Network Working Group Paul E. Jones
Internet Draft Gonzalo Salgueiro
Intended status: Standards Track Cisco Systems
Expires: October 9, 2012 Joseph Smarr
Google
April 9, 2012
WebFinger
draft-jones-appsawg-webfinger-03.txt
Abstract
This specification defines the WebFinger protocol. WebFinger may be
used to discover information about people on the Internet, such as a
person's personal profile address, identity service, telephone
number, or preferred avatar. WebFinger may also be used to learn
information about objects on the network, such as the amount of toner
in a printer or the physical location of a server.
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-
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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 October 9, 2012.
Copyright Notice
Copyright (c) 2012 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
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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...................................................2
2. Terminology....................................................3
3. Example Uses of WebFinger......................................3
3.1. Locating a User's Blog....................................3
3.2. Retrieving a Person's Contact Information.................5
3.3. Simplifying the Login Process.............................6
3.4. Retrieving Device Information.............................7
4. WebFinger Protocol.............................................8
4.1. Performing a WebFinger Query..............................8
4.2. The Web Host Metadata "resource" Parameter................9
4.3. The Web Host Metadata "rel" Parameter....................11
5. The "acct" URI................................................12
5.1. Using the "acct" URI.....................................12
5.2. Syntax of "acct" URI.....................................13
6. The "acct" Link Relation......................................13
6.1. Purpose for the "acct" Link Relation.....................13
6.2. Example Message Exchange Using the "acct" Link Relation..14
7. Cross-Origin Resource Sharing (CORS)..........................15
8. Security Considerations.......................................15
9. IANA Considerations...........................................16
9.1. Registration of the "acct" URI scheme name...............16
9.2. Registration of the "acct" Link Relation Type............16
10. Acknowledgments..............................................17
11. References...................................................17
11.1. Normative References....................................17
11.2. Informative References..................................18
Author's Addresses...............................................19
1. Introduction
There is a utility found on UNIX systems called "finger" [14] that
allows a person to access information about another person. The
information being queried might be on a computer anywhere in the
world. The information returned via "finger" is simply a plain text
file that contains unstructured information provided by the queried
user.
WebFinger borrows the concept of the legacy finger protocol, but
introduces a very different approach to sharing information. Rather
than returning a simple unstructured text file, Webfinger uses
structured documents that contain link relations. These link
relations point to information a user or entity on the Internet
wishes to expose. For a person, the kinds of information that might
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be exposed include a personal profile address, identity service,
telephone number, or preferred avatar. WebFinger may also be used to
learn information about objects on the network, such as the amount of
toner in a printer or the physical location of a server.
Information returned via WebFinger might be for direct human
consumption (e.g., another user's phone number) or it might be used
by systems to help carry out some operation (e.g., facilitate logging
into a web site by determining a user's identification service).
2. Terminology
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 RFC 2119 [1].
WebFinger makes heavy use of "Link Relations". Briefly, a Link
Relation is an attribute and value pair used on the Internet wherein
the attribute identifies the type of link to which the associated
value refers. In Hypertext Transfer Protocol (HTTP) [2] and Web
Linking [3], the attribute is a "rel" and the value is an "href".
3. Example Uses of WebFinger
In this section, we describe just a few sample uses for WebFinger and
show what the protocol looks like. This is not an exhaustive list of
possible uses and the entire section should be considered non-
normative. The list of potential use cases is virtually unlimited
since a user can share any kind of machine-consumable information via
WebFinger.
3.1. Locating a User's Blog
Assume you receive an email from Bob and he refers to something he
posted on his blog, but you do not know where Bob's blog is located.
It would be simple to discover the address of Bob's blog if he makes
that information available via WebFinger.
Let's assume your email client discovers that blog automatically for
you. After receiving the message from Bob (bob@example.com), your
email client performs the following steps behind the scenes.
First, it tries to get the host metadata [9] information for the
domain example.com. It does this by issuing the following HTTPS
query to example.com:
GET /.well-known/host-meta HTTP/1.1
Host: example.com
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The server replies with an XRD [8] document:
HTTP/1.1 200 OK
Access-Control-Allow-Origin: *
Content-Type: application/xrd+xml; charset=UTF-8
The client then processes the received XRD in accordance with the Web
Host Metadata [9] procedures. The client will see the LRDD link
relation and issue a query with the user's account URI [5]. (The
Account URI is discussed in Section 4.2.) The query might look like
this:
GET /lrdd/?uri=acct%3Abob%40example.com HTTP/1.1
Host: example.com
The server might then respond with a message like this:
HTTP/1.1 200 OK
Access-Control-Allow-Origin: *
Content-Type: application/xrd+xml; charset=UTF-8
2012-03-13T20:56:11Zacct:bob@example.com
The email client might take note of the "blog" link relation in the
above XRD document that refers to Bob's blog. This URL would then be
presented to you so that you could then visit his blog.
The email client might also note that Bob has published an avatar
link relation and use that picture to represent Bob inside the email
client.
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3.2. Retrieving a Person's Contact Information
Assume you have Alice in your address book, but her phone number
appears to be invalid. You could use WebFinger to find her current
phone number and update your address book.
Let's assume you have a web-based address book that you wish to
update. When you instruct the address book to pull Alice's current
contact information, the address book might issue a query like this
to get host metadata information for example.com:
GET /.well-known/host-meta.json HTTP/1.1
Host: example.com
Note the address book is looking for a JSON [4] representation,
whereas we used XML in the previous example.
The server might reply with something like this:
HTTP/1.1 200 OK
Access-Control-Allow-Origin: *
Content-Type: application/json; charset=UTF-8
{
"links" :
[
{
"rel" : "lrdd",
"type" : "application/json",
"template" :
"https://example.com/lrdd/?format=json&uri={uri}"
}
]
}
The client processes the response as described in RFC 6415 [9]. It
will process the LRDD link relation using Alice's account URI by
issuing this query:
GET /lrdd/?format=json&uri=acct%3Aalice%40example.com HTTP/1.1
Host: example.com
The server might return a response like this:
HTTP/1.1 200 OK
Access-Control-Allow-Origin: *
Content-Type: application/json; charset=UTF-8
{
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"expires" : "2012-03-13T20:56:11Z",
"subject" : "acct:alice@example.com",
"links" :
[
{
"rel" : "http://webfinger.net/rel/avatar",
"href" : "http://example.com/~alice/alice.jpg"
},
{
"rel" : "vcard",
"href" : "http://example.com/~alice/alice.vcf"
}
]
}
With this response, the address book might see the vcard [16] link
relation and use that file to offer you updated contact information.
3.3. Simplifying the Login Process
OpenID (http://www.openid.net) is great for allowing users to log
into a web site, though one criticism is that it is challenging for
users to remember the URI they are assigned. WebFinger can help
address this issue by allowing users to use user@domain-style
addresses. Using a user's account URI, a web site can perform a
query to discover the associated OpenID identifier for a user.
Let's assume Carol is trying to use OpenID to log into a blog. The
blog server might issue the following query to get the host metadata
information:
GET /.well-known/host-meta.json HTTP/1.1
Host: example.com
The response that comes back is similar to the previous example:
HTTP/1.1 200 OK
Access-Control-Allow-Origin: *
Content-Type: application/json; charset=UTF-8
{
"expires" : "2012-03-13T20:56:11Z",
"links" :
[
{
"rel" : "lrdd",
"type" : "application/json",
"template" :
"https://example.com/lrdd/?format=json&uri={uri}"
}
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]
}
The blog server processes the response as described in RFC 6415. It
will process the LRDD link relation using Carol's account URI by
issuing this query:
GET /lrdd/?format=json&uri=acct%3Acarol%40example.com HTTP/1.1
The server might return a response like this:
HTTP/1.1 200 OK
Access-Control-Allow-Origin: *
Content-Type: application/json; charset=UTF-8
{
"subject" : "acct:carol@example.com",
"links" :
[
{
"rel" : "http://webfinger.net/rel/avatar",
"href" : "http://example.com/~alice/alice.jpg"
},
{
"rel" : "http://specs.openid.net/auth/2.0/provider",
"href" : "https://openid.example.com/carol"
}
]
}
At this point, the blog server knows that Carol's OpenID identifier
is https://openid.example.com/carol and could then proceed with the
login process as usual.
3.4. Retrieving Device Information
While the examples thus far have been focused on information about
humans, WebFinger does not limit queries to only those that use the
account URI scheme. Let's suppose there are devices on the network
like printers and you would like to check the current toner level for
a particular printer identified via the URI like
device:p1.example.com. While the "device" URI scheme is not
presently specified, we use it here for illustrative purposes.
Following the procedures similar to those above, a query may be
issued to get link relations specific to this URI like this:
GET /lrdd/?format=json&uri=device%3Ap1.example.com HTTP/1.1
Host: example.com
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The link relations that are returned may be quite different than
those for human users. Perhaps we may see a response like this:
HTTP/1.1 200 OK
Access-Control-Allow-Origin: *
Content-Type: application/json; charset=UTF-8
{
"subject" : "device:p1.example.com",
"links" :
[
{
"rel" : "tipsi",
"href" : "http://192.168.1.5/npap/"
}
]
}
While this example is entirely fictitious, you can imagine that
perhaps the Transport Independent, Printer/System Interface [18] may
be enhanced with a web interface that allows a device that
understands the TIP/SI web interface specification to query the
printer for toner levels.
4. WebFinger Protocol
WebFinger does not actually introduce a new protocol, per se.
Rather, it builds upon the existing Web Host Metadata [9]
specification and leverages the Cross-Origin Resource Sharing (CORS)
[7] specification.
4.1. Performing a WebFinger Query
The first step a client must perform in executing a WebFinger query
is to query for the host metadata using HTTPS or HTTP. The
procedures are defined in the Web Host Metadata [9] specification.
WebFinger clients MUST locate the LRDD link relation, if present, and
perform a query for that link relation, if present. All other link
templates found must be processed to form a complete resource
descriptor. The processing rules in Section 4.2 of RFC 6415 MUST be
followed.
WebFinger servers MUST accept requests for both XRD [8] and JRD [9]
documents. The default representation returned by the server MUST be
an XRD document, but a JRD document MUST be returned if the client
explicitly requests it by using /.well-known/host-meta.json or
includes an Accept header in the HTTP request with a type of
"application/json" [4].
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If the client requests a JRD document when querying for host
metadata, the WebFinger server can assume that the client will want a
JRD documents when querying the LRDD resource. As such, when the
WebFinger server returns a JRD document containing host metadata it
should include a URI for an LRDD resource that can return a JRD
document and MAY include a URI for an LRDD resource that will return
an XRD document.
If the client queries the LRDD resource and provides a URI for which
the server has no information, the server MUST return a 404 status
code. Likewise, any query to a URI in the resource descriptor that
is unknown to the server MUST result in the server returning a 404
status code.
WebFinger servers MAY include cache validators in a response to
enable conditional requests by clients and/or expiration times as per
RFC 2616 section 13.
4.2. The Web Host Metadata "resource" Parameter
In addition to the normal processing logic for processing host
metadata information, WebFinger defines the "resource" parameter for
querying for host metadata and returning all of the link relations
from LRDD and other resource-specific link templates in a single
query. This resource essentially pushes the work to the server to
form a complete resource descriptor for the specified resource.
Note that support for the "resource" parameter is optional, but
strongly RECOMMENDED for improved performance. If a server does not
implement the "resource" parameter, then the server's host metadata
processing logic remains unchanged from RFC 6415.
To utilize the host-meta "resource" parameter, a WebFinger client
issues a request to /.well-known/host-meta or /.well-known/host-
meta.json as usual, but then appends a "resource" parameter as shown
in this example:
GET /.well-known/host-meta.json?resource=\
acct%3Abob%40example.com HTTP/1.1
Host: example.com
Note that the "\" character shown above is to indicate that the line
breaks at this point and continues on the next line. This was shown
only to avoid line wrapping in this document and is not a part of the
HTTP protocol.
When processing this request, the WebFinger server MUST
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* Return a 404 status code if the URI provided in the resource
parameter is unknown to the server; and
* Set the "Subject" returned in the response to the value of the
"resource" parameter if the URI provided in the resource
parameter is known to the server
The WebFinger client can verify support for the "resource" parameter
by checking the value of the Subject returned in the response. If
the Subject matches the value of the "resource" parameter, then the
"resource" parameter is supported by the server.
For illustrative purposes, the following is an example usage of the
"resource" parameter that aligns with the example in Section 1.1.1 of
RFC 6415. The WebFinger client would issue this request:
GET /.well-known/host-meta.json?resource=\
http%3A%2F%2Fexample.com%2Fxy HTTP/1.1
Host: example.com
The WebFinger server would reply with this response:
HTTP/1.1 200 OK
Access-Control-Allow-Origin: *
Content-Type: application/json; charset=UTF-8
{
"subject" : "http://example.com/xy",
"properties" :
{
"http://spec.example.net/color" : "red"
},
"links" :
[
{
"rel" : "hub",
"href" : "http://example.com/hub"
},
{
"rel" : "hub",
"href" : "http://example.com/another/hub"
},
{
"rel" : "author",
"href" : "http://example.com/john"
},
{
"rel" : "author",
"template" : "http://example.com/author?\
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q=http%3A%2F%2Fexample.com%2Fxy"
}
]
}
4.3. The Web Host Metadata "rel" Parameter
WebFinger also defines the "rel" parameter for use when querying for
host metadata. It is used to return a subset of the information that
would otherwise be returned without the "rel" parameter. When the
"rel" parameter is used, only the link relations that match the
space-separated list of link relations provided via "rel" are
included in the list of links returned in resource descriptor. All
other information normally present in a resource descriptor is
present in the resource descriptor, even when "rel" is employed.
The purpose of the "rel" parameter is to return a subset of
resource's link relations. It is not intended to reduce the work
required of a server to produce a response. That said, use of the
parameter might reduce processing requirements on either the client
or server, and it might also reduce the bandwidth required to convey
the partial resource descriptor, especially if there are numerous
link relation values to convey for a given resource.
Support for the "rel" parameter is OPTIONAL, but support is
RECOMMENDED for both the host-meta resource and the LRDD resource.
For illustrative purposes, the following is an example usage of the
"rel" parameter that aligns with the example in Section 1.1.1 of RFC
6415. The WebFinger client would issue this request to receive links
that are of the type "hub" and "copyright":
GET /.well-known/host-meta.json?resource=\
http%3A%2F%2Fexample.com%2Fxy&rel=hub%20copyright HTTP/1.1
Host: example.com
The WebFinger server would reply with this response:
HTTP/1.1 200 OK
Access-Control-Allow-Origin: *
Content-Type: application/json; charset=UTF-8
{
"subject" : "http://example.com/xy",
"properties" :
{
"http://spec.example.net/color" : "red"
},
"links" :
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[
{
"rel" : "hub",
"href" : "http://example.com/hub"
},
{
"rel" : "hub",
"href" : "http://example.com/another/hub"
}
]
}
Note that in this example, the "author" links are removed, though all
other content is present. Since there were no "copyright" links,
none are returned.
In the event that a client requests links for link relations that are
not defined for the specified resource, a resource descriptor MUST be
returned, void of any links. When a JRD is returned, the "links"
array MAY be either absent or empty. The server MUST NOT return a
404 status code when a particular link relation specified via "rel"
is not defined for the resource, as a 404 status code is reserved for
indicating that the resource itself (e.g., as indicated via the
"resource" parameter) does not exist.
5. The "acct" URI
The Web Host Metadata specification [9] allows for any kind of
resource to be queried, as does WebFinger. However, a specific type
of resource is needed in order to query information about a human
user.
WebFinger uses the "acct" URI to refer to a human user's account on
the Internet. While other URI scheme MAY be used to query for
information related to a human user, other schemes are not explicitly
defined for that purpose.
5.1. Using the "acct" URI
The "acct" URI takes a familiar form in looking like an email
address. However, the account URI is not an email address and should
not be mistaken for one. Quite often, the account URI minus the
"acct:" scheme prefix may be exactly the same as the user's email
address.
A user MUST NOT be required to enter the "acct" URI scheme name along
with his account identifier into any WebFinger client. Rather, the
WebFinger client MUST accept identifiers that are void of the "acct:"
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portion of the identifier. Composing a properly formatted "acct" URI
is the responsibility of the WebFinger client.
A user MAY provide a fully-specified "acct" URI.
5.2. Syntax of "acct" URI
The "acct" URI syntax is defined here in Augmented Backus-Naur Form
(ABNF) [6] and borrows syntax elements from RFC 3986 [5]:
acctURI = "acct:" userpart "@" domainpart
userpart = 1*( unreserved / pct-encoded )
domainpart = domainlabel 1*( "." domainlabel)
domainlabel = alphanum / alphanum *( alphanum / "-" ) alphanum
alphanum = ALPHA / DIGIT
The "acct" URI scheme allows any character from the Unicode [11]
character set encoded as a UTF-8 [19] string that is then percent-
encoded as necessary into valid ASCII [20]. Characters in the
domainpart must be encoded to support internationalized domain names
(IDNs) [12].
Characters in the userpart or domainpart that are not unreserved must
be percent-encoded when used in a protocol or document that only
supports or requires ASCII. When carried in a document (e.g., XRD or
JRD) or protocol that supports the Unicode character set (e.g., UTF-8
or UTF-16 [21]), the URI strings may appear in the protocol or
document's native encoding without percent-encoding. Such usage of a
URI is commonly referred to as an Internationalized Resource
Identifier (IRI). Conversion between an IRI and URI is described in
Section 3 of RFC 3987 [13].
6. The "acct" Link Relation
6.1. Purpose for the "acct" Link Relation
Users of some services might have an "acct" URI that looks
significantly different from his or her email address, perhaps using
an entirely different domain name. It is also possible for a user
have multiple accounts that a user wants to advertise and that a
WebFinger client may want to query. To address both of these needs,
this specification defines the "acct" link relation.
Since an account may make a reference to one or more different
accounts, WebFinger clients MUST take steps to avoid loops wherein
two accounts, directly or indirectly, refer the client to each other.
There are no limits on the number of "acct" link relations that might
be returned in a WebFinger query.
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An "acct" link relation used within the context of a WebFinger query
for a user's account MUST NOT return "acct" link relations for
another individual.
The "acct" link relation also makes it possible to use the link
relation in HTML documents or in HTTP headers as described in the Web
Linking specification [3]. This would allow, by way of example, for
a user to advertise his or her account identifier in a blog, article,
or other content located on a server that is unrelated to his user
account. Since there may be multiple contributors to an article,
there may be more than one "acct" link relation in an HTML document
or in HTTP headers. It is RECOMMENDED that no more than one "acct"
link relation is advertised per author of a given web page, as a
client may otherwise not understand that the multiple link relations
are for the same person; references to other accounts should be done
from within a user's account, as described in the preceding
paragraphs.
6.2. Example Message Exchange Using the "acct" Link Relation
Consider the following non-normative example.
Suppose Alice receives an email from bob@example.net. While Bob's
email identifier might be in the example.net domain, he holds his
account with an "acct" URI in the example.com domain. His email
provider may provide WebFinger services to enable redirecting Alice
when she queries for acct:bob@example.net.
Suppose Alice's client issues the following request:
GET /.well-known/host-meta.json?resource=\
acct%3Abob%40example.net HTTP/1.1
Host: example.net
The response that Alice's client receives back might be:
HTTP/1.1 200 OK
Access-Control-Allow-Origin: *
Content-Type: application/json; charset=UTF-8
{
"subject" : "acct:bob@example.net",
"links" :
[
{
"rel" : "acct",
"href" : "acct:bob@example.com"
},
{
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"rel" : "acct",
"href" : "acct:bob@example.org"
}
]
}
Alice's WebFinger client could then perform queries against the URIs
acct:bob@example.com and acct:bob@example.org in order to get the
information Alice is seeking.
7. Cross-Origin Resource Sharing (CORS)
WebFinger is most useful when it is accessible without restrictions
on the Internet, and that includes web browsers. Therefore,
WebFinger servers MUST support Cross-Origin Resource Sharing (CORS)
[7]. Specifically, all queries to /.well-known/host-meta, /.well-
known/host-meta.json, and to the LRDD URI must include the following
HTTP header in the response:
Access-Control-Allow-Origin: *
8. Security Considerations
All of the security considerations applicable to Web Host Metadata
[9] and Cross-Origin Resource Sharing [7] are also applicable to this
specification. Of particular importance is the recommended use of
HTTPS to ensure that information is not modified during transit.
Clients should verify that the certificate used on an HTTPS
connection is valid.
When using HTTP to request an XRD document, WebFinger clients SHOULD
verify the XRD document's signature, if present, to ensure that the
XRD document has not been modified. WebFinger servers SHOULD include
a signature for XRD documents.
Service providers and users should be aware that placing information
on the Internet accessible through WebFinger means that any user can
access that information. While WebFinger can be an extremely useful
tool for allowing quick and easy access to one's avatar, blog, or
other personal information, users should understand the risks, too.
If one does not wish to share certain information with the world, do
not allow that information to be accessible through WebFinger.
The aforementioned word of caution is perhaps worth emphasizing again
with respect to dynamic information one might wish to share, such as
the current location of a user. WebFinger can be a powerful tool
used to assemble information about a person all in one place, but
service providers and users should be mindful of the nature of that
information shared and the fact that it might be available for the
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entire world to see. Sharing location information, for example,
would potentially put a person in danger from any individual who
might seek to inflict harm on that person.
The easy access to user information via WebFinger was a design goal
of the protocol, not a limitation. If one wishes to limit access to
information available via WebFinger, such as a WebFinger server for
use inside a corporate network, the network administrator must take
measures necessary to limit access from outside the network.
9. IANA Considerations
RFC Editor: Please replace QQQQ in the following two sub-sections
with a reference to this RFC.
9.1. Registration of the "acct" URI scheme name
This specification requests IANA to register the "acct" URI scheme in
the "Permanent URI Schemes" sub-registry in the "Uniform Resource
Identifier (URI) Schemes" IANA registry [17]. This registration
follows the URI Scheme Registration Template detailed in Section 5.4
of RFC 4395 [15].
URI scheme name: acct
Status: Permanent
URI scheme syntax: see Section 4.1 of RFC QQQQ
URI scheme semantics: see Section 4.1 of RFC QQQQ
Encoding considerations: The "acct" URI scheme allows any character
from the Unicode character set encoded as a UTF-8 string that is
then percent-encoded as necessary to result in an internal
representation in US-ASCII [10]
Applications/protocols that use this URI scheme name: WebFinger
Security considerations: see Section 7 of RFC QQQQ
Contact: Gonzalo Salgueiro
Author/Change controller: IETF
References: See Section 10 of RFC QQQQ
9.2. Registration of the "acct" Link Relation Type
Relation Name: acct
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Description: A link relation that refers to a user's WebFinger
account identifier.
Reference: RFC QQQQ
Notes:
Application Data:
10. Acknowledgments
The authors would like to acknowledge Eran Hammer-Lahav, Blaine Cook,
Brad Fitzpatrick, Laurent-Walter Goix, and Joe Clarke for their
invaluable input.
11. References
11.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[2] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
[3] Nottingham, M., "Web Linking", RFC 5988, October 2010.
[4] Crockford, D., "The application/json Media Type for
JavaScript Object Notation (JSON)", RFC 4627, July 2006.
[5] Berners-Lee, T., Fielding, R., and Masinter, L., "Uniform
Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986,
January 2005.
[6] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008.
[7] Van Kesteren, A., "Cross-Origin Resource Sharing", W3C CORS
http://www.w3.org/TR/cors/, July 2010.
[8] Hammer-Lahav, E. and W. Norris, "Extensible Resource Descriptor
(XRD) Version 1.0", http://docs.oasis-
open.org/xri/xrd/v1.0/xrd-1.0.html.
[9] Hammer-Lahav, E. and Cook, B., "Web Host Metadata", RFC 6415,
October 2011.
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[10] American National Standards Institute, "Coded Character Set -
7-bit American Standard Code for Information Interchange", ANSI
X3.4, 1986.
[11] The Unicode Consortium. The Unicode Standard, Version 6.1.0,
(Mountain View, CA: The Unicode Consortium, 2012. ISBN 978-1-
936213-02-3) http://www.unicode.org/versions/Unicode6.1.0/.
[12] Klensin, J., "Internationalized Domain Names in Applications
(IDNA): Protocol", RFC 5891, August 2010.
[13] Duerst, M., "Internationalized Resource Identifiers (IRIs)",
RFC 3987, January 2005.
11.2. Informative References
[14] Zimmerman, D., "The Finger User Information Protocol", RFC
1288, December 1991.
[15] Hansen, T., Hardie, T., and L. Masinter, "Guidelines and
Registration Procedures for New URI Schemes", BCP 35, RFC 4395,
February 2006.
[16] Perreault, S., "vCard Format Specification", RFC 6350, August
2011.
[17] Internet Assigned Numbers Authority (IANA) Registry, "Uniform
Resource Identifier (URI) Schemes",
.
[18] "Transport Independent, Printer/System Interface", IEEE Std
1284.1-1997, 1997.
[19] Yergeau, F., "UTF-8, a transformation format of ISO 10646", RFC
3629, November 2003.
[20] Information Systems -- Coded Character Sets 7-Bit American
National Standard Code for Information Interchange (7-Bit
ASCII), ANSI X3.4-1986, December 30, 1986.
[21] Hoffman, P., Yergeau, F., "UTF-16, an encoding of ISO 10646",
RFC 2781, February 2000.
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Author's Addresses
Paul E. Jones
Cisco Systems, Inc.
7025 Kit Creek Rd.
Research Triangle Park, NC 27709
USA
Phone: +1 919 476 2048
Email: paulej@packetizer.com
IM: xmpp:paulej@packetizer.com
Gonzalo Salgueiro
Cisco Systems, Inc.
7025 Kit Creek Rd.
Research Triangle Park, NC 27709
USA
Phone: +1 919 392 3266
Email: gsalguei@cisco.com
IM: xmpp:gsalguei@cisco.com
Joseph Smarr
Google
Email: jsmarr@google.com
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Change Log (To Be Deleted Before Publication)
=============================================
-03 Draft
* Changed the name from Webfinger to WebFinger (common usage)
* Added a new paragraph to Section 4.1 to remind readers that WebFinger
benefits from all of the existing HTTP caching functionality
* Added the "rel" parameter to allow filtering the results of a
WebFinger query to include Links of the specified type(s)
* Corrected a reference to an obsoleted RFC
* Removed extraneous text from the terminology section
-02 Draft
* Minor editorial changes
* Added to the XML example to highlight that this element
exists, since some may not be aware
* Changed some of the link relation values, particularly for those that
are not yet standardized
* Added a note about "device:" not being standard
* Overhauled the "acct" link relation text, breaking the normative and
non-normative pieces apart
* Added additional text to the security considerations section related
to dynamic information (e.g., geographic information)
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