Network Working Group Brian Pawlowski
Internet-Draft Network Appliance
Scott Bradner
Harvard University
Allison Mankin
USC/ISI
November 2002
Advancement of Application Programming Interface specifications
on the IETF Standards Track
<draft-pawlowski-apitest-01.txt>
1. Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC 2026.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet- Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html
A revised version of this draft document will be submitted to the RFC
editor as a BCP (Best Current Practice) documenting an IESG procedure
for the Internet Community.
Discussion and suggestions for improvement are requested. This
document will expire before August, 2002. Distribution of this draft
is unlimited.
2. Abstract
The Internet Standards Process [RFC2026] requires that all IETF
Standards Track specifications must have "multiple, independent, and
interoperable implementations" before they can be advanced beyond
Proposed Standard status. This document specifies the test which the
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IESG will use to determine if an Application Programming Interface
(API) specification document meets these requirements. It also
discusses the rationale for this process.
3. The Nature of the Problem
The Internet Standards Process [RFC2026] requires that for a IETF
specification to advance beyond the Proposed Standard level, at least
two genetically unrelated implementations must be shown to
interoperate correctly with all features and options. There are two
distinct reasons for this requirement.
The first reason is to verify that the text of the specification is
adequately clear and accurate. This is demonstrated by showing that
multiple implementation efforts have used the specification to
achieved interoperable implementations.
The second reason is to discourage excessive options and "feature
creep". This is accomplished by requiring interoperable
implementation of all features, including options. If an option is
not included in at least two different interoperable implementations,
it is safe to assume that it has not been deemed useful and must be
removed before the specification can advance.
In the case of a protocol specification which specifies the "bits on
the wire" exchanged by executing state machines, the notion of
"interoperability" is reasonably intuitive - the implementations must
successfully "talk to each other", exchanging "bits on the wire",
while exercising all features and options.
In the case of a specification for an application programming
interface (API), a security framework for example [RFC 2744 and
RFC2853] describing language bindings for [RFC2743], exactly what
constitutes "interoperation" is less obvious. This document
specifies how the IESG has decided to judge "API specification
interoperability" in the context of the IETF Standards Process.
For the purposes of this document, APIs define a method of accessing
services for callers in a generic fashion, supportable with a range
of underlying mechanisms and technologies and hence allowing
source-level portability of applications to different environments.
An API specification defines services and primitives at a level
independent of underlying mechanism and programming language
environment, and is to be complemented by other, related
specifications defining specific language bindings and token formats
and protocols in support of the services provided by the API.
The aim is to ensure that the dual goals of specification clarity and
feature evaluation have been met using an interpretation of the
concept of API specification interoperability that strikes a
balance between testing complexity and practicality.
4. On The Nature of API specifications
Compared to "state machine" protocols which focus on procedural
specifications, an API specification describes a method of
constructing and deconstructing data for transmission over-the-wire
using a standard set of routines or programming interfaces such that
interoperability is assured. One example of such an API would be a
way allows a communicating application to authenticate the user
associated with another application, to delegate rights to another
application, and to apply security services such as confidentiality
and integrity on a per-message basis while being sent from one
network location to another - without regard to the specific security
mechanism chosen.
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A central issue is that an API specification does not stand alone; it
forms the access interface to the data underneath it. Without the
data, an API provides structure but no content. Since
implementations of APIs are by their nature standalone and do not
interact with each other, the level of the interoperability called
for in the IETF standards process cannot be simply determined by
seeing that the implementations interact properly.
5. Discussion and Recommended Process
In order to meet their obligations under the IETF Standards Process
the IESG must be convinced that each API specification advanced to
Draft Standard or Internet Standard status is clearly written, that
there are the required multiple interoperable implementations, and
that all options have been implemented. There may be multiple ways
to achieve this goal; this memo documents the way that the IESG will
use to determine if the requirements have been met.
In the context of this memo, APIs are designed to uniformly construct
data for exchange over a data network. An aim of any API definition
should be that it should be specified in a way that can reliably
construct data for transmission and receipt in the face of
heterogeneous end points. Thus exchanging data constructed by an API
should allow reliable interoperable exchange regardless of end
points. In the same way, sequentially running different
implementations of software that construct and deconstruct data
using the API should produce the same results.
Following these assumptions any recommendation for the advancement of
a API specification must be accompanied by an implementation report,
as is the case with all requests for the advancement of IETF
specifications. The implementation report must include reports of
tests performed between sets of points on a network with two or more
implementations of the software. Each API specification suggested
for advancement must have one or more advocates who can make a
convincing argument that the API specification meets the multiple
implementation and feature support requirements of the IETF Standards
Process. The specific way to make the argument is left to the
advocate, but will normally include reports that basic data exchange
testing has been done. The API should be tested with at least two
substantially different data to be exchanged (for example, in the
case of a security API, it should be shown that the API correctly
supports two different security mechanisms).
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The prime concern of the IESG will be that the underlying reasons for
the interoperable implementations are met, i.e. that the text of the
specification is clear and unambiguous, and that features of the
specification which have not garnered support have been removed from
the specification before the specification can be advanced on the
standards track. If the API has options (it is defined as a set of
procedures), all of the options (and procedures) must be tested in
the same way.
An implementation report is required for both the advancement from
Proposed Standard to Draft Standard and from Draft Standard to
Internet Standard. The implementation report for advancement from
Draft Standard to Internet Standard can be an updated version of the
one used for the advancement from Proposed Standard to Draft
Standard.
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The implementation report must include the reasons why the IESG
should believe that there are multiple implementations of the API
specification in question and that the all of the API routines in the
specification to be advanced are supported in more than one
implementation. But note that the prime concern of the IESG will be
that the underlying reasons for the interoperable implementations are
met, i.e., that the text of the specification is clear and
unambiguous, and that features of the specification which have not
garnered support have been removed.
The implementation report will be placed on the IETF web page along
with the other pre-advancement implementation reports and will be
specifically referred to in the IETF Last-Call. As with all such
implementation reports, the determination of adequacy is made by the
IESG upon recommendation by the Area Director(s) of the relevant IETF
Area. This determination of adequacy can be challenged during the
Last-Call period.
6. Security Considerations
Some may view this policy as possibly leading to a reduction in the
level of confidence people can have in API specifications, but
the IESG feels that it will adequately ensure a reasonable evaluation
of the level of clarity and ensure that unused options can be
identified and removed before the advancement of a specification.
Good, clearly written API specifications can be of great assistance
in the deployment of interoperable implementations on the Internet
and likely assist in the reduction of some types of security threats
through standardize data construction.
7. Acknowledgements
The basic format and some of the text for this memo came from
[RFC2438], "Advancement of MIB specifications on the IETF Standards
Track", which provides similar guidance for the advancement of MIBs
and [Bradner] "Advancement of Metrics specifications on the IETF
Standards Track" providing guidance on advancement of metrics.
8. References
[RFC2026] "The Internet Standards Process -- Revision 3", Bradner,
October 1996
[RFC2438] "Advancement of MIB specifications on the IETF Standards
Track", O'Dell, Alvestrand, Wijnen, & Bradner, October 1998
[Bradner] "Advancement of Metrics specifications on the IETF
Standards Track", Bradner, Mankin, Paxson,
draft-bradner-metricstest-00.txt, February 2000
[RFC2743] "Generic Security Service Application Program Interface
Version 2, Update 1", Linn, January 2000
[RFC2744] "Generic Security Service API Version 2 : C-bindings",
Wray, January 2000
[RFC2853] "Generic Security Service API Version 2 : Java Bindings",
Kabat, Upadhyay, June 2000
9. Author's Addresses
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Brian Pawlowski
Network Appliance
495 East Java Drive
Sunnyvale, CA 94089
USA
Email: beepy@netapp.com
Phone: +1-408-822-6796
Scott Bradner
Harvard University
29 Oxford St.
Cambridge MA 02138
Email: sob@harvard.edu
Phone: +1-617-495-3864
Allison Mankin
USC/ISI
4350 N. Fairfax Drive, Suite 620
Arlington VA 22203
Email: mankin@isi.edu
Phone: +1-703-812-3706
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