draft-ietf-simple-xcap-list-usage-04.txt   draft-ietf-simple-xcap-list-usage-05.txt 
SIMPLE J. Rosenberg SIMPLE J. Rosenberg
Internet-Draft Cisco Systems Internet-Draft Cisco Systems
Expires: April 23, 2005 October 23, 2004 Expires: August 8, 2005 February 7, 2005
Extensible Markup Language (XML) Formats for Representing Resource Extensible Markup Language (XML) Formats for Representing Resource
Lists Lists
draft-ietf-simple-xcap-list-usage-04 draft-ietf-simple-xcap-list-usage-05
Status of this Memo Status of this Memo
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which he or she become aware will be disclosed, in accordance with
RFC 3668. RFC 3668.
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Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2004). All Rights Reserved. Copyright (C) The Internet Society (2005).
Abstract Abstract
In multimedia communications, presence and instant messaging systems, In multimedia communications, presence and instant messaging systems,
there is a need to define Uniform Resource Identifiers (URIs) that there is a need to define Uniform Resource Identifiers (URIs) that
represent services which are associated with a group of users. One represent services which are associated with a group of users. One
example is a resource list service. If a user sends a Session example is a resource list service. If a user sends a Session
Initiation Protocol (SIP) SUBSCRIBE message to the URI representing Initiation Protocol (SIP) SUBSCRIBE message to the URI representing
the resource list service, the server will obtain the state of the the resource list service, the server will obtain the state of the
users in the associated group, and provide it to the sender. To users in the associated group, and provide it to the sender. To
facilitate definition of these services, this specification defines facilitate definition of these services, this specification defines
two Extensible Markup Language (XML) documents. One document two Extensible Markup Language (XML) documents. One document
contains service URIs, along with their service definition and a contains service URIs, along with their service definition and a
reference to the associated group of users. The second document reference to the associated group of users. The second document
contains the user lists which are referenced from the first. Both contains the user lists which are referenced from the first. This
documents can be created and managed with the XML Configuration list of users can be utilized by other applications and services.
Both documents can be created and managed with the XML Configuration
Access Protocol (XCAP). Access Protocol (XCAP).
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Resource Lists Documents . . . . . . . . . . . . . . . . . . . 5 3. Resource Lists Documents . . . . . . . . . . . . . . . . . . . 5
3.1 Structure . . . . . . . . . . . . . . . . . . . . . . . . 5 3.1 Structure . . . . . . . . . . . . . . . . . . . . . . . . 5
3.2 Schema . . . . . . . . . . . . . . . . . . . . . . . . . . 8 3.2 Schema . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.3 Example Document . . . . . . . . . . . . . . . . . . . . . 10 3.3 Example Document . . . . . . . . . . . . . . . . . . . . . 10
3.4 Usage with XCAP . . . . . . . . . . . . . . . . . . . . . 11 3.4 Usage with XCAP . . . . . . . . . . . . . . . . . . . . . 11
3.4.1 Application Unique ID . . . . . . . . . . . . . . . . 11 3.4.1 Application Unique ID . . . . . . . . . . . . . . . . 11
3.4.2 MIME Type . . . . . . . . . . . . . . . . . . . . . . 11 3.4.2 MIME Type . . . . . . . . . . . . . . . . . . . . . . 11
3.4.3 XML Schema . . . . . . . . . . . . . . . . . . . . . . 11 3.4.3 XML Schema . . . . . . . . . . . . . . . . . . . . . . 11
3.4.4 Additional Constraints . . . . . . . . . . . . . . . . 12 3.4.4 Default Namespace . . . . . . . . . . . . . . . . . . 12
3.4.5 Data Semantics . . . . . . . . . . . . . . . . . . . . 12 3.4.5 Additional Constraints . . . . . . . . . . . . . . . . 12
3.4.6 Naming Conventions . . . . . . . . . . . . . . . . . . 12 3.4.6 Data Semantics . . . . . . . . . . . . . . . . . . . . 12
3.4.7 Resource Interdependencies . . . . . . . . . . . . . . 13 3.4.7 Naming Conventions . . . . . . . . . . . . . . . . . . 13
3.4.8 Authorization Policies . . . . . . . . . . . . . . . . 13 3.4.8 Resource Interdependencies . . . . . . . . . . . . . . 13
3.4.9 Authorization Policies . . . . . . . . . . . . . . . . 14
4. RLS Services Documents . . . . . . . . . . . . . . . . . . . . 14 4. RLS Services Documents . . . . . . . . . . . . . . . . . . . . 14
4.1 Structure . . . . . . . . . . . . . . . . . . . . . . . . 14 4.1 Structure . . . . . . . . . . . . . . . . . . . . . . . . 14
4.2 Schema . . . . . . . . . . . . . . . . . . . . . . . . . . 15 4.2 Schema . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.3 Example Document . . . . . . . . . . . . . . . . . . . . . 16 4.3 Example Document . . . . . . . . . . . . . . . . . . . . . 16
4.4 Usage with XCAP . . . . . . . . . . . . . . . . . . . . . 17 4.4 Usage with XCAP . . . . . . . . . . . . . . . . . . . . . 17
4.4.1 Application Unique ID . . . . . . . . . . . . . . . . 17 4.4.1 Application Unique ID . . . . . . . . . . . . . . . . 17
4.4.2 MIME Type . . . . . . . . . . . . . . . . . . . . . . 17 4.4.2 MIME Type . . . . . . . . . . . . . . . . . . . . . . 17
4.4.3 XML Schema . . . . . . . . . . . . . . . . . . . . . . 17 4.4.3 XML Schema . . . . . . . . . . . . . . . . . . . . . . 17
4.4.4 Additional Constraints . . . . . . . . . . . . . . . . 17 4.4.4 Default Namespace . . . . . . . . . . . . . . . . . . 17
4.4.5 Data Semantics . . . . . . . . . . . . . . . . . . . . 19 4.4.5 Additional Constraints . . . . . . . . . . . . . . . . 18
4.4.6 Naming Conventions . . . . . . . . . . . . . . . . . . 19 4.4.6 Data Semantics . . . . . . . . . . . . . . . . . . . . 19
4.4.7 Resource Interdependencies . . . . . . . . . . . . . . 19 4.4.7 Naming Conventions . . . . . . . . . . . . . . . . . . 19
4.4.8 Authorization Policies . . . . . . . . . . . . . . . . 21 4.4.8 Resource Interdependencies . . . . . . . . . . . . . . 19
4.4.9 Authorization Policies . . . . . . . . . . . . . . . . 21
4.5 Usage of an RLS Services Document by an RLS . . . . . . . 22 4.5 Usage of an RLS Services Document by an RLS . . . . . . . 22
5. SIP URI Canonicalization . . . . . . . . . . . . . . . . . . . 24 5. SIP URI Canonicalization . . . . . . . . . . . . . . . . . . . 23
6. Extensibility . . . . . . . . . . . . . . . . . . . . . . . . 25 6. Extensibility . . . . . . . . . . . . . . . . . . . . . . . . 24
7. Security Considerations . . . . . . . . . . . . . . . . . . . 25 7. Security Considerations . . . . . . . . . . . . . . . . . . . 25
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25
8.1 XCAP Application Unique IDs . . . . . . . . . . . . . . . 25 8.1 XCAP Application Unique IDs . . . . . . . . . . . . . . . 25
8.1.1 resource-lists . . . . . . . . . . . . . . . . . . . . 26 8.1.1 resource-lists . . . . . . . . . . . . . . . . . . . . 25
8.1.2 rls-services . . . . . . . . . . . . . . . . . . . . . 26 8.1.2 rls-services . . . . . . . . . . . . . . . . . . . . . 26
8.2 MIME Type Registrations . . . . . . . . . . . . . . . . . 26 8.2 MIME Type Registrations . . . . . . . . . . . . . . . . . 26
8.2.1 application/resource-lists+xml . . . . . . . . . . . . 26 8.2.1 application/resource-lists+xml . . . . . . . . . . . . 26
8.2.2 application/rls-services+xml . . . . . . . . . . . . . 27 8.2.2 application/rls-services+xml . . . . . . . . . . . . . 27
8.3 URN Sub-Namespace Registrations . . . . . . . . . . . . . 28 8.3 URN Sub-Namespace Registrations . . . . . . . . . . . . . 28
8.3.1 urn:ietf:params:xml:ns:resource-lists . . . . . . . . 28 8.3.1 urn:ietf:params:xml:ns:resource-lists . . . . . . . . 28
8.3.2 urn:ietf:params:xml:ns:rls-services . . . . . . . . . 29 8.3.2 urn:ietf:params:xml:ns:rls-services . . . . . . . . . 29
8.4 Schema Registrations . . . . . . . . . . . . . . . . . . . 29 8.4 Schema Registrations . . . . . . . . . . . . . . . . . . . 29
8.4.1 urn:ietf:params:xml:schema:resource-lists . . . . . . 29 8.4.1 urn:ietf:params:xml:schema:resource-lists . . . . . . 29
8.4.2 urn:ietf:params:xml:schema:rls-services . . . . . . . 30 8.4.2 urn:ietf:params:xml:schema:rls-services . . . . . . . 30
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MUST be unique amongst all other "ref" attributes in <entry-ref> MUST be unique amongst all other "ref" attributes in <entry-ref>
elements within the same parent. Uniqueness is determined by case elements within the same parent. Uniqueness is determined by case
sensitive string comparisons. The <entry-ref> element also allows sensitive string comparisons. The <entry-ref> element also allows
attributes from other namespaces, for the purposes of extensibility. attributes from other namespaces, for the purposes of extensibility.
The content of an <entry-ref> element is an optional display name, The content of an <entry-ref> element is an optional display name,
followed by any number of elements from other namespaces, for the followed by any number of elements from other namespaces, for the
purposes of extensibility. The display name is useful for providing purposes of extensibility. The display name is useful for providing
a localized nickname as an alternative to the name defined in the a localized nickname as an alternative to the name defined in the
<entry> to which the <entry-ref> refers. <entry> to which the <entry-ref> refers.
The content of the "ref" attribute is a relative HTTP URL [7]. The content of the "ref" attribute is a relative HTTP URI [7].
Specifically, it MUST be a relative path reference, where the base Specifically, it MUST be a relative path reference, where the base
URL is equal to the XCAP root URI of the document in which the URI is equal to the XCAP root URI of the document in which the
<entry-ref> appears. This relative URL, if resolved into an absolute <entry-ref> appears. This relative URI, if resolved into an absolute
URL according to the procedures in RFC 2396, MUST resolve to an URI according to the procedures in RFC 3986, MUST resolve to an
<entry> element within a resource-lists document. For example, if an <entry> element within a resource-lists document. For example, if an
<entry> element within a specific XCAP root was identified by the <entry> element within a specific XCAP root was identified by the
following HTTP URL: following HTTP URI:
http://xcap.example.com/root/resource-lists/users/bill/ http://xcap.example.com/root/resource-lists/users/bill/
mylist/~~/resource-lists/list%5b@name=%22list1%22%5d/ mylist/~~/resource-lists/list%5b@name=%22list1%22%5d/
entry%5b@uri=%22sip:petri@example.com%22%5d entry%5b@uri=%22sip:petri@example.com%22%5d
If http://xcap.example.com/root is the XCAP root URI, then an If http://xcap.example.com/root is the XCAP root URI, then an
<entry-ref> element pointing to this entry would have the form: <entry-ref> element pointing to this entry would have the form:
<entry-ref ref="resource-lists/users/bill/ <entry-ref ref="resource-lists/users/bill/
mylist/~~/resource-lists/list%5b@name=%22list1%22%5d/ mylist/~~/resource-lists/list%5b@name=%22list1%22%5d/
entry%5b@uri=%22sip:petri@example.com%22%5d"/> entry%5b@uri=%22sip:petri@example.com%22%5d"/>
Note that line folding within the HTTP URL and XML attribute above Note that line folding within the HTTP URI and XML attribute above
are for the purposes of readability only. Also note that, as are for the purposes of readability only. Also note that, as
described in RFC 2396, the relative path URI does not begin with the described in RFC 3986, the relative path URI does not begin with the
"/". Since the relative URL used within the "ref" attribute must be "/". Since the relative URI used within the "ref" attribute must be
a relative path URL, the "/" will never be present as the first a relative path URI, the "/" will never be present as the first
character within the content of a "ref" attribute. Since the content character within the content of a "ref" attribute. Since the content
of the "ref" attribute is a valid HTTP URL, it must be escape encoded of the "ref" attribute is a valid HTTP URI, it must be escape encoded
within the XML document. within the XML document.
The <external> element is similar to the <entry-ref> element. Like The <external> element is similar to the <entry-ref> element. Like
<entry-ref>, it is only meaningful in documents obtained from an XCAP <entry-ref>, it is only meaningful in documents obtained from an XCAP
server. It too is a reference to content stored elsewhere. However, server. It too is a reference to content stored elsewhere. However,
it refers to an entire list, and furthermore, allows that list to be it refers to an entire list, and furthermore, allows that list to be
present on another server. The <external> element has a single present on another server. The <external> element has a single
mandatory attribute, "anchor". The "anchor" attribute MUST be unique mandatory attribute, "anchor", which specifies the external list by
means of an absolute HTTP URI. The "anchor" attribute MUST be unique
amongst all other "anchor" attributes in <external> elements within amongst all other "anchor" attributes in <external> elements within
the same parent. Uniqueness is determined by case sensitive string the same parent. Uniqueness is determined by case sensitive string
comparisons. The <external> element can also contain attributes from comparisons. The <external> element can also contain attributes from
other namespaces, for the purposes of extensibility. The content of other namespaces, for the purposes of extensibility. The content of
an <external> element is an optional <display-name> followed by any an <external> element is an optional <display-name> followed by any
number of elements from another namespace, for the purposes of number of elements from another namespace, for the purposes of
extensibility. The value of the "anchor" attribute MUST be an extensibility. The value of the "anchor" attribute MUST be an
absolute HTTP URL. This URL MUST identify an XCAP resource, and in absolute HTTP URI. This URI MUST identify an XCAP resource, and in
particular, it MUST represent a <list> element within a resource particular, it MUST represent a <list> element within a resource
lists document. The URL MUST be escape coded. lists document. The URI MUST be escape coded.
For both the <entry-ref> and <external> elements, the responsibility For both the <entry-ref> and <external> elements, the responsibility
of resolving their references falls upon the entity that is making of resolving their references falls upon the entity that is making
use of the document. When used in conjunction with XCAP, this means use of the document. When used in conjunction with XCAP, this means
that the burden falls on the XCAP client. If the XCAP client is a PC that the burden falls on the XCAP client. If the XCAP client is a PC
based application using the resource-lists document as a presence based application using the resource-lists document as a presence
list, the references would likely be resolved upon explicit request list, the references would likely be resolved upon explicit request
by the user. They can, of course, be resolved at any time. If the by the user. They can, of course, be resolved at any time. If the
XCAP client is an RLS itself, the references would be resolved when XCAP client is an RLS itself, the references would be resolved when
the RLS receives a SUBSCRIBE request for an RLS service associated the RLS receives a SUBSCRIBE request for an RLS service associated
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<xs:extension base="xs:string"> <xs:extension base="xs:string">
<xs:attribute ref="xml:lang"/> <xs:attribute ref="xml:lang"/>
</xs:extension> </xs:extension>
</xs:simpleContent> </xs:simpleContent>
</xs:complexType> </xs:complexType>
</xs:schema> </xs:schema>
3.3 Example Document 3.3 Example Document
The following is an example of a document compliant to the schema. The following is an example of a document compliant to the schema.
All line feeds within element content is for display purposes only. All line feeds within element content are for display purposes only.
<?xml version="1.0" encoding="UTF-8"?> <?xml version="1.0" encoding="UTF-8"?>
<resource-lists xmlns="urn:ietf:params:xml:ns:resource-lists" <resource-lists xmlns="urn:ietf:params:xml:ns:resource-lists"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<list name="friends"> <list name="friends">
<entry uri="sip:bill@example.com"> <entry uri="sip:bill@example.com">
<display-name>Bill Doe</display-name> <display-name>Bill Doe</display-name>
</entry> </entry>
<entry-ref ref="resource-lists/users/bill/mylist/~~/resource-lists/l <entry-ref ref="resource-lists/users/bill/mylist/~~/resource-lists/l
ist%5b@name=%22list1%22%5d/entry%5b@uri=%22sip:petri@example.com%22%5d"/> ist%5b@name=%22list1%22%5d/entry%5b@uri=%22sip:petri@example.com%22%5d"/>
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3.4.2 MIME Type 3.4.2 MIME Type
The MIME type for this document is "application/resource-lists+xml". The MIME type for this document is "application/resource-lists+xml".
3.4.3 XML Schema 3.4.3 XML Schema
The XML Schema for this document is defined as the sole content of The XML Schema for this document is defined as the sole content of
Section 3.2. Section 3.2.
3.4.4 Additional Constraints 3.4.4 Default Namespace
The default namespace used in expanding URIs is
urn:ietf:params:xml:ns:resource-lists.
3.4.5 Additional Constraints
In addition to the schema, there are constraints on the values In addition to the schema, there are constraints on the values
present in the the "name" attribute of the <list> element, the "uri" present in the the "name" attribute of the <list> element, the "uri"
attribute of the <external> element, the "ref" attribute of the attribute of the <external> element, the "ref" attribute of the
<entry-ref> element and the "anchor" attribute of the <external> <entry-ref> element and the "anchor" attribute of the <external>
element. These constraints are defined in Section 3.1. Some of element. These constraints are defined in Section 3.1. Some of
these constraints are enforced by the XCAP server. Those constraints these constraints are enforced by the XCAP server. Those constraints
are: are:
o The "name" attribute in a <list> element MUST be unique amongst o The "name" attribute in a <list> element MUST be unique amongst
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within the same parent element. Uniqueness is determined by case within the same parent element. Uniqueness is determined by case
sensitive string comparison. The value of the attribute MUST be a sensitive string comparison. The value of the attribute MUST be a
relative path reference. Note that the server is not responsible relative path reference. Note that the server is not responsible
for verifying that the reference resolves to an <entry> element in for verifying that the reference resolves to an <entry> element in
a document within the same XCAP root. a document within the same XCAP root.
o The URI in the "anchor" attribute of the <external> element MUST o The URI in the "anchor" attribute of the <external> element MUST
be unique amongst all other "anchor" attributes of <external> be unique amongst all other "anchor" attributes of <external>
elements within the same parent element. Uniqueness is determined elements within the same parent element. Uniqueness is determined
by case sensitive string comparison. The value of the attribute by case sensitive string comparison. The value of the attribute
MUST be an absolute HTTP URL. Note that the server is not MUST be an absolute HTTP URI. Note that the server is not
responsible for verifying that the URL resolves to a <list> responsible for verifying that the URI resolves to a <list>
element in a document. Indeed, since the URL may reference a element in a document. Indeed, since the URI may reference a
server in another domain, referential integrity cannot be server in another domain, referential integrity cannot be
guaranteed without adding substantial complexity to the system. guaranteed without adding substantial complexity to the system.
3.4.5 Data Semantics 3.4.6 Data Semantics
Semantics for the document content are provided in Section 3.1. Semantics for the document content are provided in Section 3.1.
3.4.6 Naming Conventions 3.4.7 Naming Conventions
Resource lists documents are usually identified as references from Resource lists documents are usually identified as references from
other application usages. For example, an RLS services document other application usages. For example, an RLS services document
contains a reference to the resource list it uses. contains a reference to the resource list it uses.
Frequently, an XCAP client will wish to insert or remove an <entry>, Frequently, an XCAP client will wish to insert or remove an <entry>,
<entry-ref> or <external> element from a document without having a <entry-ref> or <external> element from a document without having a
cached copy of that document. In such a case, the "uri" attribute of cached copy of that document. In such a case, the "uri" attribute of
the <entry> element, the "ref" attribute of the <entry-ref> element the <entry> element, the "ref" attribute of the <entry-ref> element
or the "anchor" attribute of the <external> element is used as an or the "anchor" attribute of the <external> element is used as an
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If the XCAP client cannot determine whether the user intent is to If the XCAP client cannot determine whether the user intent is to
create or replace, the client SHOULD canonicalize the URI before create or replace, the client SHOULD canonicalize the URI before
performing the operation. For a SIP URI (often present in the "uri" performing the operation. For a SIP URI (often present in the "uri"
attribute of the <entry> element), this canonicalization procedure is attribute of the <entry> element), this canonicalization procedure is
defined in Section 5. We expect that the SIP URIs that will be defined in Section 5. We expect that the SIP URIs that will be
placed into resource lists documents will usually be of the form placed into resource lists documents will usually be of the form
sip:user@domain, and possibly include a user parameter. The sip:user@domain, and possibly include a user parameter. The
canonicalization rules work perfectly for these URIs. canonicalization rules work perfectly for these URIs.
For HTTP URLs, a basic canonicalization algorithm is as follows. If For HTTP URIs, a basic canonicalization algorithm is as follows. If
the the port in the URL is equal to the default port (80 for http the the port in the URI is equal to the default port (80 for http
URLs), the port is removed. The hostname is converted to all URIs), the port is removed. The hostname is converted to all
lowercase. Any characters that are escape encoded are un-escaped, lowercase. Any characters that are escape encoded are un-escaped,
and only re-escaped if they cannot be represented within their and only re-escaped if they cannot be represented within their
component of the URL. In other words, if the grammar for a part of component of the URI. In other words, if the grammar for a part of
the URL disallows a certain character, but that character needs to be the URI disallows a certain character, but that character needs to be
present, it is escape coded. present, it is escape coded.
3.4.7 Resource Interdependencies 3.4.8 Resource Interdependencies
There are no resource interdependencies identified by this There are no resource interdependencies identified by this
application usage. application usage.
3.4.8 Authorization Policies 3.4.9 Authorization Policies
This application usage does not modify the default XCAP authorization This application usage does not modify the default XCAP authorization
policy, which is that only a user can read, write or modify their own policy, which is that only a user can read, write or modify their own
documents. A server can allow priveleged users to modify documents documents. A server can allow privileged users to modify documents
that they don't own, but the establishment and indication of such that they don't own, but the establishment and indication of such
policies is outside the scope of this document. It is anticipated policies is outside the scope of this document. It is anticipated
that a future application usage will define which users are allowed that a future application usage will define which users are allowed
to modify a list resource. to modify a list resource.
4. RLS Services Documents 4. RLS Services Documents
4.1 Structure 4.1 Structure
An RLS services document is used to define URIs that represent An RLS services document is used to define URIs that represent
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reason, the <resource-list> element exists as an alternative. It can reason, the <resource-list> element exists as an alternative. It can
reference a <list> element in a resource-lists document. Since the reference a <list> element in a resource-lists document. Since the
list is separated from the service definition, it can be easily list is separated from the service definition, it can be easily
reused by other application usages. reused by other application usages.
The <list> element is of the list type defined by the schema for The <list> element is of the list type defined by the schema for
resource lists. It is discussed in Section 3.1. resource lists. It is discussed in Section 3.1.
The <resource-list> element contains a URI. This element is only The <resource-list> element contains a URI. This element is only
meaningful when the document was obtained through XCAP. The URI MUST meaningful when the document was obtained through XCAP. The URI MUST
be an absolute HTTP URL representing an XCAP element resource. Its be an absolute HTTP URI representing an XCAP element resource. Its
XCAP root MUST be the same as the XCAP root of the RLS services XCAP root MUST be the same as the XCAP root of the RLS services
document. When the RLS services document in present in a user's home document. When the RLS services document is present in a user's home
directory, the HTTP URL MUST exist underneath the same user's home directory, the HTTP URI MUST exist underneath that user's home
directory in the resource-lists application usage. When the RLS directory in the resource-lists application usage. When the RLS
services document is in the global directory, the HTTP URL MUST exist services document is in the global directory, the HTTP URI MUST exist
underneath any user's home directory in the resource-lists underneath any user's home directory in the resource-lists
application usage. In either case, the element referenced by the URI application usage. In either case, the element referenced by the URI
MUST be a <list> element within a resource-lists document. All of MUST be a <list> element within a resource-lists document. All of
these constraints except for the latter one (which is a referential these constraints except for the latter one (which is a referential
integrity constraint) will be enforced by the XCAP server. integrity constraint) will be enforced by the XCAP server.
The <packages> element contains a sequence of <package> elements. The <packages> element contains a sequence of <package> elements.
The content of each <package> element is the name of a SIP event The content of each <package> element is the name of a SIP event
package [14]. The <packages> element may also contain elements from package [14]. The <packages> element may also contain elements from
additional namespaces, for the purposes of extensibility. The additional namespaces, for the purposes of extensibility. The
skipping to change at page 17, line 48 skipping to change at page 17, line 48
4.4.2 MIME Type 4.4.2 MIME Type
The MIME type for this document is "application/rls-services+xml". The MIME type for this document is "application/rls-services+xml".
4.4.3 XML Schema 4.4.3 XML Schema
The XML Schema for this document is defined as the sole content of The XML Schema for this document is defined as the sole content of
Section 4.2. Section 4.2.
4.4.4 Additional Constraints 4.4.4 Default Namespace
The default namespace used in expanding URIs is
urn:ietf:params:xml:ns:rls-services.
4.4.5 Additional Constraints
In addition to the schema, there are constraints on the URIs present In addition to the schema, there are constraints on the URIs present
in the <service> and <resource-list> elements. These constraints are in the <service> and <resource-list> elements. These constraints are
defined in Section 3.1. Some of these constraints are enforced by defined in Section 3.1. Some of these constraints are enforced by
the XCAP server. Those constraints are: the XCAP server. Those constraints are:
o The URI in the "uri" attribute of the <service> element MUST be o The URI in the "uri" attribute of the <service> element MUST be
unique amongst all other URIs in "uri" elements in any <service> unique amongst all other URIs in "uri" elements in any <service>
element in any document on a particular server. This uniqueness element in any document on a particular server. This uniqueness
constraint spans across XCAP roots. Furthermore, the URI MUST NOT constraint spans across XCAP roots. Furthermore, the URI MUST NOT
skipping to change at page 18, line 31 skipping to change at page 18, line 36
tree), the server MUST verify that the XUI in the path is the same tree), the server MUST verify that the XUI in the path is the same
as the XUI in the URI of to the RLS services document. These as the XUI in the URI of to the RLS services document. These
checks are made by examining the URI value, as opposed to checks are made by examining the URI value, as opposed to
de-referencing the URI. The server is not responsible for de-referencing the URI. The server is not responsible for
verifying that the URI actually points to a <list> element within verifying that the URI actually points to a <list> element within
a valid resource lists document. a valid resource lists document.
o In addition, an RLS services document can contain a <list> o In addition, an RLS services document can contain a <list>
element, which in turn can contain <entry>, <entry-ref> and element, which in turn can contain <entry>, <entry-ref> and
<external> elements. The constraints defined for these elements <external> elements. The constraints defined for these elements
in Section 3.4.6 MUST be enforced. in Section 3.4.7 MUST be enforced.
o In some cases, an XCAP client will wish to create a new RLS o In some cases, an XCAP client will wish to create a new RLS
service, and wish to assign it a "vanity URI", such as service, and wish to assign it a "vanity URI", such as
sip:friends@example.com. However, the client does not know sip:friends@example.com. However, the client does not know
whether this URI meets the uniqueness constraints defined above. whether this URI meets the uniqueness constraints defined above.
In that case, it can simply attempt the creation operation, and if In that case, it can simply attempt the creation operation, and if
the result is a 409 that contains a detailed conflict report with the result is a 409 that contains a detailed conflict report with
the <uniqueness-failure> element, the client knows that the URI the <uniqueness-failure> element, the client knows that the URI
could not be assigned. It can then retry with a different vanity could not be assigned. It can then retry with a different vanity
URI, or use one of the suggestions in the detailed conflict URI, or use one of the suggestions in the detailed conflict
report. report.
o If the client wishes to create a new RLS service, and it doesnt o If the client wishes to create a new RLS service, and it doesnt
care what the URI is, the client creates a random one, and care what the URI is, the client creates a random one, and
attempts the creation operation. As discussed in [10], if this attempts the creation operation. As discussed in [10], if this
should fail with a uniqueness conflict, the client can retry with should fail with a uniqueness conflict, the client can retry with
different URIs with increasing randomness. different URIs with increasing randomness.
4.4.5 Data Semantics 4.4.6 Data Semantics
Semantics for the document content are provided in Section 4.1. Semantics for the document content are provided in Section 4.1.
4.4.6 Naming Conventions 4.4.7 Naming Conventions
Typically, there are two distinct XCAP clients that access RLS Typically, there are two distinct XCAP clients that access RLS
services documents. The first is a client acting on behalf of the services documents. The first is a client acting on behalf of the
end user in the system. This client edits and writes both resource end user in the system. This client edits and writes both resource
lists and RLS services documents as they are created or modified by lists and RLS services documents as they are created or modified by
the end user. The other XCAP client is the RLS itself, which reads the end user. The other XCAP client is the RLS itself, which reads
the RLS services documents in order to process SUBSCRIBE requests. the RLS services documents in order to process SUBSCRIBE requests.
To make it easier for an RLS to find the <service> element for a To make it easier for an RLS to find the <service> element for a
particular URI, the XCAP server maintains, within the global tree, a particular URI, the XCAP server maintains, within the global tree, a
skipping to change at page 19, line 42 skipping to change at page 19, line 43
its RLS services within the document named "index". If the root its RLS services within the document named "index". If the root
services URI is http://xcap.example.com/root, for user "joe" the URI services URI is http://xcap.example.com/root, for user "joe" the URI
for this document would be: for this document would be:
http://xcap.example.com/root/rls-services/users/joe/index http://xcap.example.com/root/rls-services/users/joe/index
If a client elects to define RLS services in a different document, If a client elects to define RLS services in a different document,
this document will not be "picked up" in the global index, and this document will not be "picked up" in the global index, and
therefore, not used as an RLS service. therefore, not used as an RLS service.
4.4.7 Resource Interdependencies 4.4.8 Resource Interdependencies
As with other application usages, the XML schema along with the XCAP As with other application usages, the XML schema along with the XCAP
resource naming conventions describes most of the resource resource naming conventions describes most of the resource
interdependencies applicable to this application usage. interdependencies applicable to this application usage.
This application usage defines an additional resource interdependence This application usage defines an additional resource interdependence
between a single document in the global tree and all documents in the between a single document in the global tree and all documents in the
user tree with the name "index". This global document is formed as user tree with the name "index". This global document is formed as
the union of all of the index documents for all users within the same the union of all of the index documents for all users within the same
XCAP root. In this case, the union operation implies that each XCAP root. In this case, the union operation implies that each
skipping to change at page 21, line 27 skipping to change at page 21, line 27
<list name="marketing"> <list name="marketing">
<rl:entry uri="sip:joe@example.com"/> <rl:entry uri="sip:joe@example.com"/>
<rl:entry uri="sip:sudhir@example.com"/> <rl:entry uri="sip:sudhir@example.com"/>
</list> </list>
<packages> <packages>
<package>presence</package> <package>presence</package>
</packages> </packages>
</service> </service>
</rls-services> </rls-services>
The server MUST, at all times, be capable of processing requests made Requests made against the global document MUST generate responses
against the global document, and its contents MUST reflect the that reflect the most recent state of all the relevant user
current state of all the relevant user documents. This requirement documents. This requirement does not imply that the server must
does not imply that the server must actually store this global actually store this global document. It is anticipated that most
document. It is anticipated that most systems will dynamically systems will dynamically construct the responses to any particular
construct the responses to any particular request against the request against the document resource.
document resource.
The uniqueness constraint on the "uri" attribute of <service> will The uniqueness constraint on the "uri" attribute of <service> will
ensure that no two <service> elements in the global document have the ensure that no two <service> elements in the global document have the
same value of that attribute. same value of that attribute.
4.4.8 Authorization Policies 4.4.9 Authorization Policies
This application usage does not modify the default XCAP authorization This application usage does not modify the default XCAP authorization
policy, which is that only a user can read, write or modify their own policy, which is that only a user can read, write or modify their own
documents. A server can allow priveleged users to modify documents documents. A server can allow privileged users to modify documents
that they don't own, but the establishment and indication of such that they don't own, but the establishment and indication of such
policies is outside the scope of this document. It is anticipated policies is outside the scope of this document. It is anticipated
that a future application usage will define which users are allowed that a future application usage will define which users are allowed
to modify an RLS services document. to modify an RLS services document.
The index document maintained in the global tree represents sensitive The index document maintained in the global tree represents sensitive
information, as it contains the union of all of the information for information, as it contains the union of all of the information for
all users on the server. As such, its access MUST be restricted to all users on the server. As such, its access MUST be restricted to
trusted elements within domain of the server. Typically, this would trusted elements within domain of the server. Typically, this would
be limited to the RLSs that need access to this document. be limited to the RLSs that need access to this document.
skipping to change at page 22, line 21 skipping to change at page 22, line 20
When an RLS receives a SUBSCRIBE request for a URI (present in the When an RLS receives a SUBSCRIBE request for a URI (present in the
Request URI), it obtains the <service> element whose uri attribute Request URI), it obtains the <service> element whose uri attribute
matches (based on URI equality) the URI in the SUBSCRIBE request. matches (based on URI equality) the URI in the SUBSCRIBE request.
This document makes no normative statements on how this might be This document makes no normative statements on how this might be
accomplished. The following paragraph provides one possible accomplished. The following paragraph provides one possible
approach. approach.
The RLS canonicalizes the Request URI as described in Section 5. It The RLS canonicalizes the Request URI as described in Section 5. It
then performs an XCAP GET operation against the URI formed by then performs an XCAP GET operation against the URI formed by
combining the XCAP root with the document selector of the global combining the XCAP root with the document selector of the global
index with a node selector of the form "rls-services/ index with a node selector of the form
service[@uri=<canonical-uri>]", where <canonical-uri> is the "rls-services/service[@uri=<canonical-uri>]", where <canonical-uri>
canonicalized version of the Request URI. If the response is a 200 is the canonicalized version of the Request URI. If the response is
OK, it will contain the service definition for that URI. a 200 OK, it will contain the service definition for that URI.
Once the <service> element has been obtained, it is examined. If the Once the <service> element has been obtained, it is examined. If the
<packages> element is present, and the event package in the SUBSCRIBE <packages> element is present, and the event package in the SUBSCRIBE
request is not amongst those listed in the <package> elements within request is not amongst those listed in the <package> elements within
<packages>, the request MUST be rejected with a 489 (Bad Event) <packages>, the request MUST be rejected with a 489 (Bad Event)
response code, as described in [14]. Otherwise, it SHOULD be response code, as described in [14]. Otherwise, it SHOULD be
processed. The next step is to authorize that the client is allowed processed. The next step is to authorize that the client is allowed
to subscribe to the resource. This can be done using the data to subscribe to the resource. This can be done using the data
defined in [13], for example. Assuming the subscriber is authorized defined in [13], for example. Assuming the subscriber is authorized
to subscribe to that resource, the subscription is processed to subscribe to that resource, the subscription is processed
skipping to change at page 22, line 48 skipping to change at page 22, line 47
extracted. If the <service> element had a <resource-list> element, extracted. If the <service> element had a <resource-list> element,
its URI content is dereferenced. The result should be a <list> its URI content is dereferenced. The result should be a <list>
element. If it is not, the request SHOULD be rejected with a 502 element. If it is not, the request SHOULD be rejected with a 502
(Bad Gateway). Otherwise, that <list> element is extracted. (Bad Gateway). Otherwise, that <list> element is extracted.
At this point the RLS has a <list> element in its possession. The At this point the RLS has a <list> element in its possession. The
next step is to obtain a flat list of URIs from this element. To do next step is to obtain a flat list of URIs from this element. To do
that, it traverses the tree of elements rooted in the <list> element. that, it traverses the tree of elements rooted in the <list> element.
Before traversal begins, the RLS initializes two lists - the "flat Before traversal begins, the RLS initializes two lists - the "flat
list", which will contain the flat list of URI after traversal, and list", which will contain the flat list of URI after traversal, and
the "traversed list", which contains a list of HTTP URLs in the "traversed list", which contains a list of HTTP URIs in
<external> elements that have already been visited. Once these lists <external> elements that have already been visited. Once these lists
are initialized, tree traversal begins. A server can use any are initialized, tree traversal begins. A server can use any
tree-traversal ordering it likes, such as depth first search or tree-traversal ordering it likes, such as depth first search or
breadth first search. The processing at each element in the tree breadth first search. The processing at each element in the tree
depends on the name of the element: depends on the name of the element:
o If the element is <entry> the URI in the "uri" attribute of the o If the element is <entry> the URI in the "uri" attribute of the
element is added to the flat list if it is not already present element is added to the flat list if it is not already present
(based on case sensitive string equality) in that list, and the (based on case sensitive string equality) in that list, and the
URI scheme represents one that can be used to service URI scheme represents one that can be used to service
subscriptions, such as SIP [4] and pres [16]. subscriptions, such as SIP [4] and pres [16].
o If the element is an <entry-ref>, the relative path reference o If the element is an <entry-ref>, the relative path reference
making up the value of the "ref" attribute is resolved into an making up the value of the "ref" attribute is resolved into an
absolute URL. This is done using the procedures defined in absolute URI. This is done using the procedures defined in
Section 5.2 of RFC 2396 [7], using the XCAP root of the RLS Section 5.2 of RFC 3986 [7], using the XCAP root of the RLS
services document as the base URL. This absolute URL is resolved. services document as the base URI. This absolute URI is resolved.
If the result is not a 200 OK containing a <entry> element, the If the result is not a 200 OK containing a <entry> element, the
SUBSCRIBE request SHOULD be rejected with a 502 (Bad Gateway). SUBSCRIBE request SHOULD be rejected with a 502 (Bad Gateway).
Otherwise, the <entry> element returned is processed as described Otherwise, the <entry> element returned is processed as described
in the previous step. in the previous step.
o If the element is an <external> element, the absolute URL making o If the element is an <external> element, the absolute URI making
up the value of the "anchor" attribute of the element is examined. up the value of the "anchor" attribute of the element is examined.
If the URL is on the traversed list, the server MUST cease If the URI is on the traversed list, the server MUST cease
traversing the tree, and SHOULD reject the SUBSCRIBE request with traversing the tree, and SHOULD reject the SUBSCRIBE request with
a 502 (Bad Gateway). If the URL is not on the traversed list, the a 502 (Bad Gateway). If the URI is not on the traversed list, the
server adds the URL to the traversed list, and de-references the server adds the URI to the traversed list, and de-references the
URL. If the result is not a 200 OK containing an <list> element, URI. If the result is not a 200 OK containing an <list> element,
the SUBSCRIBE request SHOULD be rejected with a 502 (Bad Gateway). the SUBSCRIBE request SHOULD be rejected with a 502 (Bad Gateway).
Otherwise, the RLS replaces the <external> element in its local Otherwise, the RLS replaces the <external> element in its local
copy of the tree with the <list> element that was returned, and copy of the tree with the <list> element that was returned, and
tree traversal continues. tree traversal continues.
Because the <external> element is used to dynamically construct the Because the <external> element is used to dynamically construct the
tree, there is a posibility of recursive evaluation of references. tree, there is a posibility of recursive evaluation of references.
The traversed list is used to prevent this from happening. The traversed list is used to prevent this from happening.
Once the tree has been traversed, the RLS can create virtual Once the tree has been traversed, the RLS can create virtual
skipping to change at page 27, line 12 skipping to change at page 27, line 12
Published specification: RFC XXXX [[NOTE TO IANA/RFC-EDITOR: Published specification: RFC XXXX [[NOTE TO IANA/RFC-EDITOR:
Please replace XXXX with the RFC number of this specification]] Please replace XXXX with the RFC number of this specification]]
Applications which use this media type: This document type has Applications which use this media type: This document type has
been used to support subscriptions to lists of users [15] for been used to support subscriptions to lists of users [15] for
SIP-based presence [12]. SIP-based presence [12].
Additional Information: Additional Information:
Magic Number: None Magic Number: None
File Extension: .rl or .xml File Extension: .rl
Macintosh file type code: "TEXT" Macintosh file type code: "TEXT"
Personal and email address for further information: Jonathan Personal and email address for further information: Jonathan
Rosenberg, jdrosen@jdrosen.net Rosenberg, jdrosen@jdrosen.net
Intended usage: COMMON Intended usage: COMMON
Author/Change controller: The IETF. Author/Change controller: The IETF.
skipping to change at page 28, line 9 skipping to change at page 28, line 9
Please replace XXXX with the RFC number of this specification]] Please replace XXXX with the RFC number of this specification]]
Applications which use this media type: This document type has Applications which use this media type: This document type has
been used to support subscriptions to lists of users [15] for been used to support subscriptions to lists of users [15] for
SIP-based presence [12]. SIP-based presence [12].
Additional Information: Additional Information:
Magic Number: None Magic Number: None
File Extension: .rs or .xml File Extension: .rs
Macintosh file type code: "TEXT" Macintosh file type code: "TEXT"
Personal and email address for further information: Jonathan Personal and email address for further information: Jonathan
Rosenberg, jdrosen@jdrosen.net Rosenberg, jdrosen@jdrosen.net
Intended usage: COMMON Intended usage: COMMON
Author/Change controller: The IETF. Author/Change controller: The IETF.
skipping to change at page 30, line 20 skipping to change at page 30, line 20
URI: urn:ietf:params:xml:schema:rls-services URI: urn:ietf:params:xml:schema:rls-services
Registrant Contact: IETF, SIMPLE working group, (simple@ietf.org), Registrant Contact: IETF, SIMPLE working group, (simple@ietf.org),
Jonathan Rosenberg (jdrosen@jdrosen.net). Jonathan Rosenberg (jdrosen@jdrosen.net).
The XML for this schema can be found as the sole content of The XML for this schema can be found as the sole content of
Section 4.2. Section 4.2.
9. Acknowledgements 9. Acknowledgements
The authors would like to thank Hisham Khartabil and Jari Urpalainen The authors would like to thank Hisham Khartabil, Jari Urpalainen and
for their comments and input. Thanks to Ted Hardie for his Spencer Dawkins for their comments and input. Thanks to Ted Hardie
encouragement and support of this work. for his encouragement and support of this work.
10. References 10. References
10.1 Normative References 10.1 Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997. Levels", BCP 14, RFC 2119, March 1997.
[2] Bray, T., Paoli, J., Sperberg-McQueen, C. and E. Maler, [2] Bray, T., Paoli, J., Sperberg-McQueen, C. and E. Maler,
"Extensible Markup Language (XML) 1.0 (Second Edition)", W3C "Extensible Markup Language (XML) 1.0 (Second Edition)", W3C
skipping to change at page 30, line 48 skipping to change at page 30, line 48
Peterson, J., Sparks, R., Handley, M. and E. Schooler, "SIP: Peterson, J., Sparks, R., Handley, M. and E. Schooler, "SIP:
Session Initiation Protocol", RFC 3261, June 2002. Session Initiation Protocol", RFC 3261, June 2002.
[5] Murata, M., St. Laurent, S. and D. Kohn, "XML Media Types", RFC [5] Murata, M., St. Laurent, S. and D. Kohn, "XML Media Types", RFC
3023, January 2001. 3023, January 2001.
[6] Moats, R., "A URN Namespace for IETF Documents", RFC 2648, [6] Moats, R., "A URN Namespace for IETF Documents", RFC 2648,
August 1999. August 1999.
[7] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform [7] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform
Resource Identifiers (URI): Generic Syntax", RFC 2396, August Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986,
1998. January 2005.
[8] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, [8] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
January 2004. January 2004.
[9] Freed, N., Klensin, J. and J. Postel, "Multipurpose Internet [9] Freed, N., Klensin, J. and J. Postel, "Multipurpose Internet
Mail Extensions (MIME) Part Four: Registration Procedures", BCP Mail Extensions (MIME) Part Four: Registration Procedures", BCP
13, RFC 2048, November 1996. 13, RFC 2048, November 1996.
[10] Rosenberg, J., "The Extensible Markup Language (XML) [10] Rosenberg, J., "The Extensible Markup Language (XML)
Configuration Access Protocol (XCAP)", Configuration Access Protocol (XCAP)",
draft-ietf-simple-xcap-03 (work in progress), July 2004. draft-ietf-simple-xcap-05 (work in progress), November 2004.
10.2 Informative References 10.2 Informative References
[11] Day, M., Rosenberg, J. and H. Sugano, "A Model for Presence and [11] Day, M., Rosenberg, J. and H. Sugano, "A Model for Presence and
Instant Messaging", RFC 2778, February 2000. Instant Messaging", RFC 2778, February 2000.
[12] Rosenberg, J., "A Presence Event Package for the Session [12] Rosenberg, J., "A Presence Event Package for the Session
Initiation Protocol (SIP)", RFC 3856, August 2004. Initiation Protocol (SIP)", RFC 3856, August 2004.
[13] Rosenberg, J., "Presence Authorization Rules", [13] Rosenberg, J., "Presence Authorization Rules",
draft-ietf-simple-presence-rules-00 (work in progress), May draft-ietf-simple-presence-rules-01 (work in progress), October
2004. 2004.
[14] Roach, A., "Session Initiation Protocol (SIP)-Specific Event [14] Roach, A., "Session Initiation Protocol (SIP)-Specific Event
Notification", RFC 3265, June 2002. Notification", RFC 3265, June 2002.
[15] Roach, A., Rosenberg, J. and B. Campbell, "A Session Initiation [15] Roach, A., Rosenberg, J. and B. Campbell, "A Session Initiation
Protocol (SIP) Event Notification Extension for Resource Protocol (SIP) Event Notification Extension for Resource
Lists", draft-ietf-simple-event-list-05 (work in progress), Lists", draft-ietf-simple-event-list-07 (work in progress),
August 2004. January 2005.
[16] Peterson, J., "Common Profile for Presence (CPP)", RFC 3859, [16] Peterson, J., "Common Profile for Presence (CPP)", RFC 3859,
August 2004. August 2004.
Author's Address Author's Address
Jonathan Rosenberg Jonathan Rosenberg
Cisco Systems Cisco Systems
600 Lanidex Plaza 600 Lanidex Plaza
Parsippany, NJ 07054 Parsippany, NJ 07054
US US
Phone: +1 973 952-5000 Phone: +1 973 952-5000
EMail: jdrosen@dynamicsoft.com EMail: jdrosen@cisco.com
URI: http://www.jdrosen.net URI: http://www.jdrosen.net
Intellectual Property Statement Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information made any independent effort to identify any such rights. Information
skipping to change at page 32, line 41 skipping to change at page 32, line 41
This document and the information contained herein are provided on an This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Copyright Statement Copyright Statement
Copyright (C) The Internet Society (2004). This document is subject Copyright (C) The Internet Society (2005). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights. except as set forth therein, the authors retain all their rights.
Acknowledgment Acknowledgment
Funding for the RFC Editor function is currently provided by the Funding for the RFC Editor function is currently provided by the
Internet Society. Internet Society.
 End of changes. 

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