Network Working Group M. Nottingham
Internet-Draft May 23, 2016
Intended status: Informational
Expires: November 24, 2016
Home Documents for HTTP APIs
draft-nottingham-json-home-04
Abstract
This document proposes a "home document" format for non-browser HTTP
clients.
Note to Readers
The issues list for this draft can be found at
https://github.com/mnot/I-D/labels/json-home .
The most recent (often, unpublished) draft is at
https://mnot.github.io/I-D/json-home/ .
Recent changes are listed at https://github.com/mnot/I-D/commits/gh-
pages/json-home .
For information about implementations, see https://github.com/mnot/I-
D/wiki/json-home .
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
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."
This Internet-Draft will expire on November 24, 2016.
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Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Notational Conventions . . . . . . . . . . . . . . . . . 4
2. JSON Home Documents . . . . . . . . . . . . . . . . . . . . . 4
3. Resource Objects . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Resolving Templated Links . . . . . . . . . . . . . . . . 6
4. Resource Hints . . . . . . . . . . . . . . . . . . . . . . . 7
4.1. allow . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.2. formats . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.3. accept-patch . . . . . . . . . . . . . . . . . . . . . . 8
4.4. accept-post . . . . . . . . . . . . . . . . . . . . . . . 8
4.5. accept-ranges . . . . . . . . . . . . . . . . . . . . . . 9
4.6. accept-prefer . . . . . . . . . . . . . . . . . . . . . . 9
4.7. docs . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.8. precondition-req . . . . . . . . . . . . . . . . . . . . 9
4.9. auth-req . . . . . . . . . . . . . . . . . . . . . . . . 10
4.10. status . . . . . . . . . . . . . . . . . . . . . . . . . 10
5. Representation Hints . . . . . . . . . . . . . . . . . . . . 11
6. Creating and Serving Home Documents . . . . . . . . . . . . . 11
6.1. Managing Change in Home Documents . . . . . . . . . . . . 11
6.2. Evolving and Mixing APIs with Home Documents . . . . . . 12
6.3. Documenting APIs that use Home Documents . . . . . . . . 12
7. Consuming Home Documents . . . . . . . . . . . . . . . . . . 12
8. Security Considerations . . . . . . . . . . . . . . . . . . . 13
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
9.1. HTTP Resource Hint Registry . . . . . . . . . . . . . . . 13
9.2. HTTP Representation Hint Registry . . . . . . . . . . . . 13
9.3. Media Type Registration . . . . . . . . . . . . . . . . . 14
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
10.1. Normative References . . . . . . . . . . . . . . . . . . 14
10.2. Informative References . . . . . . . . . . . . . . . . . 14
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 15
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Appendix B. Frequently Asked Questions . . . . . . . . . . . . . 16
B.1. Why not Microformats? . . . . . . . . . . . . . . . . . . 16
B.2. Why doesn't the format allow references or inheritance? . 16
B.3. What about authentication? . . . . . . . . . . . . . . . 16
B.4. What about "Faults" (i.e., errors)? . . . . . . . . . . . 16
B.5. How Do I find the schema for a format? . . . . . . . . . 17
B.6. How do I express complex query arguments? . . . . . . . . 17
Appendix C. Open Issues . . . . . . . . . . . . . . . . . . . . 17
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 18
1. Introduction
There is an emerging preference for non-browser Web applications
(colloquially, "HTTP APIs") to use a link-driven approach to their
interactions to assure loose coupling, thereby enabling extensibility
and API evolution.
This is based upon experience with previous APIs that specified
static URI paths (such as
"http://api.example.com/v1.0/widgets/abc123/properties"), which have
resulted in brittle, tight coupling between clients and servers.
Sometimes, these APIs are documented by a document format like [WADL]
that is used as a design-time description; i.e., the URIs and other
information they describe are "baked into" client implementations.
In contrast, a "follow your nose" API advertises the resources
available to clients using link relations [RFC5988] and the formats
they support using internet media types [RFC6838]. A client can then
decide - at run time - which resources to interact with based upon
its capabilities (as described by link relations), and the server can
safely add new resources and formats without disturbing clients that
are not yet aware of them.
As such, clients need to be able to discover this information quickly
and efficiently use it to interact with the server. Just as with a
human-targeted "home page" for a site, we can create a "home
document" for a HTTP API that describes it to non-browser clients.
Of course, an HTTP API might use any format to do so; however, there
are advantages to having a standard home document format. This
specification suggests one for consideration, using t he JSON format
[RFC7159].
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1.1. Notational Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
2. JSON Home Documents
A JSON Home Document uses the format described in [RFC7159] and has
the media type "application/json-home".
Its content consists of a root object with a "resources" property,
whose member names are link relation types (as defined by [RFC5988]),
and values are Resource Objects, defined below.
For example:
GET / HTTP/1.1
Host: example.org
Accept: application/json-home
HTTP/1.1 200 OK
Content-Type: application/json-home
Cache-Control: max-age=3600
Connection: close
{
"resources": {
"tag:me@example.com,2016:widgets": {
"href": "/widgets/"
},
"tag:me@example.com,2016:widget": {
"href-template": "/widgets/{widget_id}",
"href-vars": {
"widget_id": "http://example.org/param/widget"
},
"hints": {
"allow": ["GET", "PUT", "DELETE", "PATCH"],
"formats": {
"application/json": {}
},
"accept-patch": ["application/json-patch+json"],
"accept-post": ["application/xml"],
"accept-ranges": ["bytes"]
}
}
}
}
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Here, we have a home document that links to a resource, "/widgets/"
with the relation "tag:me@example.com,2016:widgets". It also links
to an unknown number of resources with the relation type
"tag:me@example.com,2016:widget" using a URI Template [RFC6570],
along with a mapping of identifiers to a variable for use in that
template.
It also gives several hints about interacting with the latter
"widget" resources, including the HTTP methods usable with them, the
patch formats they accept, and the fact that they support partial
requests [RFC7233] using the "bytes" range-specifier.
It gives no such hints about the "widgets" resource. This does not
mean that it (for example) doesn't support any HTTP methods; it means
that the client will need to discover this by interacting with the
resource, and/or examining the documentation for its link relation
type.
Effectively, this names a set of behaviors, as described by a
resource object, with a link relation type. This means that several
link relations might apply to a common base URL; e.g.:
{
"resources": {
"tag:me@example.com,2016:search-by-id": {
"href-template": "/search?id={widget_id}",
"href-vars": {
"widget_id": "http://example.org/param/widget_id"
}
},
"tag:me@example.com,2016:search-by-name": {
"href-template": "/search?name={widget_name}",
"href-vars": {
"widget_name": "http://example.org/param/widget_name"
}
}
}
}
Note that the examples above use both tag [RFC4151] and http
[RFC7230] URIs; any URI scheme can be used to identify link relations
and other artefacts in home documents.
3. Resource Objects
A Resource Object links to resources of the defined type using one of
two mechanisms; either a direct link (in which case there is exactly
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one resource of that relation type associated with the API), or a
templated link, in which case there are zero to many such resources.
Direct links are indicated with an "href" property, whose value is a
URI [RFC3986].
Templated links are indicated with an "href-template" property, whose
value is a URI Template [RFC6570]. When "href-template" is present,
the Resource Object MUST have a "href-vars" property; see "Resolving
Templated Links".
Resource Objects MUST have exactly one of the "href" and "href-vars"
properties.
In both forms, the links that "href" and "href-template" refer to are
URI-references [RFC3986] whose base URI is that of the JSON Home
Document itself.
Resource Objects MAY also have a "hints" property, whose value is an
object that uses named Resource Hints (see Section 4) as its
properties.
3.1. Resolving Templated Links
A URI can be derived from a Templated Link by treating the "href-
template" value as a Level 3 URI Template [RFC6570], using the "href-
vars" property to fill the template.
The "href-vars" property, in turn, is an object that acts as a
mapping between variable names available to the template and absolute
URIs that are used as global identifiers for the semantics and syntax
of those variables.
For example, given the following Resource Object:
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"http://example.org/rel/widget": {
"href-template": "/widgets/{widget_id}",
"href-vars": {
"widget_id": "http://example.org/param/widget"
},
"hints": {
"allow": ["GET", "PUT", "DELETE", "PATCH"],
"formats": {
"application/json": {}
},
"accept-patch": ["application/json-patch+json"],
"accept-post": ["application/xml"],
"accept-ranges": ["bytes"]
}
}
If you understand that "http://example.org/param/widget" is an
numeric identifier for a widget, you can then find the resource
corresponding to widget number 12345 at "http://example.org/
widgets/12345" (assuming that the Home Document is located at
"http://example.org/").
4. Resource Hints
Resource hints allow clients to find relevant information about
interacting with a resource beforehand, as a means of optimizing
communications, as well as advertising available behaviors (e.g., to
aid in laying out a user interface for consuming the API).
Hints are just that - they are not a "contract", and are to only be
taken as advisory. The runtime behavior of the resource always
overrides hinted information.
For example, a resource might hint that the PUT method is allowed on
all "widget" resources. This means that generally, the user has the
ability to PUT to a particular resource, but a specific resource
might reject a PUT based upon access control or other considerations.
More fine-grained information might be gathered by interacting with
the resource (e.g., via a GET), or by another resource "containing"
it (such as a "widgets" collection) or describing it (e.g., one
linked to it with a "describedby" link relation).
This specification defines a set of common hints, based upon
information that's discoverable by directly interacting with
resources. See Section 9.1 for information on defining new hints.
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4.1. allow
o Resource Hint Name: allow
o Description: Hints the HTTP methods that the current client will
be able to use to interact with the resource; equivalent to the
Allow HTTP response header.
o Specification: [this document]
Content MUST be an array of strings, containing HTTP methods.
4.2. formats
o Resource Hint Name: formats
o Description: Hints the representation types that the resource
produces and consumes, using the GET and PUT methods respectively,
subject to the 'allow' hint.
o Specification: [this document]
Content MUST be an object, whose keys are media types, and values are
objects containing Representation Hints (see Section 5).
4.3. accept-patch
o Resource Hint Name: accept-patch
o Description: Hints the PATCH [RFC5789] request formats accepted by
the resource for this client; equivalent to the Accept-Patch HTTP
response header.
o Specification: [this document]
Content MUST be an array of strings, containing media types.
When this hint is present, "PATCH" SHOULD be listed in the "allow"
hint.
4.4. accept-post
o Resource Hint Name: accept-post
o Description: Hints the POST request formats accepted by the
resource for this client.
o Specification: [this document]
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Content MUST be an array of strings, containing media types.
When this hint is present, "POST" SHOULD be listed in the "allow"
hint.
4.5. accept-ranges
o Resource Hint Name: accept-ranges
o Description: Hints the range-specifiers available to the client
for this resource; equivalent to the Accept-Ranges HTTP response
header [RFC7233].
o Specification: [this document]
Content MUST be an array of strings, containing HTTP range-
specifiers.
4.6. accept-prefer
o Resource Hint Name: accept-prefer
o Description: Hints the preferences [RFC7240] supported by the
resource. Note that, as per that specifications, a preference can
be ignored by the server.
o Specification: [this document]
Content MUST be an array of strings, contain preferences.
4.7. docs
o Resource Hint Name: docs
o Description: Hints the location for human-readable documentation
for the relation type of the resource.
o Specification: [this document]
Content MUST be a string containing an absolute-URI [RFC3986]
referring to documentation that SHOULD be in HTML format.
4.8. precondition-req
o Resource Hint Name: precondition-req
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o Description: Hints that the resource requires state-changing
requests (e.g., PUT, PATCH) to include a precondition, as per
[RFC7232], to avoid conflicts due to concurrent updates.
o Specification: [this document]
Content MUST be an array of strings, with possible values "etag" and
"last-modified" indicating type of precondition expected.
4.9. auth-req
o Resource Hint Name: auth-req
o Description: Hints that the resource requires authentication using
the HTTP Authentication Framework [RFC7235].
o Specification: [this document]
Content MUST be an array of objects, each with a "scheme" property
containing a string that corresponds to a HTTP authentication scheme,
and optionally a "realms" property containing an array of zero to
many strings that identify protection spaces that the resource is a
member of.
For example, a Resource Object might contain the following hint:
{
"auth-req": [
{
"scheme": "Basic",
"realms": ["private"]
}
]
}
4.10. status
o Resource Hint Name: status
o Description: Hints the status of the resource.
o Specification: [this document]
Content MUST be a string; possible values are:
o "deprecated" - indicates that use of the resource is not
recommended, but it is still available.
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o "gone" - indicates that the resource is no longer available; i.e.,
it will return a 410 Gone HTTP status code if accessed.
5. Representation Hints
TBD
6. Creating and Serving Home Documents
When making a home document available, there are a few things to keep
in mind:
o A home document is best located at a memorable URI, because its
URI will effectively become the URI for the API itself to clients.
o Home documents can be personalized, just as "normal" home pages
can. For example, you might advertise different URIs, and/or
different kinds of link relations, depending on the client's
identity.
o Home documents SHOULD be assigned a freshness lifetime (e.g.,
"Cache-Control: max-age=3600") so that clients can cache them, to
avoid having to fetch it every time the client interacts with the
service.
o Custom link relation types, as well as the URIs for variables,
should lead to documentation for those constructs.
6.1. Managing Change in Home Documents
The URIs used in home documents MAY change over time. However,
changing them can cause issues for clients that are relying on cached
home documents containing old links.
To mitigate the impact of such changes, servers SHOULD consider:
o Reducing the freshness lifetime of home documents before a link
change, so that clients are less likely to refer to an "old"
document.
o Regarding the "old" and "new" URIs as equally valid references for
an "overlap" period.
o After that period, handling requests for the "old" URIs
appropriately; e.g., with a 404 Not Found, or by redirecting the
client to the new URI.
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6.2. Evolving and Mixing APIs with Home Documents
Using home documents affords the opportunity to change the "shape" of
the API over time, without breaking old clients.
This includes introducing new functions alongside the old ones - by
adding new link relation types with corresponding resource objects -
as well as adding new template variables, media types, and so on.
It's important to realise that a home document can serve more than
one "API" at a time; by listing all relevant relation types, it can
effectively "mix" different APIs, allowing clients to work with
different resources as they see fit.
6.3. Documenting APIs that use Home Documents
Another use case for "static" API description formats like WSDL and
WADL is to generate documentation for the API from them.
An API that uses the home document format correctly won't have a need
to do so, provided that the link relation types and media types it
uses are well-documented already.
7. Consuming Home Documents
Clients might use home documents in a variety of ways.
In the most common case - actually consuming the API - the client
will scan the Resources Object for the link relation(s) that it is
interested in, and then to interact with the resource(s) referred to.
Resource Hints can be used to optimize communication with the client,
as well as to inform as to the permissible actions (e.g., whether PUT
is likely to be supported).
Note that the home document is a "living" document; it does not
represent a "contract", but rather is expected to be inspected before
each interaction. In particular, links from the home document MUST
NOT be assumed to be valid beyond the freshness lifetime of the home
document, as per HTTP's caching model [RFC7234].
As a result, clients SHOULD cache the home document (as per
[RFC7234]), to avoid fetching it before every interaction (which
would otherwise be required).
Likewise, a client encountering a 404 Not Found on a link SHOULD
obtain a fresh copy of the home document, to assure that it is up-to-
date.
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8. Security Considerations
Clients need to exercise care when using hints. For example, a naive
client might send credentials to a server that uses the auth-req
hint, without checking to see if those credentials are appropriate
for that server.
9. IANA Considerations
9.1. HTTP Resource Hint Registry
This specification defines the HTTP Resource Hint Registry. See
Section 4 for a general description of the function of resource
hints.
In particular, resource hints are generic; that is, they are
potentially applicable to any resource, not specific to one
application of HTTP, nor to one particular format. Generally, they
ought to be information that would otherwise be discoverable by
interacting with the resource.
Hint names MUST be composed of the lowercase letters (a-z), digits
(0-9), underscores ("_") and hyphens ("-"), and MUST begin with a
lowercase letter.
Hint content SHOULD be described in terms of JSON [RFC7159]
constructs.
New hints are registered using the Expert Review process described in
[RFC5226] to enforce the criteria above. Requests for registration
of new resource hints are to use the following template:
o Resource Hint Name: [hint name]
o Description: [a short description of the hint's semantics]
o Specification: [reference to specification document]
Initial registrations are enumerated in Section 4.
9.2. HTTP Representation Hint Registry
TBD
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9.3. Media Type Registration
TBD
10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<http://www.rfc-editor.org/info/rfc3986>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
DOI 10.17487/RFC5226, May 2008,
<http://www.rfc-editor.org/info/rfc5226>.
[RFC5988] Nottingham, M., "Web Linking", RFC 5988,
DOI 10.17487/RFC5988, October 2010,
<http://www.rfc-editor.org/info/rfc5988>.
[RFC6570] Gregorio, J., Fielding, R., Hadley, M., Nottingham, M.,
and D. Orchard, "URI Template", RFC 6570,
DOI 10.17487/RFC6570, March 2012,
<http://www.rfc-editor.org/info/rfc6570>.
[RFC7159] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March
2014, <http://www.rfc-editor.org/info/rfc7159>.
[RFC7234] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "Hypertext Transfer Protocol (HTTP/1.1): Caching",
RFC 7234, DOI 10.17487/RFC7234, June 2014,
<http://www.rfc-editor.org/info/rfc7234>.
10.2. Informative References
[MICROFORMATS]
microformats.org, "Microformats", n.d.,
<http://microformats.org/>.
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[RFC4151] Kindberg, T. and S. Hawke, "The 'tag' URI Scheme",
RFC 4151, DOI 10.17487/RFC4151, October 2005,
<http://www.rfc-editor.org/info/rfc4151>.
[RFC5789] Dusseault, L. and J. Snell, "PATCH Method for HTTP",
RFC 5789, DOI 10.17487/RFC5789, March 2010,
<http://www.rfc-editor.org/info/rfc5789>.
[RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type
Specifications and Registration Procedures", BCP 13,
RFC 6838, DOI 10.17487/RFC6838, January 2013,
<http://www.rfc-editor.org/info/rfc6838>.
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing",
RFC 7230, DOI 10.17487/RFC7230, June 2014,
<http://www.rfc-editor.org/info/rfc7230>.
[RFC7232] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Conditional Requests", RFC 7232,
DOI 10.17487/RFC7232, June 2014,
<http://www.rfc-editor.org/info/rfc7232>.
[RFC7233] Fielding, R., Ed., Lafon, Y., Ed., and J. Reschke, Ed.,
"Hypertext Transfer Protocol (HTTP/1.1): Range Requests",
RFC 7233, DOI 10.17487/RFC7233, June 2014,
<http://www.rfc-editor.org/info/rfc7233>.
[RFC7235] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Authentication", RFC 7235,
DOI 10.17487/RFC7235, June 2014,
<http://www.rfc-editor.org/info/rfc7235>.
[RFC7240] Snell, J., "Prefer Header for HTTP", RFC 7240,
DOI 10.17487/RFC7240, June 2014,
<http://www.rfc-editor.org/info/rfc7240>.
[WADL] Hadley, M. and Sun Microsystems, "Web Application
Description Language", n.d.,
<http://www.w3.org/Submission/wadl/>.
Appendix A. Acknowledgements
Thanks to Jan Algermissen, Mike Amundsen, Bill Burke, Sven Dietze,
Graham Klyne, Leif Hedstrom, Joe Hildebrand, Jeni Tennison, Erik
Wilde and Jorge Williams for their suggestions and feedback.
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Appendix B. Frequently Asked Questions
B.1. Why not Microformats?
Browser-centric Web applications use HTML as their representation
format of choice. While it is possible to augment HTML for non-
browser clients (using techniques like Microformats [MICROFORMATS]),
a few issues become evident when doing so:
o HTML has a very forgiving syntax. While this is appropriate for
browsers (especially considering that there are many million HTML
authors in the world), it makes for a less-than-precise language
for machines, resulting in both overhead (parsing and
transmission) as well as lack of precision.
o HTML is presentation-centric, making it tempting to reformat it
from time to time, to improve the "look and feel" of a page.
However, doing so can cause comparatively brittle non-browser
clients to lose their understanding of the content's semantics,
unless very careful controls are in place.
Because of this, it's most practical to define a separate format, and
JSON is easily machine-readable, precise, and has a better chance of
being managed for stability.
B.2. Why doesn't the format allow references or inheritance?
Adding inheritance or references would allow more modularity in the
format and make it more compact, at the cost of considerable
complexity and the associated potential for errors (both in the
specification and by its users).
Since good tools and compression are effective ways to achieve the
same ends, this specification doesn't attempt them.
B.3. What about authentication?
In HTTP, authentication is discoverable by interacting with the
resource (usually, by getting a 401 Unauthorized response status
code, along with one or more challenges). While the home document
could hint it, this isn't yet done, to avoid possible security
complications.
B.4. What about "Faults" (i.e., errors)?
In HTTP, errors are conveyed by HTTP status codes. While this
specification could (and even may) allow enumeration of possible
error conditions, there's a concern that this will encourage
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applications to define many such "faults", leading to tight coupling
between the application and its clients.
B.5. How Do I find the schema for a format?
That isn't addressed by home documents. Ultimately, it's up to the
media type accepted and generated by resources to define and
constrain (or not) their syntax.
B.6. How do I express complex query arguments?
Complex queries - i.e., those that exceed the expressive power of
Link Templates or would require ambiguous properties of a "resources"
object - aren't intended to be defined by a home document. The
appropriate way to do this is with a "form" language, much as HTML
defines.
Note that it is possible to support multiple query syntaxes on the
same base URL, using more than one link relation type; see the
example at the start of the document.
Appendix C. Open Issues
The following is a list of placeholders for open issues.
o top-level object(s)
* contact details
* overall documentation
* release info?
* ToS
* rate limiting (per-resource?)
o Resource Hints
* indicate a POST to 201 Created pattern
* indicate an "action" POST
* outbound links
* forms?
o Representation Hints
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* format profiles
* deprecation
o Defining new top-level and resource object properties - how new
ones are minted, registry, etc.
o Discovery (e.g., conneg, .well-known, etc.)
o LIMITED include function?
Author's Address
Mark Nottingham
Email: mnot@mnot.net
URI: http://www.mnot.net/
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