< draft-shelby-core-resource-directory-04.txt		draft-shelby-core-resource-directory-05.txt >
	CoRE Z. Shelby		CoRE Z. Shelby
	Internet-Draft Sensinode		Internet-Draft Sensinode
	Intended status: Standards Track S. Krco		Intended status: Standards Track S. Krco
	Expires: January 17, 2013 Ericsson		Expires: August 29, 2013 Ericsson
	C. Bormann		C. Bormann
	Universitaet Bremen TZI		Universitaet Bremen TZI
	July 16, 2012		February 25, 2013
	CoRE Resource Directory		CoRE Resource Directory
	draft-shelby-core-resource-directory-04		draft-shelby-core-resource-directory-05
	Abstract		Abstract
	In many M2M applications, direct discovery of resources is not		In many M2M applications, direct discovery of resources is not
	practical due to sleeping nodes, disperse networks, or networks where		practical due to sleeping nodes, disperse networks, or networks where
	multicast traffic is inefficient. These problems can be solved by		multicast traffic is inefficient. These problems can be solved by
	employing an entity called a Resource Directory (RD), which hosts		employing an entity called a Resource Directory (RD), which hosts
	descriptions of resources held on other servers, allowing lookups to		descriptions of resources held on other servers, allowing lookups to
	be performed for those resources. This document specifies the web		be performed for those resources. This document specifies the web
	interfaces that a Resource Directory supports in order for web		interfaces that a Resource Directory supports in order for web
	skipping to change at page 1, line 42 ¶		skipping to change at page 1, line 42 ¶
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute		Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
	Drafts is at http://datatracker.ietf.org/drafts/current/.		Drafts is at http://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	This Internet-Draft will expire on January 17, 2013.		This Internet-Draft will expire on August 29, 2013.
	Copyright Notice		Copyright Notice
	Copyright (c) 2012 IETF Trust and the persons identified as the		Copyright (c) 2013 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(http://trustee.ietf.org/license-info) in effect on the date of		(http://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	skipping to change at page 2, line 27 ¶		skipping to change at page 2, line 27 ¶
	3. Architecture and Use Cases . . . . . . . . . . . . . . . . . . 4		3. Architecture and Use Cases . . . . . . . . . . . . . . . . . . 4
	3.1. Use Case: Cellular M2M . . . . . . . . . . . . . . . . . . 5		3.1. Use Case: Cellular M2M . . . . . . . . . . . . . . . . . . 5
	3.2. Use Case: Home and Building Automation . . . . . . . . . . 6		3.2. Use Case: Home and Building Automation . . . . . . . . . . 6
	4. Simple Directory Discovery . . . . . . . . . . . . . . . . . . 6		4. Simple Directory Discovery . . . . . . . . . . . . . . . . . . 6
	4.1. Finding a Directory Server . . . . . . . . . . . . . . . . 7		4.1. Finding a Directory Server . . . . . . . . . . . . . . . . 7
	5. Resource Directory Function Set . . . . . . . . . . . . . . . 8		5. Resource Directory Function Set . . . . . . . . . . . . . . . 8
	5.1. Discovery . . . . . . . . . . . . . . . . . . . . . . . . 8		5.1. Discovery . . . . . . . . . . . . . . . . . . . . . . . . 8
	5.2. Registration . . . . . . . . . . . . . . . . . . . . . . . 10		5.2. Registration . . . . . . . . . . . . . . . . . . . . . . . 10
	5.3. Update . . . . . . . . . . . . . . . . . . . . . . . . . . 12		5.3. Update . . . . . . . . . . . . . . . . . . . . . . . . . . 12
	5.4. Validation . . . . . . . . . . . . . . . . . . . . . . . . 13		5.4. Validation . . . . . . . . . . . . . . . . . . . . . . . . 13
	5.5. Removal . . . . . . . . . . . . . . . . . . . . . . . . . 14		5.5. Removal . . . . . . . . . . . . . . . . . . . . . . . . . 15
	6. RD Lookup Function Set . . . . . . . . . . . . . . . . . . . . 15		6. Group Function Set . . . . . . . . . . . . . . . . . . . . . . 16
	7. New Link-Format Attributes . . . . . . . . . . . . . . . . . . 18		6.1. Register a Group . . . . . . . . . . . . . . . . . . . . . 16
	7.1. Resource Instance 'ins' attribute . . . . . . . . . . . . 18		6.2. Group Removal . . . . . . . . . . . . . . . . . . . . . . 17
	7.2. Export 'exp' attribute . . . . . . . . . . . . . . . . . . 19		7. RD Lookup Function Set . . . . . . . . . . . . . . . . . . . . 18
	8. Security Considerations . . . . . . . . . . . . . . . . . . . 19		8. New Link-Format Attributes . . . . . . . . . . . . . . . . . . 23
	9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19		8.1. Resource Instance 'ins' attribute . . . . . . . . . . . . 23
	10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 20		8.2. Export 'exp' attribute . . . . . . . . . . . . . . . . . . 23
	11. Changelog . . . . . . . . . . . . . . . . . . . . . . . . . . 20		9. Security Considerations . . . . . . . . . . . . . . . . . . . 24
	12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21		10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24
	12.1. Normative References . . . . . . . . . . . . . . . . . . . 21		11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 24
	12.2. Informative References . . . . . . . . . . . . . . . . . . 21		12. Changelog . . . . . . . . . . . . . . . . . . . . . . . . . . 24
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 22		13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 26
			13.1. Normative References . . . . . . . . . . . . . . . . . . . 26
			13.2. Informative References . . . . . . . . . . . . . . . . . . 26
			Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 26
	1. Introduction		1. Introduction
	The Constrained RESTful Environments (CoRE) work aims at realizing		The Constrained RESTful Environments (CoRE) work aims at realizing
	the REST architecture in a suitable form for the most constrained		the REST architecture in a suitable form for the most constrained
	nodes (e.g. 8-bit microcontrollers with limited RAM and ROM) and		nodes (e.g. 8-bit microcontrollers with limited RAM and ROM) and
	networks (e.g. 6LoWPAN). CoRE is aimed at machine-to-machine (M2M)		networks (e.g. 6LoWPAN). CoRE is aimed at machine-to-machine (M2M)
	applications such as smart energy and building automation.		applications such as smart energy and building automation.
	The discovery of resources offered by a constrained server is very		The discovery of resources offered by a constrained server is very
	important in machine-to-machine applications where there are no		important in machine-to-machine applications where there are no
	humans in the loop and static interfaces result in fragility. The		humans in the loop and static interfaces result in fragility. The
	discovery of resources provided by an HTTP Web Server is typically		discovery of resources provided by an HTTP Web Server is typically
	called Web Linking [RFC5988]. The use of Web Linking for the		called Web Linking [RFC5988]. The use of Web Linking for the
	description and discovery of resources hosted by constrained web		description and discovery of resources hosted by constrained web
	servers is specified by the CoRE Link Format		servers is specified by the CoRE Link Format [RFC6690]. This
	[I-D.ietf-core-link-format]. This specification however only		specification however only describes how to discover resources from
	describes how to discover resources from the web server that hosts		the web server that hosts them by requesting /.well-known/core. In
	them by requesting /.well-known/core. In many M2M scenarios, direct		many M2M scenarios, direct discovery of resources is not practical
	discovery of resources is not practical due to sleeping nodes,		due to sleeping nodes, disperse networks, or networks where multicast
	disperse networks, or networks where multicast traffic is		traffic is inefficient. These problems can be solved by employing an
	inefficient. These problems can be solved by employing an entity		entity called a Resource Directory (RD), which hosts descriptions of
	called a Resource Directory (RD), which hosts descriptions of
	resources held on other servers, allowing lookups to be performed for		resources held on other servers, allowing lookups to be performed for
	those resources.		those resources.
	This document specifies the web interfaces that a Resource Directory		This document specifies the web interfaces that a Resource Directory
	supports in order for web servers to discover the RD and to		supports in order for web servers to discover the RD and to
	registrer, maintain, lookup and remove resources descriptions.		registrer, maintain, lookup and remove resource descriptions.
	Furthermore, new link attributes useful in conjunction with a		Furthermore, new link attributes useful in conjunction with a
	Resource Directory are defined. Although the examples in this		Resource Directory are defined. Although the examples in this
	document show the use of these interfaces with CoAP		document show the use of these interfaces with CoAP
	[I-D.ietf-core-coap], they may be applied in an equivalent manner to		[I-D.ietf-core-coap], they may be applied in an equivalent manner to
	HTTP [RFC2616].		HTTP [RFC2616].
	2. Terminology		2. Terminology
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this		"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
	document are to be interpreted as described in [RFC2119]. The term		document are to be interpreted as described in [RFC2119]. The term
	"byte" is used in its now customary sense as a synonym for "octet".		"byte" is used in its now customary sense as a synonym for "octet".
	This specification requires readers to be familiar with all the terms		This specification requires readers to be familiar with all the terms
	and concepts that are discussed in [RFC5988] and		and concepts that are discussed in [RFC5988] and [RFC6690]. Readers
	[I-D.ietf-core-link-format]. Readers should also be familiar with		should also be familiar with the terms and concepts discussed in
	the terms and concepts discussed in [I-D.ietf-core-coap]. The URI		[I-D.ietf-core-coap]. The URI Template format is used to describe
	Template format is used to describe the REST interfaces defined in		the REST interfaces defined in this specification [RFC6570]. This
	this specification [RFC6570]. This specification makes use of the		specification makes use of the following additional terminology:
	following additional terminology:
	Resource Directory		Resource Directory
	An web entity that stores information about web resources and		An web entity that stores information about web resources and
	implements the REST interfaces defined in this specification for		implements the REST interfaces defined in this specification for
	registration and lookup of those resources.		registration and lookup of those resources.
	Domain		Domain
	In the context of a Resource Directory, a Domain is a logical		In the context of a Resource Directory, a domain is a logical
	grouping of endpoints. All endpoint within a Domain MUST be		grouping of endpoints. All endpoint within a domain MUST be
	unique. This specification assumes that the list of Domains		unique. This specification assumes that the list of Domains
	supported by an RD is pre-configured by that RD.		supported by an RD is pre-configured by that RD.
			Group
			In the context of a Resource Directory, a group is a logical
			grouping of endpoints for the purpose of group communications.
			All groups within a domain MUST be unique.
	Endpoint		Endpoint
	An endpoint (EP) is a term used to describe a web server or client		An endpoint (EP) is a term used to describe a web server or client
	in [I-D.ietf-core-coap]. In the context of this specification an		in [I-D.ietf-core-coap]. In the context of this specification an
	endpoint is used to describe a web server that registers resources		endpoint is used to describe a web server that registers resources
	to the Resource Directory. An endpoint is identified by its		to the Resource Directory. An endpoint is identified by its
	endpoint name, which is included during registration, and MUST be		endpoint name, which is included during registration, and MUST be
	unique within the associated Domain of the registration.		unique within the associated domain of the registration.
	3. Architecture and Use Cases		3. Architecture and Use Cases
	The resource directory architecture is shown in Figure 1. A Resource		The resource directory architecture is shown in Figure 1. A Resource
	Directory (RD) is used as a repository for Web Links [RFC5988] about		Directory (RD) is used as a repository for Web Links [RFC5988] about
	resources hosted on other web servers, which are called endpoints		resources hosted on other web servers, which are called endpoints
	(EP). An endpoint is a web server associated with a port, thus a		(EP). An endpoint is a web server associated with a port, thus a
	physical node may host one or more endpoints. The RD implements a		physical node may host one or more endpoints. The RD implements a
	set of REST interfaces for endpoints to register and maintain sets of		set of REST interfaces for endpoints to register and maintain sets of
	Web Links (called resource directory entries), for the RD to validate		Web Links (called resource directory entries), for the RD to validate
	entries, and for clients to lookup resources from the RD. Endpoints		entries, and for clients to lookup resources from the RD. Endpoints
	themselves can also act as clients. An RD can be logically segmented		themselves can also act as clients. An RD can be logically segmented
	by the use of Domains. The Domain an endpoint is associated with can		by the use of Domains. The domain an endpoint is associated with can
	be defined by the RD or configured by an outside entity.		be defined by the RD or configured by an outside entity.
	Endpoints are assumed to proactively register and maintain resource		Endpoints are assumed to proactively register and maintain resource
	directory entries on the RD, which are soft state and need to be		directory entries on the RD, which are soft state and need to be
	periodially refreshed. An endpoint is provided with interfaces to		periodially refreshed. An endpoint is provided with interfaces to
	register, update and remove a resource directory entry. Furthermore,		register, update and remove a resource directory entry. Furthermore,
	a mechanism to discover a RD using the CoRE Link Format is defined.		a mechanism to discover a RD using the CoRE Link Format is defined.
	It is also possible for an RD to proactively discover Web Links from		It is also possible for an RD to proactively discover Web Links from
	endpoints and add them as resource directory entries, or to validate		endpoints and add them as resource directory entries, or to validate
	existing resource directory entries. A lookup interface for		existing resource directory entries. A lookup interface for
	skipping to change at page 6, line 41 ¶		skipping to change at page 6, line 44 ¶
	implement the Resource Directory Function Set and thus explicitly		implement the Resource Directory Function Set and thus explicitly
	register with a Resource Directory (or other such directory server).		register with a Resource Directory (or other such directory server).
	Instead, simple endpoints can implement the generic Simple Directory		Instead, simple endpoints can implement the generic Simple Directory
	Discovery approach described in this section. An RD implementing		Discovery approach described in this section. An RD implementing
	this specification MUST implement Simple Directory Discovery.		this specification MUST implement Simple Directory Discovery.
	However, there may be security reasons why this form of directory		However, there may be security reasons why this form of directory
	discovery would be disabled.		discovery would be disabled.
	This approach requires that the endpoint makes the hosted resources		This approach requires that the endpoint makes the hosted resources
	that it wants discovered available as links on its /.well-known/core		that it wants discovered available as links on its /.well-known/core
	interface as specified in [I-D.ietf-core-link-format].		interface as specified in [RFC6690].
	The endpoint then finds one or more IP addresses of the directory		The endpoint then finds one or more IP addresses of the directory
	server it wants to know about its resources as described in		server it wants to know about its resources as described in
	Section 4.1.		Section 4.1.
	An endpoint that wants to make itself discoverable occasionally sends		An endpoint that wants to make itself discoverable occasionally sends
	a POST request to the /.well-known/core URI of any candidate		a POST request to the /.well-known/core URI of any candidate
	directory server that it finds. The body of the POST request is		directory server that it finds. The body of the POST request is
	either		either
	o empty, in which case the directory server is encouraged by this		o empty, in which case the directory server is encouraged by this
	POST request to perform GET requests at the requesting server's		POST request to perform GET requests at the requesting server's
	default discovery URI.		default discovery URI.
	or		or
	o a link-format document, which indicates the specific services that		o a link-format document, which indicates the specific services that
	the requesting server wants to make known to the directory server.		the requesting server wants to make known to the directory server.
	The directory server integrates the information it received this way		The directory server integrates the information it received this way
	skipping to change at page 7, line 40 ¶		skipping to change at page 7, line 44 ¶
	4.1. Finding a Directory Server		4.1. Finding a Directory Server
	Endpoints that want to contact a directory server can obtain		Endpoints that want to contact a directory server can obtain
	candidate IP addresses for such servers in a number of ways.		candidate IP addresses for such servers in a number of ways.
	In a 6LoWPAN, good candidates can be taken from:		In a 6LoWPAN, good candidates can be taken from:
	o specific static configuration (e.g., anycast addresses), if any,		o specific static configuration (e.g., anycast addresses), if any,
	o the ABRO option of 6LoWPAN-ND [I-D.ietf-6lowpan-nd],		o the ABRO option of 6LoWPAN-ND [RFC6775],
	o other ND options that happen to point to servers (such as RDNSS),		o other ND options that happen to point to servers (such as RDNSS),
	o DHCPv6 options that might be defined later.		o DHCPv6 options that might be defined later.
	In networks with more inexpensive use of multicast, the candidate IP		In networks with more inexpensive use of multicast, the candidate IP
	address may be a well-known multicast address, i.e. directory servers		address may be a well-known multicast address, i.e. directory servers
	are found by simply sending POST requests to that well-known		are found by simply sending POST requests to that well-known
	multicast address (details TBD).		multicast address (details TBD).
	As some of these sources are just (more or less educated) guesses,		As some of these sources are just (more or less educated) guesses,
	endpoints MUST make use of any error messages to very strictly rate-		endpoints MUST make use of any error messages to very strictly rate-
	limit requests to candidate IP addresses that don't work out. E.g.,		limit requests to candidate IP addresses that don't work out. E.g.,
	skipping to change at page 8, line 44 ¶		skipping to change at page 8, line 48 ¶
	5.1. Discovery		5.1. Discovery
	Before an endpoint can make use of an RD, it must first know the RD's		Before an endpoint can make use of an RD, it must first know the RD's
	IP address, port and the path of its RD Function Set. There can be		IP address, port and the path of its RD Function Set. There can be
	several mechanisms for discovering the RD including assuming a		several mechanisms for discovering the RD including assuming a
	default location (e.g. on an Edge Router in a LoWPAN), by assigning		default location (e.g. on an Edge Router in a LoWPAN), by assigning
	an anycast address to the RD, using DHCP, or by discovering the RD		an anycast address to the RD, using DHCP, or by discovering the RD
	using the CoRE Link Format (also see Section 4.1). This section		using the CoRE Link Format (also see Section 4.1). This section
	defines discovery of the RD using the well-known interface of the		defines discovery of the RD using the well-known interface of the
	CoRE Link Format [I-D.ietf-core-link-format] as the required		CoRE Link Format [RFC6690] as the required mechanism. It is however
	mechanism. It is however expected that RDs will also be discoverable		expected that RDs will also be discoverable via other methods
	via other methods depending on the deployment.		depending on the deployment.
	Discovery is performed by sending either a multicast or unicast GET		Discovery is performed by sending either a multicast or unicast GET
	request to /.well-known/core and including a Resource Type (rt)		request to /.well-known/core and including a Resource Type (rt)
	parameter [I-D.ietf-core-link-format] with the value "core.rd" in the		parameter [RFC6690] with the value "core.rd" in the query string.
	query string. Likewise, a Resource Type parameter value of "core.rd-		Likewise, a Resource Type parameter value of "core.rd-lookup" is used
	lookup" is used to discover the RD Lookup Function Set. Upon success,		to discover the RD Lookup Function Set. Upon success, the response
	the response will contain a payload with a link format entry for each		will contain a payload with a link format entry for each RD
	RD discovered, with the URL indicating the root resource of the RD.		discovered, with the URL indicating the root resource of the RD.
	When performing multicast discovery, the multicast IP address used		When performing multicast discovery, the multicast IP address used
	will depend on the scope required and the multicast capabilities of		will depend on the scope required and the multicast capabilities of
	the network.		the network.
	An RD implementation of this specification MUST support query		An RD implementation of this specification MUST support query
	filtering for the rt parameter as defined in		filtering for the rt parameter as defined in [RFC6690].
	[I-D.ietf-core-link-format].
	The discovery request interface is specified as follows:		The discovery request interface is specified as follows:
	Interaction: EP -> RD		Interaction: EP -> RD
	Method: GET		Method: GET
	URI Template: /.well-known/core{?rt}		URI Template: /.well-known/core{?rt}
	URI Template Variables:		URI Template Variables:
	skipping to change at page 10, line 17 ¶		skipping to change at page 10, line 17 ¶
	| ----- GET /.well-known/core?rt=core.rd* ------> |		| ----- GET /.well-known/core?rt=core.rd* ------> |
	| |		| |
	| |		| |
	| <---- 2.05 Content "</rd>; rt="core.rd" ------ |		| <---- 2.05 Content "</rd>; rt="core.rd" ------ |
	| |		| |
	Req: GET coap://[ff02::1]/.well-known/core?rt=core.rd*		Req: GET coap://[ff02::1]/.well-known/core?rt=core.rd*
	Res: 2.05 Content		Res: 2.05 Content
	</rd>;rt="core.rd",		</rd>;rt="core.rd",
	</rd-lookup>;rt="core.rd-lookup"		</rd-lookup>;rt="core.rd-lookup",
			</rd-group>;rt="core.rd-group"
	5.2. Registration		5.2. Registration
	After discovering the location of an RD Function Set, an endpoint MAY		After discovering the location of an RD Function Set, an endpoint MAY
	register its resources using the registration interface. This		register its resources using the registration interface. This
	interface accepts a POST from an endpoint containing the list of		interface accepts a POST from an endpoint containing the list of
	resources to be added to the directory as the message payload in the		resources to be added to the directory as the message payload in the
	CoRE Link Format along with query string parameters indicating the		CoRE Link Format along with query string parameters indicating the
	name of the endpoint, its Domain and the lifetime of the		name of the endpoint, its domain and the lifetime of the
	registration. All parameters except the endpoint name are optional.		registration. All parameters except the endpoint name are optional.
	The RD then creates a new resource or updates an existing resource in		It is expected that other specifications MAY define further
	the RD and returns its location. An endpoint MUST use that location		parameters (it is to be determined if a registry of parameters is
	when refreshing registrations using this interface. endpoint		needed for this purpose). The RD then creates a new resource or
	resources in the RD are kept active for the period indicated by the		updates an existing resource in the RD and returns its location. An
	lifetime parameter. The endpoint is responsible for refreshing the		endpoint MUST use that location when refreshing registrations using
	entry within this period using either the registration or update		this interface. Endpoint resources in the RD are kept active for the
	interface. The registration interface MUST be implemented to be		period indicated by the lifetime parameter. The endpoint is
	idempotent, so that registering twice with the same endpoint		responsible for refreshing the entry within this period using either
	parameter does not create multiple RD entries.		the registration or update interface. The registration interface
			MUST be implemented to be idempotent, so that registering twice with
			the same endpoint parameter does not create multiple RD entries.
	The registration request interface is specified as follows:		The registration request interface is specified as follows:
	Interaction: EP -> RD		Interaction: EP -> RD
	Method: POST		Method: POST
			URI Template: /{+rd}{?ep,d,et,lt,con}
	URI Template: /{+rd}{?ep,d,rt,lt,con}
	URI Template Variables:		URI Template Variables:
	rd := RD Function Set path (mandatory). This is the path of the		rd := RD Function Set path (mandatory). This is the path of the
	RD Function Set. An RD SHOULD use the value "rd" for this		RD Function Set. An RD SHOULD use the value "rd" for this
	variable whenever possible.		variable whenever possible.
	ep := Endpoint (mandatory). The endpoint identifier or name of		ep := Endpoint (mandatory). The endpoint identifier or name of
	the registering node, unique within that Domain. The maximum		the registering node, unique within that domain. The maximum
	length of this parameter is 63 bytes.		length of this parameter is 63 bytes.
	d := Domain (optional). The Domain to which this endpoint		d := Domain (optional). The domain to which this endpoint
	belongs. The maximum length of this parameter is 63 bytes.		belongs. The maximum length of this parameter is 63 bytes.
	Optional. When this parameter is elided, the RD MAY associate		Optional. When this parameter is elided, the RD MAY associate
	the endpoint with a configured default Domain.		the endpoint with a configured default domain.
	rt := Endpoint Type (optional). The semantic type of the		et := Endpoint Type (optional). The semantic type of the
	endpoint. The maximum length of this parameter is 63 bytes.		endpoint. The maximum length of this parameter is 63 bytes.
	Optional.		Optional.
	lt := Lifetime (optional). Lifetime of the registration in		lt := Lifetime (optional). Lifetime of the registration in
	seconds. Range of 60-4294967295. If no lifetime is included,		seconds. Range of 60-4294967295. If no lifetime is included,
	a default value of 86400 (24 hours) SHOULD be assumed.		a default value of 86400 (24 hours) SHOULD be assumed.
	con := Context (optional). This parameter sets the scheme,		con := Context (optional). This parameter sets the scheme,
	address and port at which this server is available in the form		address and port at which this server is available in the form
	scheme://host:port. Optional. In the absence of this		scheme://host:port. Optional. In the absence of this
	parameter the scheme of the protocol, source IP address and		parameter the scheme of the protocol, source IP address and
	source port used to register are assumed.		source port of the register request are assumed.
	Content-Type: application/link-format		Content-Type: application/link-format
	The following response codes are defined for this interface:		The following response codes are defined for this interface:
	Success: 2.01 "Created". The Location header MUST be included with		Success: 2.01 "Created". The Location header MUST be included with
	the new resource entry for the endpoint. This Location MUST be a		the new resource entry for the endpoint. This Location MUST be a
	stable identifier generated by the RD as it is used for all		stable identifier generated by the RD as it is used for all
	subsequent operations on this registration (update, delete).		subsequent operations on this registration (update, delete).
	skipping to change at page 12, line 15 ¶		skipping to change at page 12, line 16 ¶
	EP RD		EP RD
	| |		| |
	| --- POST /rd?ep=node1 "</sensors..." -------> |		| --- POST /rd?ep=node1 "</sensors..." -------> |
	| |		| |
	| |		| |
	| <-- 2.01 Created Location: /rd/4521 ---------- |		| <-- 2.01 Created Location: /rd/4521 ---------- |
	| |		| |
	Req: POST coap://rd.example.com/rd?ep=node1		Req: POST coap://rd.example.com/rd?ep=node1
	Payload:		Payload:
	</sensors/temp>;ct=41;rt="TemperatureC";if="sensor",		</sensors/temp>;ct=41;rt="temperature-c";if="sensor",
	</sensors/light>;ct=41;rt="LightLux";if="sensor"		</sensors/light>;ct=41;rt="light-lux";if="sensor"
	Res: 2.01 Created		Res: 2.01 Created
	Location: /rd/4521		Location: /rd/4521
	5.3. Update		5.3. Update
	The update interface is used by an endpoint to refresh or update its		The update interface is used by an endpoint to refresh or update its
	registration with an RD. To use the interface, the endpoint sends a		registration with an RD. To use the interface, the endpoint sends a
	PUT request to the resource returned in the Location option in the		PUT request to the resource returned in the Location option in the
	response to the first registration. An update MAY contain		response to the first registration. An update MAY contain
	registration parameters or a payload in CoRE Link Format if there		registration parameters if there have been changes since the last
	have been changes since the last registration or update. Paremeters		registration or update. Parameters that have not changed SHOULD NOT
	that have not changed SHOULD NOT be included in an update.		be included in an update. Upon receiving an update request, the RD
			resets the timeout for that endpoint and stores the values of the
			parameters included in the update (if any).
	The update request interface is specified as follows:		The update request interface is specified as follows:
	Interaction: EP -> RD		Interaction: EP -> RD
	Method: PUT		Method: PUT
	URI Template: /{+location}{?rt,lt,con}		URI Template: /{+location}{?et,lt,con}
	URI Template Variables:		URI Template Variables:
	location := This is the Location path returned by the RD as a		location := This is the Location path returned by the RD as a
	result of a successful registration.		result of a successful registration.
	rt := Endpoint Type (optional). The semantic type of the		et := Endpoint Type (optional). The semantic type of the
	endpoint. The maximum length of this parameter is 63 btyes.		endpoint. The maximum length of this parameter is 63 btyes.
	Optional.		Optional.
	lt := Lifetime (optional). Lifetime of the registration in		lt := Lifetime (optional). Lifetime of the registration in
	seconds. Range of 60-4294967295. If no lifetime is included,		seconds. Range of 60-4294967295. If no lifetime is included,
	a default value of 86400 (24 hours) SHOULD be assumed.		a default value of 86400 (24 hours) SHOULD be assumed.
	con := Context (optional). This parameter sets the scheme,		con := Context (optional). This parameter sets the scheme,
	address and port at which this server is available in the form		address and port at which this server is available in the form
	scheme://host:port. Optional. In the absence of this		scheme://host:port. Optional. In the absence of this
	parameter the scheme of the protocol, source IP address and		parameter the scheme of the protocol, source IP address and
	source port used to register are assumed.		source port used to register are assumed.
	Content-Type: application/link-format (if any)		Content-Type: None
	The following response codes are defined for this interface:		The following response codes are defined for this interface:
	Success: 2.04 "Changed" in case the resource and/or lifetime was		Success: 2.04 "Changed" in the update was successfully processed.
	successfully updated
	Failure: 4.00 "Bad Request". Malformed request.		Failure: 4.00 "Bad Request". Malformed request.
	Failure: 5.03 "Service Unavailable". Service could not perform the		Failure: 5.03 "Service Unavailable". Service could not perform the
	operation.		operation.
	The following example shows an endpoint updating a new set of		The following example shows an endpoint updating a new set of
	resources to an RD using this interface.		resources to an RD using this interface.
	EP RD		EP RD
	| |		| |
	| --- PUT /rd/4521 "</sensors..." ------------> |		| --- PUT /rd/4521 --------------------------> |
	| |		| |
	| |		| |
	| <-- 2.04 Changed ---------------------------- |		| <-- 2.04 Changed ---------------------------- |
	| |		| |
	Req: PUT /rd/4521		Req: PUT /rd/4521
	Payload:
	</sensors/temp/1>;ct=41;ins="Indoor";rt="TemperatureC";if="sensor",
	</sensors/temp/2>;ct=41;ins="Outdoor";rt="TemperatureC";if="sensor",
	</sensors/light>;ct=41;rt="LightLux";if="sensor"
	Res: 2.04 Changed		Res: 2.04 Changed
	5.4. Validation		5.4. Validation
	In some cases, an RD may want to validate that it has the latest		In some cases, an RD may want to validate that it has the latest
	version of an endpoint's resources. This can be performed with a GET		version of an endpoint's resources. This can be performed with a GET
	on the well-known interface of the CoRE Link Format including the		on the well-known interface of the CoRE Link Format including the
	latest ETag stored for that endpoint. For the purpose of validation,		latest ETag stored for that endpoint. For the purpose of validation,
	an endpoint implementing this specification SHOULD support ETag		an endpoint implementing this specification SHOULD support ETag
	skipping to change at page 15, line 42 ¶		skipping to change at page 16, line 5 ¶
	| --- DELETE /rd/4521 ------------------------> |		| --- DELETE /rd/4521 ------------------------> |
	| |		| |
	| |		| |
	| <-- 2.02 Deleted ---------------------------- |		| <-- 2.02 Deleted ---------------------------- |
	| |		| |
	Req: DELETE /rd/4521		Req: DELETE /rd/4521
	Res: 2.02 Deleted		Res: 2.02 Deleted
	6. RD Lookup Function Set		6. Group Function Set
			This section defines a function set for the creation of groups of
			endpoints for the purpose of managing and looking up endpoints for
			group operations. The group function set is similar to the resource
			directory function set, in that a group may be created or removed.
			However unlike an endpoint entry, a group entry consists of a list of
			endpoints and does not have a lifetime associated with it. In order
			to make use of multicast requests with CoAP, a group MAY have a
			multicast address associated with it.
			6.1. Register a Group
			In order to create a group, a management entity used to configure
			groups, makes a request to the RD indicating the name of the group to
			create (or update), the optional domain the group belongs to, and the
			optional multicast address of the group. The registration message
			includes the list of endpoints that belong to that group. If an
			endpoint has already registered with the RD, the RD attempts to use
			the context of the endpoint from its RD endpoint entry. If the
			client registering the group knows the endpoint has already
			registered, then it MAY send a blank target URI for that endpoint
			link when registering the group.
			The registration request interface is specified as follows:
			Interaction: Manager -> RD
			Method: POST
			URI Template: /{+rd-group}{?gp,d,con}
			URI Template Variables:
			rd-group := RD Group Function Set path (mandatory). This is the
			path of the RD Group Function Set. An RD SHOULD use the value
			"rd-group" for this variable whenever possible.
			gp := Group Name (mandatory). The name of the group to be
			created or replaced, unique within that domain. The maximum
			length of this parameter is 63 bytes.
			d := Domain (optional). The domain to which this group belongs.
			The maximum length of this parameter is 63 bytes. Optional.
			When this parameter is elided, the RD MAY associate the
			endpoint with a configured default domain.
			con := Context (optional). This parameter is used to set the IP
			multicast address at which this server is available in the form
			scheme://multicast-address:port. Optional. In the absence of
			this parameter no multicast address is configured.
			Content-Type: application/link-format
			The following response codes are defined for this interface:
			Success: 2.01 "Created". The Location header MUST be included with
			the new group entry. This Location MUST be a stable identifier
			generated by the RD as it is used for delete operations on this
			registration.
			Failure: 4.00 "Bad Request". Malformed request.
			Failure: 5.03 "Service Unavailable". Service could not perform the
			operation.
			The following example shows a group with the name "lights"
			registering two endpoints to an RD using this interface. The
			resulting location /rd-group/12 is just an example of an RD generated
			group location.
			EP RD
			| |
			| - POST /rd-group?gp=lights "<>;ep=node1..." --> |
			| |
			| |
			| <---- 2.01 Created Location: /rd-group/12 ---- |
			| |
			Req: POST coap://rd.example.com/rd-group?gp=lights
			Payload:
			<>;ep="node1",
			<>;ep="node2"
			Res: 2.01 Created
			Location: /rd-group/12
			6.2. Group Removal
			A group can be removed simply by sending a removal message to the
			location returned when registering the group. Removing a group MUST
			NOT remove the endpoints of the group from the RD.
			The removal request interface is specified as follows:
			Interaction: Manager -> RD
			Method: DELETE
			URI Template: /{+location}
			URI Template Variables:
			location := This is the Location path returned by the RD as a
			result of a successful group registration.
			The following responses codes are defined for this interface:
			Success: 2.02 "Deleted" upon successful deletion
			Failure: 4.00 "Bad Request". Malformed request.
			Failure: 5.03 "Service Unavailable". Service could not perform the
			operation.
			The following examples shows successful removal of the group from the
			RD.
			EP RD
			| |
			| --- DELETE /rd-group/412 -------------------> |
			| |
			| |
			| <-- 2.02 Deleted ---------------------------- |
			| |
			Req: DELETE /rd-group/12
			Res: 2.02 Deleted
			7. RD Lookup Function Set
	In order for an RD to be used for discovering resources registered		In order for an RD to be used for discovering resources registered
	with it, a lookup interface can be provided using this function set.		with it, a lookup interface can be provided using this function set.
	This lookup interface is defined as a default, and it is assumed that		This lookup interface is defined as a default, and it is assumed that
	RDs may also support lookups to return resource descriptions in		RDs may also support lookups to return resource descriptions in
	alternative formats (e.g. Atom or HTML Link) or using more advanced		alternative formats (e.g. Atom or HTML Link) or using more advanced
	interfaces (e.g. supporting context or semantic based lookup).		interfaces (e.g. supporting context or semantic based lookup).
	This function set allows lookups for Domains, endpoints and resources		This function set allows lookups for domains, groups, endpoints and
	using attributes defined in the RD Function Set and for use with the		resources using attributes defined in the RD Function Set and for use
	CoRE Link Format. The result of a lookup request is the list of		with the CoRE Link Format. The result of a lookup request is the
	links (if any) in CoRE Link Format corresponding to the type of		list of links (if any) in CoRE Link Format corresponding to the type
	lookup. The target of these links SHOULD be the actual location of		of lookup. The target of these links SHOULD be the actual location
	the Domain, endpoint or resource, but MAY be an intermediate proxy		of the domain, endpoint or resource, but MAY be an intermediate proxy
	e.g. in the case of an HTTP lookup interface for CoAP endpoints.		e.g. in the case of an HTTP lookup interface for CoAP endpoints.
			Multiple query parameters MAY be included in a lookup, all included
			parameters MUST match for a resource to be returned. The character
			'*' MAY be included at the end of a parameter value as a wildcard
			operator.
	The lookup interface is specified as follows:		The lookup interface is specified as follows:
	Interaction: Client -> RD		Interaction: Client -> RD
	Method: GET		Method: GET
	URI Template: /{+rd-lookup-base}/{lookup-type}{?d,ep,resource-param}		URI Template: /{+rd-lookup-base}/
			{lookup-type}{?d,ep,gp,et,rt,page,count,resource-param}
	Parameters:		Parameters:
	rd-lookup-base := RD Lookup Function Set path (mandatory). This		rd-lookup-base := RD Lookup Function Set path (mandatory). This
	is the path of the RD Lookup Function Set. An RD SHOULD use the		is the path of the RD Lookup Function Set. An RD SHOULD use the
	value "rd-lookup" for this variable whenever possible.		value "rd-lookup" for this variable whenever possible.
	lookup-type := ("d", "ep", "res") (mandatory) This variable is		lookup-type := ("d", "ep", "res", "gp") (mandatory) This
	used to select the kind of lookup to perform (Domain, endpoint		variable is used to select the kind of lookup to perform
	or resource).		(domain, endpoint or resource).
	ep := endpoint (optional). Used for endpoint and resource		ep := Endpoint (optional). Used for endpoint, group and
	lookups.		resource lookups.
	d := Domain (optional). Used for Domain, endpoint and resource		d := Domain (optional). Used for domain, group, endpoint and
	lookups.		resource lookups.
	rt := endpoint type (optional). Used for endpoint lookups.		page := Page (optional). Parameter can not be used without the
			count parameter. Results are returned from result set in pages
			that contains 'count' results starting from index (page *
			count).
			count := Count (optional). Number of results is limited to this
			parameter value. If the parameter is not present, then an RD
			implementation specific default value SHOULD be used.
			rt := Resource type (optional). Used for group, endpoint and
			resource lookups.
			rt := Endpoint type (optional). Used for group, endpoint and
			resource lookups.
	resource-param := Link attribute parameters (optional). Any		resource-param := Link attribute parameters (optional). Any
	link attribute as defined in Section 4.1 of		link attribute as defined in Section 4.1 of [RFC6690], used for
	[I-D.ietf-core-link-format], used for resource lookups.		resource lookups.
	The following responses codes are defined for this interface:		The following responses codes are defined for this interface:
	Success: 2.05 "Content" with an application/link-format payload		Success: 2.05 "Content" with an application/link-format payload
	containing a matching entries for the lookup.		containing a matching entries for the lookup.
	Failure: 4.04 "Not Found" in case no matching entry is found for a		Failure: 4.04 "Not Found" in case no matching entry is found for a
	unicast request.		unicast request.
	Failure: No error response to a multicast request.		Failure: No error response to a multicast request.
	Failure: 4.00 "Bad Request". Malformed request.		Failure: 4.00 "Bad Request". Malformed request.
	Failure: 5.03 "Service Unavailable". Service could not perform the		Failure: 5.03 "Service Unavailable". Service could not perform the
	operation.		operation.
	The following example shows a client performing a resource lookup:		The following example shows a client performing a resource lookup:
	Client RD		Client RD
	| |		| |
	| ----- GET /rd-lookup/res?rt=Temperature -----------------> |		| ----- GET /rd-lookup/res?rt=temperature -----------------> |
	| |		| |
	| |		| |
	| <-- 2.05 Content "<coap://node1/temp>;rt="Temperature" ---- |		| <-- 2.05 Content "<coap://node1/temp>;rt="temperature" ---- |
	| |		| |
	Req: GET /rd-lookup/res?rt=Temperature		Req: GET /rd-lookup/res?rt=temperature
	Res: 2.05 Content		Res: 2.05 Content
	<coap://{ip:port}/temp>;rt="Temperature"		<coap://{ip:port}/temp>
	The following example shows a client performing an endpoint lookup:		The following example shows a client performing an endpoint lookup:
	Client RD		Client RD
	| |		| |
	| ----- GET /rd-lookup/ep?rt=PowerNode --------------------> |		| ----- GET /rd-lookup/ep?et=power-node --------------------> |
	| |		| |
	| |		| |
	| <-- 2.05 Content "<coap://{ip:port}>;ep="node5" ----------- |		| <-- 2.05 Content "<coap://{ip:port}>;ep="node5" ----------- |
	| |		| |
	Req: GET /rd-lookup/ep?rt=PowerNode		Req: GET /rd-lookup/ep?et=power-node
	Res: 2.05 Content		Res: 2.05 Content
	<coap://{ip:port}>;ep="node5"		<coap://{ip:port}>;ep="node5",
	<coap://{ip:port}>;ep="node7"		<coap://{ip:port}>;ep="node7"
	The following example shows a client performing a Domain lookup:		The following example shows a client performing a domain lookup:
	Client RD		Client RD
	| |		| |
	| ----- GET /rd-lookup/domain -----------------------------> |		| ----- GET /rd-lookup/d ----------------------------------> |
	| |		| |
	| |		| |
	| <-- 2.05 Content "</rd>;d=domain1,</rd>;d=domain2 --------- |		| <-- 2.05 Content "</rd>;d=domain1,</rd>;d=domain2 --------- |
	| |		| |
	Req: GET /rd-lookup/domain		Req: GET /rd-lookup/d
	Res: 2.05 Content		Res: 2.05 Content
	</rd>;d=domain1,		</rd>;d="domain1",
	</rd>;d=domain2		</rd>;d="domain2"
	7. New Link-Format Attributes		The following example shows a client performing a group lookup for
			all groups:
			Client RD
			| |
			| ----- GET /rd-lookup/gp ---------------------------------> |
			| |
			| |
			| <-- 2.05 Content </rd-group/12>;gp="lights1";d="domain1" -- |
			| |
			Req: GET /rd-lookup/gp
			Res: 2.05 Content
			</rd-group/12>;gp="lights1";d="domain1"
			The following example shows a client performing a lookup for all
			endpoints in a particular group:
			Client RD
			| |
			| ----- GET GET /rd-lookup/ep?gp=lights1-------------------> |
			| |
			| |
			| <-- 2.05 Content "</rd>;d=domain1,</rd>;d=domain2 --------- |
			| |
			Req: GET /rd-lookup/ep?gp=lights1
			Res: 2.05 Content
			<coap://host:port>;ep="node1",
			<coap://host:port>;ep="node2",
			The following example shows a client performing a lookup for all
			groups an endpoint belongs to:
			Client RD
			| |
			| ----- GET /rd-lookup/gp?ep=node1 ------------------------> |
			| |
			| |
			| <-- 2.05 Content "</rd>;d=domain1,</rd>;d=domain2 --------- |
			| |
			Req: GET /rd-lookup/gp?ep=node1
			Res: 2.05 Content
			<coap://host:port>;gp="lights1";ep="node1",
			8. New Link-Format Attributes
	When using the CoRE Link Format to describe resources being		When using the CoRE Link Format to describe resources being
	discovered by or posted to a resource directory service, additional		discovered by or posted to a resource directory service, additional
	information about those resources is useful. This specification		information about those resources is useful. This specification
	defines the following new attributes for use in the CoRE Link Format		defines the following new attributes for use in the CoRE Link Format
	[I-D.ietf-core-link-format]:		[RFC6690]:
	link-extension = ( "ins" "=" quoted-string ) ; Max 63 bytes		link-extension = ( "ins" "=" quoted-string ) ; Max 63 bytes
	link-extension = ( "exp" )		link-extension = ( "exp" )
	7.1. Resource Instance 'ins' attribute		8.1. Resource Instance 'ins' attribute
	The Resource Instance "ins" attribute is an identifier for this		The Resource Instance "ins" attribute is an identifier for this
	resource, which makes it possible to distinguish from other similar		resource, which makes it possible to distinguish from other similar
	resources. This attribute is similar in use to the "Instance"		resources. This attribute is similar in use to the "Instance"
	portion of a DNS-SD record, and SHOULD be unique across resources		portion of a DNS-SD record, and SHOULD be unique across resources
	with the same Resource Type attribute in the Domain it is used. A		with the same Resource Type attribute in the domain it is used. A
	Resource Instance might be a descriptive string like "Ceiling Light,		Resource Instance might be a descriptive string like "Ceiling Light,
	Room 3", a short ID like "AF39" or a unique UUID or iNumber. This		Room 3", a short ID like "AF39" or a unique UUID or iNumber. This
	attribute is used by a Resource Directory to distinguish between		attribute is used by a Resource Directory to distinguish between
	multiple instances of the same resource type within a system.		multiple instances of the same resource type within a system.
	This attribute MUST be no more than 63 bytes in length. The resource		This attribute MUST be no more than 63 bytes in length. The resource
	identifier attribute MUST NOT appear more than once in a link		identifier attribute MUST NOT appear more than once in a link
	description.		description.
	7.2. Export 'exp' attribute		8.2. Export 'exp' attribute
	The Export "exp" attribute is used as a flag to indicate that a link		The Export "exp" attribute is used as a flag to indicate that a link
	description MAY be exported by a resource directory to external		description MAY be exported by a resource directory to external
	directories.		directories.
	The CoRE Link Format is used for many purposes between CoAP		The CoRE Link Format is used for many purposes between CoAP
	endpoints. Some are useful mainly locally, for example checking the		endpoints. Some are useful mainly locally, for example checking the
	observability of a resource before accessing it, determining the size		observability of a resource before accessing it, determining the size
	of a resource, or traversing dynamic resource structures. However,		of a resource, or traversing dynamic resource structures. However,
	other links are very useful to be exported to other directories, for		other links are very useful to be exported to other directories, for
	example the entry point resource to a functional service.		example the entry point resource to a functional service.
	8. Security Considerations		9. Security Considerations
	This document needs the same security considerations as described in		This document needs the same security considerations as described in
	Section 7 of [RFC5988] and Section 6 of [I-D.ietf-core-link-format].		Section 7 of [RFC5988] and Section 6 of [RFC6690]. The /.well-known/
	The /.well-known/core resource may be protected e.g. using DTLS when		core resource may be protected e.g. using DTLS when hosted on a CoAP
	hosted on a CoAP server as described in [I-D.ietf-core-coap].		server as described in [I-D.ietf-core-coap].
	Access control SHOULD be performed separately for the RD Function Set		Access control SHOULD be performed separately for the RD Function Set
	and the RD Lookup Function Set, as different endpoints may be		and the RD Lookup Function Set, as different endpoints may be
	authorized to register with an RD from those authorized to lookup		authorized to register with an RD from those authorized to lookup
	endpoints from the RD. Such access control SHOULD be performed in as		endpoints from the RD. Such access control SHOULD be performed in as
	fine-grained a level as possible. For example access control for		fine-grained a level as possible. For example access control for
	lookups could be performed either at the Domain, endpoint or resource		lookups could be performed either at the domain, endpoint or resource
	level.		level.
	9. IANA Considerations		10. IANA Considerations
	"core.rd" and "core.rd-lookup" resource type needs to be registered		"core.rd", "core.rd-group" and "core.rd-lookup" resource types need
	when the appropriate registry is created by		to be registered with the resource type registry defined by
	[I-D.ietf-core-link-format].		[RFC6690].
	The "exp" attribute needs to be registered when a future Web Linking		The "exp" attribute needs to be registered when a future Web Linking
	attribute is created.		attribute is created.
	10. Acknowledgments		11. Acknowledgments
	Szymon Sasin, Kerry Lynn, Peter van der Stok, Anders Brandt, Matthieu		Szymon Sasin, Kerry Lynn, Esko Dijk, Peter van der Stok, Anders
	Vial, Sampo Ukkola and Linyi Tian have provided helpful comments,		Brandt, Matthieu Vial, Sampo Ukkola and Linyi Tian have provided
	discussions and ideas to improve and shape this document. The		helpful comments, discussions and ideas to improve and shape this
	authors would also like to thank their collagues from the EU FP7		document. The authors would also like to thank their collagues from
	SENSEI project, where many of the resource directory concepts were		the EU FP7 SENSEI project, where many of the resource directory
	originally developed.		concepts were originally developed.
	11. Changelog		12. Changelog
			Changes from -04 to -05:
			o Restricted Update to parameter updates.
			o Added pagination support for the Lookup interface.
			o Minor editing, bug fixes and reference updates.
			o Added group support.
			o Changed rt= to et= for the registration & update interface
	Changes from -03 to -04:		Changes from -03 to -04:
	o Added the ins= parameter back for the DNS-SD mapping.		o Added the ins= parameter back for the DNS-SD mapping.
	o Integrated the Simple Directory Discovery from Carsten.		o Integrated the Simple Directory Discovery from Carsten.
	o Editorial improvements.		o Editorial improvements.
	o Fixed the use of ETags.		o Fixed the use of ETags.
	skipping to change at page 21, line 12 ¶		skipping to change at page 25, line 49 ¶
	o Added the concept of an RD Domain and a registration parameter		o Added the concept of an RD Domain and a registration parameter
	for it.		for it.
	o Recommended the Location returned from a registration to be		o Recommended the Location returned from a registration to be
	stable, allowing for endpoint and Domain information to be changed		stable, allowing for endpoint and Domain information to be changed
	during updates.		during updates.
	o Changed the lookup interface to accept endpoint and Domain as		o Changed the lookup interface to accept endpoint and Domain as
	query string parameters to control the scope of a lookup.		query string parameters to control the scope of a lookup.
	12. References		13. References
			13.1. Normative References
	12.1. Normative References
	[I-D.ietf-core-link-format]
	Shelby, Z., "CoRE Link Format",
	draft-ietf-core-link-format-14 (work in progress),
	June 2012.
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119, March 1997.		Requirement Levels", BCP 14, RFC 2119, March 1997.
	[RFC5988] Nottingham, M., "Web Linking", RFC 5988, October 2010.		[RFC5988] Nottingham, M., "Web Linking", RFC 5988, October 2010.
	[RFC6570] Gregorio, J., Fielding, R., Hadley, M., Nottingham, M.,		[RFC6570] Gregorio, J., Fielding, R., Hadley, M., Nottingham, M.,
	and D. Orchard, "URI Template", RFC 6570, March 2012.		and D. Orchard, "URI Template", RFC 6570, March 2012.
	12.2. Informative References		[RFC6690] Shelby, Z., "Constrained RESTful Environments (CoRE) Link
			Format", RFC 6690, August 2012.
			13.2. Informative References
	[I-D.brandt-coap-subnet-discovery]		[I-D.brandt-coap-subnet-discovery]
	Brandt, A., "Discovery of CoAP servers across subnets",		Brandt, A., "Discovery of CoAP servers across subnets",
	draft-brandt-coap-subnet-discovery-00 (work in progress),		draft-brandt-coap-subnet-discovery-00 (work in progress),
	March 2011.		March 2011.
	[I-D.ietf-6lowpan-nd]
	Shelby, Z., Chakrabarti, S., and E. Nordmark, "Neighbor
	Discovery Optimization for Low Power and Lossy Networks
	(6LoWPAN)", draft-ietf-6lowpan-nd-18 (work in progress),
	October 2011.
	[I-D.ietf-core-coap]		[I-D.ietf-core-coap]
	Shelby, Z., Hartke, K., Bormann, C., and B. Frank,		Shelby, Z., Hartke, K., Bormann, C., and B. Frank,
	"Constrained Application Protocol (CoAP)",		"Constrained Application Protocol (CoAP)",
	draft-ietf-core-coap-10 (work in progress), June 2012.		draft-ietf-core-coap-13 (work in progress), December 2012.
	[I-D.vanderstok-core-bc]		[I-D.vanderstok-core-bc]
	Stok, P. and K. Lynn, "CoAP Utilization for Building		Stok, P. and K. Lynn, "CoAP Utilization for Building
	Control", draft-vanderstok-core-bc-05 (work in progress),		Control", draft-vanderstok-core-bc-05 (work in progress),
	October 2011.		October 2011.
	[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,		[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
	Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext		Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
	Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.		Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
			[RFC6775] Shelby, Z., Chakrabarti, S., Nordmark, E., and C. Bormann,
			"Neighbor Discovery Optimization for IPv6 over Low-Power
			Wireless Personal Area Networks (6LoWPANs)", RFC 6775,
			November 2012.
	Authors' Addresses		Authors' Addresses
	Zach Shelby		Zach Shelby
	Sensinode		Sensinode
	Kidekuja 2		Kidekuja 2
	Vuokatti 88600		Vuokatti 88600
	FINLAND		FINLAND
	Phone: +358407796297		Phone: +358407796297
	Email: zach@sensinode.com		Email: zach@sensinode.com
End of changes. 75 change blocks.
	151 lines changed or deleted		360 lines changed or added
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