adbaf78eca987fa2f912b951bc2b58a36af673
--- /dev/null
+++ b/tox.ini
@@ -0,0 +1,34 @@
+[tox]
+envlist=black,flake8,mypy,py3
+
+[testenv]
+extras =
+ testing
+deps =
+ pytest-cov
+commands =
+ pytest --cov={envsitepackagesdir}/swh/model \
+ {envsitepackagesdir}/swh/model \
+ --cov-branch {posargs}
+
+[testenv:black]
+skip_install = true
+deps =
+ black
+commands =
+ {envpython} -m black --check swh
+
+[testenv:flake8]
+skip_install = true
+deps =
+ flake8
+commands =
+ {envpython} -m flake8
+
+[testenv:mypy]
+extras =
+ testing
+deps =
+ mypy
+commands =
+ mypy swh