GEPs: GrADS Enhancement Proposals

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What is a GEP?

GEP stands for GrADS Enhancement Proposal and borrows heavily from PEP, the Python Engancement Proposal. Like PEP, a GEP is a design document providing information to the OpenGrADS development community, or describing a new feature for GrADS or its processes or environment. The GEP should provide a concise technical specification of the feature and a rationale for the feature.

We intend GEPs to be the primary mechanisms for proposing new features, for collecting community input on an issue, and for documenting the design decisions that have gone into the OpenGrADS interfaces and extensions, as well as contributions from the OpenGrADS community to the core GrADS engine maintained by COLA. (For conciseness, in the remainder of this document we will use the term OpenGrADS to refer to both the core GrADS application as well as the interfaces and extensions being developed by the OpenGrADS project.) The GEP author is responsible for building consensus within the community and documenting dissenting opinions. The adoption of new features in the core GrADS application is at the sole discretion of COLA, the maintainers of GrADS. The OpenGrADS GEPs only provide a process for collecting these contributions from our community.

Because the GEPs are maintained under MediaWiki, their revision history is the historical record of the feature proposal.

How GEPs differ from PEPs

Although similar in philosophy, given the size of the OpenGrADS development community, GEPs will be maintained in a somewhat less formal way than PEPs. In particular,

  • GEPs will maintained directly on the OpenGrADS development wiki
  • Developers with access to the wiki will use the 'discussion feature of MediWiki to post comments and iterate on the document.
  • End-users with no wiki access should post commends on the OpenGrADS open-discussion forum, where than can request write access to the wiki.

GEP Types

There are three kinds of GEP:

  1. A Standards Track GEP describes a new feature or implementation for OpenGrADS.
  2. An Informational GEP describes a GrADS design issue, or provides general guidelines or information to the OpenGrADS community, but does not propose a new feature. Informational PEPs do not necessarily represent a OpenGrADS community consensus or recommendation, so users and implementors are free to ignore Informational PEPs or follow their advice.
  3. A Process GEP describes a process surrounding OpenGrADS, or proposes a change to (or an event in) a process. Process PEPs are like Standards Track PEPs but apply to areas other than the OpenGrADS itself. They may propose an implementation, but not to OpenGrADS's codebase; they often require community consensus; unlike Informational GEPs, they are more than recommendations, and users are typically not free to ignore them. Examples include release schedules, procedures, guidelines, changes to the decision-making process, and changes to the tools or environment used in OpenGrADS development.

GEP Work Flow

The GEP editors assign GEP numbers and change their status. The current GEP editors are the current Project Admins for the OpenGRADS Project at Sourceforge. Please send all GEP-related email to <[1]>. Each GEP must have a champion -- someone who writes the GEP using the style and format described below, shepherds the discussions in the appropriate forums, and attempts to build community consensus around the idea. The GEP champion (a.k.a. Author) should first attempt to ascertain whether the idea is GEP-able. Posting to the OpenGrADS developer list is the recommended starting point. Small enhancements or patches often don't need a GEP and can be injected into the OpenGrADS development work flow with a patch submission to the OpenGrADS developer list.

  1. The GEP process begins with a new idea for OpenGrADS. It is highly recommended that a single GEP contain a single key proposal or new idea. The more focussed the GEP, the more successful it tends to be. The GEP editor reserves the right to reject GEP proposals if they appear too unfocussed or too broad. If in doubt, split your GEP into several well-focussed ones.
  2. The GEP champion then emails the GEP editor at <opengrads-devel@sf.net> with a proposed title and a rough, but fleshed out, draft of the GEP. This draft must be written in GEP style as described below.
  3. If the GEP editor approves, (s)he will assign the GEP a number, label it as Standards Track, Informational, or Process, give it status "Draft", and create and check-in the initial draft of the GEP. The GEP editor will not unreasonably deny a GEP. Reasons for denying GEP status include duplication of effort, being technically unsound, not providing proper motivation or addressing backwards compatibility, or not in keeping with the OpenGrADS philosophy.
  4. The author of the GEP is then responsible for posting the GEP to the community forums, and marshaling community support for it. As updates are necessary, the GEP author can revise the GEP on the wiki, or can email new GEP versions to the GEP editor for committing.
  5. Standards Track GEPs consist of two parts, a design document and a reference implementation. The GEP should be reviewed and accepted before a reference implementation is begun, unless a reference implementation will aid people in studying the GEP. Standards Track GEPs must include an implementation -- in the form of code, a patch, or a URL to same -- before it can be considered Final.
  6. GEP authors are responsible for collecting community feedback on a GEP before submitting it for review. However, wherever possible, long open-ended discussions on public mailing lists should be avoided.
  7. Once the authors have completed a GEP, they must inform the GEP editor that it is ready for review. GEPs are reviewed by the OpenGrADS development team, who may accept or reject a GEP or send it back to the author(s) for revision.
  8. For a GEP to be accepted it must meet certain minimum criteria. It must be a clear and complete description of the proposed enhancement. The enhancement must represent a net improvement. The proposed implementation, if applicable, must be solid and must not complicate the system unduly.
  9. Once a GEP has been accepted, the reference implementation must be completed. When the reference implementation is complete and accepted, the status will be changed to "Final".
  10. A GEP can also be assigned status "Deferred". The GEP author or editor can assign the GEP this status when no progress is being made on the GEP. Once a GEP is deferred, the GEP editor can re-assign it to draft status.
  11. A GEP can also be "Rejected". Perhaps after all is said and done it was not a good idea. It is still important to have a record of this fact.
  12. GEPs can also be replaced by a different GEP, rendering the original obsolete. This is intended for Informational GEPs, where version 2 of an API can replace version 1.

What belongs in a successful GEP?

Each GEP should have the following parts:

  1. Preamble -- headers containing meta-data about the GEP, including the GEP number, a short descriptive title (limited to a maximum of 44 characters), the names, and optionally the contact info for each author, etc.
  2. Abstract -- a short (~200 word) description of the technical issue being addressed.
  3. Copyright/public domain -- Each GEP must either be explicitly labelled as placed in the public domain (see this GEP as an example) or licensed under the Open Publication License.
  4. Specification -- The technical specification should describe the syntax and semantics of any new feature. The specification should be detailed enough to allow competing, interoperable implementations for any of the current OpenGrADS platforms.
  5. Motivation -- The motivation is critical for GEPs that want to change the OpenGrADS software. It should clearly explain why the existing system is inadequate to address the problem that the GEP solves. GEP submissions without sufficient motivation may be rejected outright.
  6. Rationale -- The rationale fleshes out the specification by describing what motivated the design and why particular design decisions were made. It should describe alternate designs that were considered and related work, e.g. how the feature is supported in other packages. The rationale should provide evidence of consensus within the community and discuss important objections or concerns raised during discussion.
  7. Backwards Compatibility -- All GEPs that introduce backwards incompatibilities must include a section describing these incompatibilities and their severity. The GEP must explain how the author proposes to deal with these incompatibilities. GEP submissions without a sufficient backwards compatibility treatise may be rejected outright.
  8. Reference Implementation -- The reference implementation must be completed before any GEP is given status "Final", but it need not be completed before the GEP is accepted. It is better to finish the specification and rationale first and reach consensus on it before writing code.

The final implementation must include test code and documentation appropriate for either the OpenGrADS language reference or the standard library reference.

GEP Formats and Templates

GEPs are gnerally written using MediaWiki syntax. However, GEPs can also be written in ReStructuredText and then converted to MediaWiki format using utilities such as wikir.

GEP Header Preamble

Each GEP must begin with a header preamble. The headers must appear in the following order. Headers marked with "*" are optional and are described below. All other headers are required.

  GEP: <gep number>
  Title: <gep title>
  Version: <version string>
  Last-Modified: <date string>
  Author: <list of authors' real names and optionally, email addrs>
  Status: <Draft | Active | Accepted | Deferred | Rejected |
           Withdrawn | Final | Replaced>
  Type: <Standards Track | Informational | Process>
* Requires: <gep numbers>
  Created: <date created on, in dd-mmm-yyyy format>
* OpenGrADS-Version: <version number>
* Replaces: <gep number>
* Replaced-By: <gep number>
  • The Author header lists the names, and optionally the email addresses of all the authors/owners of the GEP. The format of the Author header value must be Random J. User <address@dom.ain> if the email address is included, and just Random J. User if the address is not given. If there are multiple authors, each should be on a separate line.
  • The Type header specifies the type of GEP: Standards Track, Informational, or Process.
  • The Created header records the date that the GEP was assigned a number.
  • Standards Track GEPs must have a OpenGrADS-Version header which indicates the version of OpenGrADS that the feature will be released with. Informational and Process GEPs do not need an OpenGrADS-Version header.
  • GEPs may have a Requires header, indicating the GEP numbers that this GEP depends on.
  • GEPs may also have a Replaced-By header indicating that a GEP has been rendered obsolete by a later document; the value is the number of the GEP that replaces the current document. The newer GEP must have a Replaces header containing the number of the GEP that it rendered obsolete.

Reporting GEP Bugs, or Submitting GEP Updates

How you report a bug, or submit a GEP update depends on several factors, such as the maturity of the GEP, the preferences of the GEP author, and the nature of your comments. For the early draft stages of the GEP, it's probably best to send your comments and changes directly to the GEP author. For more mature, or finished GEPs you may want to make the corrections directly on the OpenGrADS wiki, first discussing it with the author.

When in doubt about where to send your changes, please check first with the GEP author and/or GEP editor.

Transferring GEP Ownership

It occasionally becomes necessary to transfer ownership of GEPs to a new champion. In general, we'd like to retain the original author as a co-author of the transferred GEP, but that's really up to the original author. A good reason to transfer ownership is because the original author no longer has the time or interest in updating it or following through with the GEP process, or has fallen off the face of the 'net (i.e. is unreachable or not responding to email). A bad reason to transfer ownership is because you don't agree with the direction of the GEP. We try to build consensus around a GEP, but if that's not possible, you can always submit a competing GEP.

If you are interested in assuming ownership of a GEP, send a message asking to take over, addressed to both the original author and the GEP editor. If the original author doesn't respond to email in a timely manner, the GEP editor will make a unilateral decision (it's not like such decisions can't be reversed :).

GEP Editor Responsibilities & Workflow

A GEP editor must subscribe to the <opengrads-devel@lists.sf.net> list. For each new GEP that comes in an editor does the following:

  • Read the GEP to check if it is ready: sound and complete. The ideas must make technical sense, even if they don't seem likely to be accepted.
  • The title should accurately describe the content.
  • Edit the GEP for language (spelling, grammar, sentence structure, etc.), markup, code style.
  • If the GEP isn't ready, the editor will send it back to the author for revision, with specific instructions.
  • Once the GEP is ready for the wiki, the GEP editor will:
    • Assign a GEP number (almost always just the next available number, but sometimes it's a special/joke number, like 666 or 3141).
    • List the GEP in GEP 0 (in two places: the categorized list, and the numeric list).

Updates to existing GEPs also come in to <opengrads-devel@lists.sf.net>. GEP authors may not have wiki access yet, so we do the commits for them. The editors don't pass judgement on GEPs. We merely do the administrative & editorial part.

Copyright

This document, which borrows heavily from PEP-001, has been placed in the public domain.