The SpatioTemporal Asset Catalog specification is under active development. The goal is to get to a small, flexible stable release that can be extended in a variety of ways. The core development team aims to release early and often, which generally has meant a new release between two and four months since the previous one.
The master branch aims to always be stable, meaning that all the pieces of the specification are consistent and well
explained, and all the examples are consistent with the specification. The dev branch is a place of active development,
where a new change in one part of the spec might not yet be fully updated everywhere else. The team uses the
stac-spec issue tracker to identify and track all that will be done for
a release. Once all the major issues are resolved the core team makes sure everything is consistent across the spec and
examples.
Any changes to the spec must be made as pull requests to the dev branch. Anyone is welcome and encouraged to bring ideas
and improvements, to the issue tracker or (ideally) as pull requests. To merge a new pull request the work must be reviewed
by at least two members of the STAC spec core team (who have write access to the main repository). It also must pass the
Continuous Integration testing (right now it is minimal, but it will expand).
- Note The development process will continue to evolve as the specification matures. 0.6.0 introduced Continuous
Integration, and once it is full validating everything and the spec is more mature then we will aim to have
devbranch always in a consistent state.
To release a new version of the STAC spec the following list of tasks must be done.
- Update Issue Tracker: Each release has a milestone in the github issue tracker, and before a release is done all open issues that are filed against it should be reviewed. All issues do not need to be completed, but the core release team should all review the issues to make sure that the critical ones for the release have been addressed. Issues that aren't seen as essential should be moved to future releases, so that there are no open issues against the milestone.
- Agreement from core team: The core STAC team should meet (on phone or on gitter) and decided that the release is ready. This should include review of the issues, as well as looking at the spec holistically, to make sure the new changes keep with a coherent whole.
- Validate Examples: All examples given in the specification should be programmatically validated against their relevant schema. For 0.6.0-RC1 and before this is a manual process, but with CirclCI in place this should happen automatically. But someone should still review that all the schemas have been updated and align with the current state of the spec, as that can not happen automatically.
- Final Spec Read Through: There should be a final read through of the core specification to make sure it makes sense and there are no typos, errors, etc.
- Update the version numbers: There are several places in the spec that use the version number in text or a link. These include the readme, and the openapi specs. Right now the best thing to do is just a search & replace. Hopefully in the future there will be scripts or continuous integration to do this.
- Update the Changelog: The changelog should be reviewed to make sure it includes all major improvements in the release. And anything in 'unreleased' section should move to the version of the spec to be released.
- Merge dev to master: As there is no 'build' process, since the specification is the markdown files in the github
repository, the key step in a release is to merge the
devbranch intomaster, asmasteris the current stable state of the spec. - Check Online API Docs: Check to make sure the online API docs reflect the release at https://stacspec.org/STAC-api.html and https://stacspec.org/STAC-ext-api.html (this step may go away once we are confident this works well)
- Release on Github: The final step to create the release is to add a new 'release' on https://github.com/radiantearth/stac-spec/releases. This should use a tag like the others, with a 'v' prefix and then the release number, like v0.5.2. The changelog should be copied over to be the release notes, and then also include a link to the full milestone of everything closed in the issue tracker.
- Promote the release: A blog post and tweet should be composed and sent out, and then inform those in the gitter channel to post / promote it.
Before any release that has major changes (made as a judgement call by the core contributors) there should be a 'release candidate' to ensure the wider community of implementors can try it out and catch any errors before a full release. It is only through actual implementations that we can be sure the new spec version is good, so this step is essential if there are major changes. The release should proceed as normal, but called vX.Y.Z-RC1. The core STAC community should be told and encouraged to update their implementations. At least 2 implementations should be updated to the new specification before there is a real release. And ideally a client like STAC Browser is also updated. This provides the core sanity check. If there are changes or fixes to the spec or schemas needed from their feedback then make fixes and do RC2. If it is just fixes to the examples or tooling then no additional RC is needed. After there is no more changes to spec or schemas then the release process should be done on master, with no changes to the spec - just updating the version numbers.
The goal of STAC is to have a Project Steering Committee of core contributors, representing diverse organizations and implementations. To bootstrap Chris Holmes is the Benevolent Dictator for Life or until a PSC is formed, so we don't get stuck waiting for votes when there is not enough activity.
The longer term goal is to contribute STAC spec to the Open Geospatial Consortium, and indeed to align as much as possible with their next generation spec.