Many changes including bug fixes, documentation improvements and minor features can be implemented and reviewed via the normal GitHub pull request workflow.

Some changes though are "substantial", and we ask that these be put through a bit of a design approval process and produce a consensus among the Unity Multiplayer team and the community.

The "RFC" (request for comments) process is intended to provide a consistent and controlled path for new features to enter the Unity Multiplayer, so that both the Unity Multiplayer team and the community can be confident about the direction the project is evolving in.

Active RFC List →

You need to follow this process if you intend to make "substantial" changes to Unity Multiplayer projects, documentation or the RFC process itself. What constitutes a "substantial" change is evolving based on community norms and varies depending on what part of the ecosystem you are proposing to change, but may include the following:

• Any framework API or internal behavior change that is not a bugfix
• Introducing a new feature and/or deprecating an existing feature
• Additional built-in features, components and/or extensions
• A code refactor touching a large part of the codebase

Some changes do not require an RFC:

• Bugfix/hotfix/patch, minimal local refactorings and other minor improvements
• Reorganizing directories, moving and renaming files without changing their meanings
• Typo fixes, commentary updates, documentation changes

If you submit a pull request to implement a new feature without going through the RFC process, it may be closed with a polite request to submit an RFC first.

A hastily-proposed RFC can hurt its chances of acceptance. Low quality proposals, proposals for previously-rejected features, or those that don't fit into the near-term roadmap, may be quickly rejected, which can be demotivating for the unprepared contributor. Laying some groundwork ahead of the RFC can make the process smoother.

Although there is no single way to prepare for submitting an RFC, it is generally a good idea to pursue feedback from other project developers beforehand, to ascertain that the RFC may be desirable; having a consistent impact on the project requires concerted effort toward consensus-building.

Our main communication channel for discussions about RFCs and the development of MLAPI is the MLAPI Discord. The #rfc-discussion channel can be used to get feedback for RFC ideas or to discuss already existing RFC proposals.

As a rule of thumb, receiving encouraging feedback from long-standing project developers, and particularly members of the relevant project's team is a good indication that the RFC is worth pursuing.

In short, to get a major feature added to Unity Multiplayer, one must first get the RFC merged into the RFC repository as a markdown file. At that point the RFC is "active" and may be implemented with the goal of eventual inclusion into Unity Multiplayer.

• Fork the RFC repo RFC repository.
• Copy 0000-template.md to text/0000-my-feature.md (where "my-feature" is descriptive). Don't assign an RFC number yet; This is going to be the PR number and we'll rename the file accordingly if the RFC is accepted.
• Make sure to put all relevant materials (if any) such as images, PDFs etc. under a folder named exactly as markdown document filename without extension (e.g. markdown document: text/0000-my-feature.md and materials folder: text/0000-my-feature/) in your upcoming PR.
• Do not include implementations including POCs, prototypes, demos, either polished or unpolished works. They are all subject to be reviewed under a different PR on their respective repositories with the links between.
• Fill in the RFC. Put care into the details: RFCs that do not present convincing motivation, demonstrate lack of understanding of the design's impact, or are disingenuous about the drawbacks or alternatives tend to be poorly-received.
• Submit a pull request. As a pull request the RFC will receive design feedback from the larger community, and the author should be prepared to revise it in response.
• Each pull request will be labeled with the most relevant Unity Multiplayer team, which will lead to its being triaged by that team in a future meeting and assigned to a member of the subteam.
• Build consensus and integrate feedback. RFCs that have broad support are much more likely to make progress than those that don't receive any comments. Feel free to reach out to the RFC assignee in particular to get help identifying stakeholders and obstacles.
• The Unity Multiplayer team will discuss the RFC pull request, as much as possible in the comment thread of the pull request itself. Offline discussion will be summarized on the pull request comment thread.
• RFCs rarely go through this process unchanged, especially as alternatives and drawbacks are shown. You can make edits, big and small, to the RFC to clarify or change the design, but make changes as new commits to the pull request, and leave a comment on the pull request explaining your changes. Specifically, do not squash or rebase commits after they are visible on the pull request.
• At some point, a member of the Unity Multiplayer team will propose a "motion for final comment period" (FCP), along with a disposition for the RFC (merge, close, or postpone).
  • This step is taken when enough of the tradeoffs have been discussed that the Unity Multiplayer team is in a position to make a decision. That does not require consensus amongst all participants in the RFC thread (which is usually impossible). However, the argument supporting the disposition on the RFC needs to have already been clearly articulated, and there should not be a strong consensus against that position outside of the Unity Multiplayer team. Unity Multiplayer team members use their best judgment in taking this step, and the FCP itself ensures there is ample time and notification for stakeholders to push back if it is made prematurely.
  • For RFCs with lengthy discussion, the motion to FCP is usually preceded by a summary comment trying to lay out the current state of the discussion and major tradeoffs/points of disagreement.
  • Before actually entering FCP, all members of the Unity Multiplayer team must sign off; this is often the point at which many Unity Multiplayer team members first review the RFC in full depth.
• The FCP lasts ten calendar days, so that it is open for at least 5 business days. This way all stakeholders have a chance to lodge any final objections before a decision is reached.
• In most cases, the FCP period is quiet, and the RFC is either merged or closed. However, sometimes substantial new arguments or ideas are raised, the FCP is canceled, and the RFC goes back into development mode.

Once an RFC becomes "active" then authors may implement it and submit the feature as a pull request to the Unity Multiplayer repo. Being "active" is not a rubber stamp, and in particular still does not mean the feature will ultimately be merged; it does mean that in principle all the major stakeholders have agreed to the feature and are amenable to merging it.

Furthermore, the fact that a given RFC has been accepted and is "active" implies nothing about what priority is assigned to its implementation, nor does it imply anything about whether a Unity Multiplayer developer has been assigned the task of implementing the feature. While it is not necessary that the author of the RFC also write the implementation, it is by far the most effective way to see an RFC through to completion: authors should not expect that other project developers will take on responsibility for implementing their accepted feature.

Modifications to "active" RFCs can be done in follow-up pull requests. We strive to write each RFC in a manner that it will reflect the final design of the feature; but the nature of the process means that we cannot expect every merged RFC to actually reflect what the end result will be at the time of the next major release.

In general, once accepted, RFCs should not be substantially changed. Only very minor changes should be submitted as amendments. More substantial changes should be new RFCs, with a note added to the original RFC. Exactly what counts as a "very minor change" is up to the Unity Multiplayer to decide.

While the RFC pull request is up, the Unity Multiplayer team may schedule meetings with the author and/or relevant stakeholders to discuss the issues in greater detail, and in some cases the topic may be discussed at a Unity Multiplayer team meeting. In either case a summary from the meeting will be posted back to the RFC pull request.

Unity Multiplayer team makes final decisions about RFCs after the benefits and drawbacks are well understood. These decisions can be made at any time, but the Unity Multiplayer team will regularly issue decisions. When a decision is made, the RFC pull request will either be merged or closed. In either case, if the reasoning is not clear from the discussion in thread, the Unity Multiplayer team will add a comment describing the rationale for the decision.

Some accepted RFCs represent vital features that need to be implemented right away. Other accepted RFCs can represent features that can wait until some arbitrary developer feels like doing the work. Every accepted RFC has an associated issue tracking its implementation in the Unity Multiplayer repository; thus that associated issue can be assigned a priority via the triage process that the team uses for all issues in the Unity Multiplayer repository.

The author of an RFC is not obligated to implement it. Of course, the RFC author (like any other developer) is welcome to post an implementation for review after the RFC has been accepted.

If you are interested in working on the implementation for an "active" RFC, but cannot determine if someone else is already working on it, feel free to ask (e.g. by leaving a comment on the associated issue).

// todo

The process is intended to be as lightweight as reasonable for the present circumstances. As usual, we are trying to let the process be driven by consensus and community norms, not impose more structure than necessary.

When you open a pull request, you will be asked to acknowledge our Contributor License Agreement. We allow both individual contributions and contributions made on behalf of companies. We use an open source tool called CLA assistant. If you have any questions on our CLA, please submit an issue.

MIT License

Unity Multiplayer's RFC process owes its inspiration to the Rust RFC process.