[apps-discuss] Review of: draft-sheffer-running-code

Dave Crocker <dcrocker@gmail.com> Wed, 24 April 2013 13:38 UTC

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I have been selected as the Applications Area Review Team reviewer for 
this draft (for background on apps-review, please see 

Please resolve these comments along with any other Last Call comments 
you may receive. Please wait for direction from your document shepherd 
or AD before posting a new version of the draft.


Title:    Improving Awareness of Running Code: the Implementation Status 

I-D:      draft-sheffer-running-code-04

Reviewer:     D. Crocker
Review Date:  24 April 2013


Given an organizational motto of "Rough consensus and running code", 
implementation experience has a value built into the IETF's DNA.  
However formal IETF reliance on running code for specifications has been 
minimal, with its only universal occurrence being in consideration of 
advanced standards status; it is notably /not/ an organizational 
requirement for entry-level Proposed Standard status, if only for the 
very high barrier to publication this imposes on document versions that 
were intended to be preliminary.  The current draft proposes an 
experiment to optionally include documentation of implementations as 
part of document development, prior to issuance of a specification as an 

Within the broader perspective of pre- and post-standardization efforts, 
it is quite common to document available implementations of a 
specification.  (As a convenient example, see http://dkim.org/deploy.)  
In effect, the current proposal merely seeks to have a common IETF-based 
means of recording a type of information that industry has already 
frequently formulated.

In their current form, the draft and the proposal seem likely to be 
useful.  However, both could be improved.

The draft includes some language and assertions that would benefit from 
being a bit more carefully written; questions, comments and suggestions 
are in the detailed comments below.

The proposal itself would benefit from directly paying more attention to 
existing industry practice, which is implied by the "alternatives" 
section; that is, that implementation lists already happen and are 
maintained after IETF document processing. The proposal should do a 
better job of integrating this fact into its design.

One approach could be a relatively simple document change, to 
distinguish between specifying the information to be reported, as 
distinct from the means of reporting it -- think of it as payload vs. 
mechanism...  Specify them separately.  Then define both how to 
incorporate the information directly and the form of an external 
citation to it; this would eliminate the document's section on 
'alternatives' and treat the original and alternative methods as equal.


Detailed Comments:

> 1.  Introduction
>     Most IETF participants are familiar with the saying, "rough consensus
>     and running code" [Tao], and can identify with its pragmatic
>     approach.  However, there are many examples of Internet-Drafts
>     containing protocol specification that have gone through to
>     publication as Proposed Standard RFCs without implementation.  Some
>     of them may never get implemented.

The "however" implies that it is wrong or problematic for Proposed to be 
assigned to unimplemented protocols.  It isn't.  I suggest a softer 
tone, while still noting the relevantfact. Something like:

      It is not a requirement of Proposed Standard status to have any 
implementations; by the time of reaching that status, some 
specifications have been implemented and some have not. Indeed, some 
never get implemented.

>     Over time, a variety of policies have been implemented within the
implemented -> applied

>     IETF to consider running code.  In the Routing Area it used to be a
>     requirement that one or more implementations must exist before an
>     Internet-Draft could be published as a Proposed Standard RFC
>     [RFC1264].  That RFC was later obsoleted and the requirement for
>     implementation was lifted, but each working group was given the
>     authority to impose its own implementation requirements [RFC4794] and
>     at least one working group (IDR) continues to require two independent
>     implementations.
>     The hypothesis behind this document is that there are benefits to the
this -> the current

>     IETF standardization process of producing implementations of protocol
>     specifications before publication as RFCs.  These benefits, which
I suspect that that isn't its "hypothesis" at all, since the document 
does nothing to specify or directly affect policies for requiring or 
encouraging implementation.  Perhaps there is a hope that the proposed 
notation about implementations will serve as some sort of encouragement, 
but that's pretty indirect; success or failure of the proposed 
experiment won't validate or invalidate whether there are benefits to 
early implementation.  And providing for a notation convention hardly 
constitutes an 'incentive'.

Rather, I believe the premise of the document is that the community is 
aided by /more widely knowing about/ early implementations.

>     include determining that the specification is comprehensible and that
>     there is sufficient interest to implement, are further discussed in
>     Section 4.
>     This document describes a simple process that allows authors of

process -> mechanism

>     Internet-Drafts to record the status of known implementations, by
>     including an Implementation Status section.  The document defines
>     (quite informally) the contents of this section, to ensure that the
>     relevant information is included.  This will allow reviewers and
>     working groups to assign due consideration to documents that have the
>     benefit of running code, by considering the running code as evidence
>     of valuable experimentation and feedback that has made the
>     implemented protocols more mature.

The above last sentence seems to be the actual claimed value proposition 
for the experiment.

>     This document provides a mechanism to record and publicize the
This sentence seems entirely redundant.

>     existence of running code.  It is up to the individual working groups
>     to use this information as they see fit, but one result might be the
>     preferential treatment of documents resulting in them being processed
>     more rapidly.
I think it won't be the working group that 'uses' the information, but 
rather IETF management and the broader community?

>     The process in this document is offered as an experiment.  Authors of
>     Internet-Drafts are encouraged to consider using the process for
>     their documents, and working groups are invited to think about
>     applying the process to all of their protocol specifications.
>     The scope of the intended experiment is all Internet-Drafts whether

Probably not all I-Ds, since they do not all contain implementable 

> Sheffer & Farrel        Expires October 14, 2013                [Page 3]
> Internet-Draft                Running Code                    April 2013
>     produced within IETF working groups, outside working groups but

What I-Ds are produced by "outside working groups"?  I can't tell who 
this refers to.It's probably just as well to remove the attempted case 
analysis for groups and just say that the scope is all specifications 
issued as I-Ds.

>     intended for IETF consensus, or for publication on the Independent
>     Stream.  However, it is expected that most benefit from the

that most benefit from the experiment will
the greatest benefit in the experiment will

>     experiment will be seen with Standards Track documents developed
>     within working groups.

Here's my guess:

1. Those offering comments or making decisions about the status of 
document will be aided by this added information.

2. Those deciding about whether to write code or deploy it will be aided.

I think the latter is likely to be the greater benefit.

>     The authors of this document intend to collate experiences with this
>     experiment and to report them to the community.
> 2.  The "Implementation Status" Section
>     Each Internet-Draft may contain a section entitled "Implementation
>     Status".  This section, if it appears, should be located just before
>     the "Security Considerations" section and contain, for each existing
>     implementation:
>     o  The implementation's name and/or a link to a web page describing
>        the implementation.
>     o  A brief general description.
>     o  The implementation's level of maturity: research, prototype,
>        alpha, beta, production, widely used etc.
>     o  Coverage: which parts of the protocol specification are
>        implemented and which versions of the Internet-Draft were
>        implemented.
>     o  Licensing: the terms under which the implementation can be used.
>        For example: proprietary, royalty licensing, freely distributable
>        with acknowledgement (BSD style), freely distributable with
>        requirement to redistribute source (GPL style), other (specify).
>     o  Contact information: ideally a person's name and email address,
>        but possibly just a URL or mailing list.
List the organization that did the implementation and contact 
information for the proper place in the organization.

>     In addition, this section can contain information about the
>     interoperability of any or all of the implementations.
>     Since this information is necessarily time-dependent, it is
>     inappropriate for inclusion in a published RFC.  The authors should

Way to bury the lead.  This stuff won't be in the published document?  
It's only for pre-publication?

>     include a note to the RFC Editor requesting that the section be
>     removed before publication.
> 2.1.  Introductory Text
>     The following boilerplate text is proposed to head the Implementation
>     Status section:
> Sheffer & Farrel        Expires October 14, 2013                [Page 4]
> Internet-Draft                Running Code                    April 2013
>        This section records the status of known implementations of the
>        protocol defined by this specification at the time of posting of
>        this Internet-Draft, and is based on a proposal described in [RFC
>        Editor: replace by a reference to this document].  According to
>        [RFC Editor: replace by a reference to this document], "this will
>        allow reviewers and working groups to assign due consideration to
>        documents that have the benefit of running code, by considering
>        the running code as evidence of valuable experimentation and
>        feedback that has made the implemented protocols more mature.  It
>        is up to the individual working groups to use this information as
>        they see fit".
>     Authors are requested to add a note to the RFC Editor at the top of
>     this section, advising the Editor to remove the entire section before
>     publication, as well as the reference to [RFC Editor: replace by a
>     reference to this document].
> 3.  Alternative Formats

>     Sometimes it can be advantageous to publish the implementation status
>     separately from the base Internet-Draft, e.g. on the IETF wiki:
>     o  When the Implementation Status section becomes too large to be
>        conveniently managed within the document.
>     o  When a working group decides to have implementors, rather than
>        authors, keep the status of their implementations current.
>     o  When a working group already maintains an active wiki and prefers
>        to use it for this purpose.
>     It is highly desirable for all readers of the Internet-Draft to be
>     made aware of this information.  Initially this can be done by
>     replacing the Implementation Status section's contents with a URL
>     pointing to the wiki.  Later, the IETF Tools may support this
>     functionality, e.g. by including such a link from the HTMLized draft
>     version, similar to the IPR link.
>     If the implementation status is published separately from the I-D,
>     then this information needs to be openly available without requiring
>     authentication, registration or access controls if it is to have any
>     useful effects.
> 4.  Benefits
>     Publishing the information about implementations provides the working
>     group with several benefits:
> Sheffer & Farrel        Expires October 14, 2013                [Page 5]
> Internet-Draft                Running Code                    April 2013
>     o  Participants are motivated to implement protocol proposals, which
>        helps in discovering protocol flaws at an early stage.

The psychological premise seems to be that getting cited in this list 
will somehow serve as an incentive to implementers. I can imagine that 
they'll like being listed, but find it extremely difficult to believe 
that it will affect whether they do the work; not that I think it's a 
deciding factor, but note that the ego value is further reduced by the 
information's being ephemeral, since it it removed prior to RFC publication!

>     o  Other participants can use the software, to evaluate the
>        usefulness of protocol features, its correctness (to some degree)
>        and other properties, such as resilience and scalability.

Efficacy of the spec.

>     o  WG members may choose to perform interoperability testing with
>        known implementations, especially when they are publicly
>        available.

Interoperability of the spec.

>     o  In the case of open source, people may want to study the code to
>        better understand the protocol and its limitations, determine if
>        the implementation matches the protocol specification, and whether
>        the protocol specification has omissions or ambiguities.
Reference implementation as exemplar.

>     o  Working group chairs and ADs may use the information provided to
>        help prioritize the progress of I-Ds in some way.
What does "prioritize the progress" mean?

>     o  Similarly, the information is useful when deciding whether the
>        document should be progressed on a different track (individual
>        submission, Experimental etc.).
Assess spec maturity.  (This seems redundant with the combination of 
Efficacy and Interoperability?)

>     o  And lastly, some protocol features may be hard to understand, and
>        for such features, the mere assurance that they can be implemented
>        is beneficial.
mumble.  Might highlight problems with the spec language. Might 
undermine the spec text by causing code to be used in place of it?

>     We do not specify here whether and to what degree working groups are
>     expected to prefer proposals that have "running code" associated with
>     them, over others that do not.
> 5.  Process Experiment
>     The current proposal is proposed as an experiment.  The inclusion of
>     "Implementation Status" sections in Internet-Drafts is not mandatory,
>     but the authors of this document wish to encourage authors of other
>     Internet-Drafts to try out this simple process to discover whether it
>     is useful.  Working group chairs are invited to suggest this process
>     to document editors in their working groups, and to draw the
>     attention of their working group participants to "Implementation
>     Status" sections where they exist.
>     Following a community discussion, it was concluded that [RFC3933] is
>     not an appropriate framework for this experiment, primarily because
>     no change is required to any existing process.

It defines a document meta-data encoding mechanism. That's not really a 

> 7.  Security Considerations
>     This is a process document and therefore, it does not have a direct
>     effect on the security of any particular IETF protocol.  Better

Better -> However, better