draft-ietf-core-interfaces-10.txt   draft-ietf-core-interfaces-11.txt 
CoRE Working Group Z. Shelby CoRE Working Group Z. Shelby
Internet-Draft ARM Internet-Draft ARM
Intended status: Informational M. Vial Intended status: Informational M. Vial
Expires: March 18, 2018 Schneider-Electric Expires: September 6, 2018 Schneider-Electric
M. Koster M. Koster
SmartThings SmartThings
C. Groves C. Groves
J. Zhu J. Zhu
Huawei Huawei
B. Silverajan, Ed. B. Silverajan, Ed.
Tampere University of Technology Tampere University of Technology
September 14, 2017 March 05, 2018
Reusable Interface Definitions for Constrained RESTful Environments Reusable Interface Definitions for Constrained RESTful Environments
draft-ietf-core-interfaces-10 draft-ietf-core-interfaces-11
Abstract Abstract
This document defines a set of Constrained RESTful Environments This document defines a set of Constrained RESTful Environments
(CoRE) Link Format Interface Descriptions [RFC6690] applicable for (CoRE) Link Format Interface Descriptions [RFC6690] applicable for
use in constrained environments. These include the: Actuator, use in constrained environments. These include the: Actuator,
Parameter, Read-only parameter, Sensor, Batch, Linked Batch and Link Parameter, Read-only parameter, Sensor, Batch, Linked Batch and Link
List interfaces. List interfaces.
The Batch, Linked Batch and Link List interfaces make use of resource The Batch, Linked Batch and Link List interfaces make use of resource
collections. This document further describes how collections relate collections. This document further describes how collections relate
to interfaces. to interfaces.
Many applications require a set of interface descriptions in order Many applications require a set of interface descriptions in order
provide the required functionality. This document defines the provide the required functionality. This document defines an
concept of function sets to specify this set of interfaces and Interface Description atribute value to describe resources conforming
resources. to a particular interface.
Editor's notes: Editor's notes:
o The git repository for the draft is found at https://github.com/ o The git repository for the draft is found at https://github.com/
core-wg/interfaces core-wg/interfaces
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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 https://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 March 18, 2018. This Internet-Draft will expire on September 6, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Collections . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. Collections . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Introduction to Collections . . . . . . . . . . . . . . . 5 3.1. Introduction to Collections . . . . . . . . . . . . . . . 5
3.2. Use Cases for Collections . . . . . . . . . . . . . . . . 6 3.2. Use Cases for Collections . . . . . . . . . . . . . . . . 5
3.3. Content-Formats for Collections . . . . . . . . . . . . . 6 3.3. Content-Formats for Collections . . . . . . . . . . . . . 6
3.4. Links and Items in Collections . . . . . . . . . . . . . 7 3.4. Link Embedding . . . . . . . . . . . . . . . . . . . . . 6
3.5. Queries on Collections . . . . . . . . . . . . . . . . . 8 3.5. Links and Items in Collections . . . . . . . . . . . . . 7
3.6. Observing Collections . . . . . . . . . . . . . . . . . . 8 3.6. Queries on Collections . . . . . . . . . . . . . . . . . 8
3.7. Collection Types . . . . . . . . . . . . . . . . . . . . 8 3.7. Observing Collections . . . . . . . . . . . . . . . . . . 8
3.8. Collection Types . . . . . . . . . . . . . . . . . . . . 8
4. Interface Descriptions . . . . . . . . . . . . . . . . . . . 9 4. Interface Descriptions . . . . . . . . . . . . . . . . . . . 9
4.1. Link List . . . . . . . . . . . . . . . . . . . . . . . . 11 4.1. Link List . . . . . . . . . . . . . . . . . . . . . . . . 11
4.2. Batch . . . . . . . . . . . . . . . . . . . . . . . . . . 11 4.2. Batch . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.3. Linked Batch . . . . . . . . . . . . . . . . . . . . . . 12 4.3. Linked Batch . . . . . . . . . . . . . . . . . . . . . . 12
4.4. Sensor . . . . . . . . . . . . . . . . . . . . . . . . . 13 4.4. Sensor . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.5. Parameter . . . . . . . . . . . . . . . . . . . . . . . . 14 4.5. Parameter . . . . . . . . . . . . . . . . . . . . . . . . 14
4.6. Read-only Parameter . . . . . . . . . . . . . . . . . . . 14 4.6. Read-only Parameter . . . . . . . . . . . . . . . . . . . 14
4.7. Actuator . . . . . . . . . . . . . . . . . . . . . . . . 14 4.7. Actuator . . . . . . . . . . . . . . . . . . . . . . . . 14
5. Security Considerations . . . . . . . . . . . . . . . . . . . 15 5. Security Considerations . . . . . . . . . . . . . . . . . . . 15
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
skipping to change at page 3, line 15 skipping to change at page 3, line 16
6.3. Linked Batch . . . . . . . . . . . . . . . . . . . . . . 16 6.3. Linked Batch . . . . . . . . . . . . . . . . . . . . . . 16
6.4. Sensor . . . . . . . . . . . . . . . . . . . . . . . . . 16 6.4. Sensor . . . . . . . . . . . . . . . . . . . . . . . . . 16
6.5. Parameter . . . . . . . . . . . . . . . . . . . . . . . . 16 6.5. Parameter . . . . . . . . . . . . . . . . . . . . . . . . 16
6.6. Read-only parameter . . . . . . . . . . . . . . . . . . . 17 6.6. Read-only parameter . . . . . . . . . . . . . . . . . . . 17
6.7. Actuator . . . . . . . . . . . . . . . . . . . . . . . . 17 6.7. Actuator . . . . . . . . . . . . . . . . . . . . . . . . 17
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 17 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 17
8. Changelog . . . . . . . . . . . . . . . . . . . . . . . . . . 18 8. Changelog . . . . . . . . . . . . . . . . . . . . . . . . . . 18
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 21 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 21
9.1. Normative References . . . . . . . . . . . . . . . . . . 21 9.1. Normative References . . . . . . . . . . . . . . . . . . 21
9.2. Informative References . . . . . . . . . . . . . . . . . 21 9.2. Informative References . . . . . . . . . . . . . . . . . 21
Appendix A. Current Usage of Interfaces and Function Sets . . . 22 Appendix A. Current Usage of Interfaces and Function Sets . . . 23
A.1. Constrained RESTful Environments (CoRE) Link Format A.1. Constrained RESTful Environments (CoRE) Link Format
(IETF) . . . . . . . . . . . . . . . . . . . . . . . . . 23 (IETF) . . . . . . . . . . . . . . . . . . . . . . . . . 23
A.2. CoRE Resource Directory (IETF) . . . . . . . . . . . . . 23 A.2. CoRE Resource Directory (IETF) . . . . . . . . . . . . . 23
A.3. Open Connectivity Foundation (OCF) . . . . . . . . . . . 23 A.3. Open Connectivity Foundation (OCF) . . . . . . . . . . . 23
A.4. oneM2M . . . . . . . . . . . . . . . . . . . . . . . . . 24 A.4. oneM2M . . . . . . . . . . . . . . . . . . . . . . . . . 24
A.5. OMA LWM2M . . . . . . . . . . . . . . . . . . . . . . . . 24 A.5. OMA LWM2M . . . . . . . . . . . . . . . . . . . . . . . . 25
Appendix B. Resource Profile example . . . . . . . . . . . . . . 25 Appendix B. Resource Profile example . . . . . . . . . . . . . . 25
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 26 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 26
1. Introduction 1. Introduction
IETF Standards for machine to machine communication in constrained IETF Standards for machine to machine communication in constrained
environments describe a REST protocol and a set of related environments describe a REST protocol and a set of related
information standards that may be used to represent machine data and information standards that may be used to represent machine data and
machine metadata in REST interfaces. CoRE Link-format is a standard machine metadata in REST interfaces. CoRE Link-format is a standard
for doing Web Linking [RFC5988] in constrained environments. SenML for doing Web Linking [RFC8288] in constrained environments. SenML
[I-D.ietf-core-senml] is a simple data model and representation [I-D.ietf-core-senml] is a simple data model and representation
format for composite and complex structured resources. CoRE Link- format for composite and complex structured resources. CoRE Link-
Format and SenML can be used by CoAP [RFC7252] or HTTP servers. Format and SenML can be used by CoAP [RFC7252] or HTTP servers.
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. Machine application clients must be able to humans in the loop. Machine application clients must be able to
adapt to different resource organizations without advance knowledge adapt to different resource organizations without advance knowledge
of the specific data structures hosted by each connected thing. The of the specific data structures hosted by each connected thing. The
use of Web Linking for the description and discovery of resources use of Web Linking for the description and discovery of resources
hosted by constrained web servers is specified by CoRE Link Format hosted by constrained origin servers is specified by CoRE Link Format
[RFC6690]. CoRE Link Format additionally defines a link attribute [RFC6690]. CoRE Link Format additionally defines a link attribute
for interface description ("if") that can be used to describe the for interface description ("if") that can be used to describe the
REST interface of a resource, and may include a link to a description REST interface of a resource, and may include a link to a description
document. document.
This document defines a set of Link Format interface descriptions for This document defines a set of Link Format interface descriptions for
some common design patterns that enable the server side composition some common design patterns that enable the server side composition
and organization, and client side discovery and consumption, of and organization, and client side discovery and consumption, of
machine resources using Web Linking. A client discovering the "if" machine resources using Web Linking. A client discovering the "if"
link attribute will be able to consume resources based on its link attribute will be able to consume resources based on its
skipping to change at page 4, line 34 skipping to change at page 4, line 35
interfaces described can also be realized using HTTP [RFC7230]. interfaces described can also be realized using HTTP [RFC7230].
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", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
[RFC2119]. [RFC2119].
This document requires readers to be familiar with all the terms and This document requires readers to be familiar with all the terms and
concepts that are discussed in [RFC5988] and [RFC6690]. This concepts that are discussed in [RFC8288] and [RFC6690]. This
document makes use of the following additional terminology: document makes use of the following additional terminology:
Gradual Reveal: A REST design where resources are discovered Gradual Reveal: A REST design where resources are discovered
progressively using Web Linking. progressively using Web Linking.
Interface Description: The Interface Description describes the Interface Description: The Interface Description describes the
generic REST interface to interact with a resource or a set of generic REST interface to interact with a resource or a set of
resources. Its use is described via the Interface Description resources. Its use is described via the Interface Description
'if' attribute which is an opaque string used to provide a name or 'if' attribute which is an opaque string used to provide a name or
URI indicating a specific interface definition used to interact URI indicating a specific interface definition used to interact
with the target resource. One can think of this as describing with the target resource. One can think of this as describing
verbs usable on a resource. verbs usable on a resource.
Resource Discovery: The process allowing a web client to identify Resource Discovery: The process allowing a client to identify
resources being hosted on a web server. resources being hosted on an origin server.
Service Discovery: The process making it possible for a web client
to automatically detect devices and Function Sets offered by these
devices on a CoRE network.
3. Collections 3. Collections
3.1. Introduction to Collections 3.1. Introduction to Collections
A Collection is a resource which represents one or more related A Collection is a resource which represents one or more related
resources. [RFC6573] describes the "item" and "collection" Link resources. [RFC6573] describes the "item" and "collection" Link
Relation. "item" link relation identifies a member of collection. Relation. An "item" link relation identifies a member of collection.
"collection" indicates the collection that an item is a member of. A "collection" indicates the collection that an item is a member of.
For example: A collection might be a resource representing catalog of For example, a collection might be a resource representing a catalog
products, an item is a resource related to an individual product. of products, while an item is a resource related to an individual
product.
Section 1.2.2/[RFC6690] also describes resource collections. Section 1.2.2/[RFC6690] also describes resource collections.
This document uses the concept of "collection" and applies it to This document uses the concept of "collection" and applies it to
interface descriptions. A collection interface description consists interface descriptions. A collection interface description consists
of a set of links and a set of items pointed to by the links which of a set of links and a set of items pointed to by the links which
may be sub-resources of the collection resource. The collection may be sub-resources of the collection resource. The collection
interface descriptions described in this document are Link List, interface descriptions described in this document are Link List,
Batch and Linked Batch. Batch and Linked Batch.
skipping to change at page 5, line 44 skipping to change at page 5, line 41
A particular resource item may be a member of more than one A particular resource item may be a member of more than one
collection at a time by being linked to, but may only be a collection at a time by being linked to, but may only be a
subresource of one collection. subresource of one collection.
Some collections may have pre-configured items and links, and some Some collections may have pre-configured items and links, and some
collections may support dynamic creation and removal of items and collections may support dynamic creation and removal of items and
links. Likewise, modification of items in some collections may be links. Likewise, modification of items in some collections may be
permitted, and not in others. permitted, and not in others.
Collections may support link embedding, which is analogous to an
image tag (link) causing the image to display inline in a browser
window. Resources pointed to by embedded links in collections may be
interacted with using bulk operations on the collection resource.
For example, performing a GET on a collection resource may return a
single representation containing all of the linked resources.
Links in collections may be selected for processing by a particular Links in collections may be selected for processing by a particular
request by using Query Filtering as described in CoRE Link-Format request by using Query Filtering as described in CoRE Link-Format
[RFC6690]. [RFC6690].
3.2. Use Cases for Collections 3.2. Use Cases for Collections
Collections may be used to provide gradual reveal of resources on an Collections may be used to provide gradual reveal of resources on an
endpoint. There may be a small set of links at the .well-known/core endpoint. There may be a small set of links at the .well-known/core
location, which may in turn point to other collections of resources location, which may in turn point to other collections of resources
that represent device information, device configuration, device that represent device information, device configuration, device
management, and various functional clusters of resources on the management, and various functional clusters of resources on the
device. device.
A collection may provide resource encapsulation, where link embedding
may be used to provide a single resource with which a client may
interact to obtain a set of related resource values. For example, a
collection for manufacturer parameters may consist of manufacturer
name, date of manufacture, location of manufacture, and serial number
resources which can be read as a single senml data object.
A collection may be used to group a set of like resources for bulk A collection may be used to group a set of like resources for bulk
state update or actuation. For example, the brightness control state update or actuation. For example, the brightness control
resources of a number of luminaries may be grouped by linking to them resources of a number of luminaries may be grouped by linking to them
in a collection. The collection type may support receiving a single in a collection. The collection type may support receiving a single
update form a client and sending that update to each resource item in update from a client and sending that update to each resource item in
the collection. the collection.
Items may be sub-resources of the collection resource. This enables Items may be sub-resources of the collection resource. This enables
updates to multiple items in the collection to be processed together updates to multiple items in the collection to be processed together
within the context of the collection resource. within the context of the collection resource.
3.3. Content-Formats for Collections 3.3. Content-Formats for Collections
The collection interfaces by default use CoRE Link-Format for the The collection interfaces by default use CoRE Link-Format for the
link representations and SenML or text/plain for representations of link representations and SenML or text/plain for representations of
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by the Content-Format option in the header of the update request by the Content-Format option in the header of the update request
operation. operation.
The default Content-Formats for collection types described in this The default Content-Formats for collection types described in this
document are: document are:
Links: application/link-format, application/link-format+json Links: application/link-format, application/link-format+json
Items: application/senml+json, text/plain Items: application/senml+json, text/plain
3.4. Links and Items in Collections 3.4. Link Embedding
Collections may provide resource encapsulation by supporting link
embedding. Link embedding may be used to provide a single resource
with which a client may interact to obtain a set of related resource
values. This is analogous to an image tag (link) causing the image
to display inline in a browser window. Link embedding enables the
bulk processing of items in the collection using a single operation
targeting the collection resource. Performing a GET on a collection
resource may return a single representation containing all of the
embedded linked resources. For example, a collection for
manufacturer parameters may consist of manufacturer name, date of
manufacture, location of manufacture, and serial number resources
which can be read as a single senml data object.
A subset of resources in the collection may be selected for operation
using Query Filtering. Bulk Read operations using GET return a SenML
representation of all selected resources. Bulk item Update
operations using PUT or POST apply the payload document to all
selected resource items in the collection, using either a Batch or
Group update policy. A Batch update is performed by applying the
resource values in the payload document to all resources in the
collection that match any resource name in the payload document.
Group updates are performed by applying the payload document to each
item in the collection. Group updates are indicated by the link
relation type rel="grp" in the link.
3.5. Links and Items in Collections
Links use CoRE Link-Format representation by default and may point to Links use CoRE Link-Format representation by default and may point to
any resource reachable from the context of the collection. This any resource reachable from the context of the collection. This
includes absolute links and links that point to other network includes links to resources with absolute paths as well as links that
locations if the context of the collection allows. Links to sub- point to other network locations, if the context of the collection
resources in the collection MUST have a path-element starting with allows. Links to sub-resources in the collection MUST have a path-
the resource name, as per [RFC3986]. Links to resources in the element starting with the resource name, as per [RFC3986]. Links to
global context MUST start with a root path identifier [RFC5988]. resources in the global context MUST start with a root path
Links to other collections are formed per [RFC3986]. identifier [RFC8288]. Links to other collections are formed per
[RFC3986].
Examples of links: Examples of links:
</sen/>;if="core.lb"': Link to the /sen/ collection describing it as </sen/>;if="core.lb": Link to the /sen/ collection describing it as
a core.lb type collection (Linked Batch) a core.lb type collection (Linked Batch)
</sen/>;rel="grp"': Link to the /sen/ collection indicating that </sen/>;rel="grp": Link to the /sen/ collection indicating that
/sen/ is a member of a group in the collection in which the link /sen/ is a member of a group in the collection in which the link
appears. appears.
<"/sen/temp">;rt="temperature"': An absolute link to the resource at </sen/temp>;rt="temperature": A link to the temp resource with an
the path /sen/temp absolute path.
<temp>;rt="temperature": Link to the temp subresource of the <temp>;rt="temperature": Link to the temp subresource of the
collection in which this link appears." collection in which this link appears.
<temp>;anchor="/sen/": A link to the temp subresource of the <temp>;anchor="/sen/": A link to the temp subresource of the
collection /sen/ which is assumed not to be a subresource of the collection /sen/ which is assumed not to be a subresource of the
collection in which the link appears ,but is expected to be collection in which the link appears, but is expected to be
identified in the collection by resource name. identified in the collection by resource name.
Links in the collection MAY be Read, Updated, Added, or Removed using Links in the collection MAY be Read, Updated, Added, or Removed using
the CoRE Link-Format or JSON Merge-Patch Content-Formats on the the CoRE Link-Format or JSON Merge-Patch Content-Formats on the
collection resource. Reading links uses the GET method and returns collection resource. Reading links uses the GET method and returns
an array or list containing the link-values of all selected links. an array or list containing the link-values of all selected links.
Links may be added to the collection using POST or PATCH methods. Links may be added to the collection using POST or PATCH methods.
Updates to links MUST use the PATCH method and MAY use query Updates to links MUST use the PATCH method and MAY use query
filtering to select links for updating. The PATCH method on links filtering to select links for updating. The PATCH method on links
MUST use the JSON Merge-Patch Content-Format (application/merge- MUST use the JSON Merge-Patch Content-Format (application/merge-
patch+json) specified in [RFC7396]. patch+json) specified in [RFC7396].
Items in the collection SHOULD be represented using the SenML Items in the collection SHOULD be represented using the SenML
(application/senml+json) or plain text (text/plain) Content-Formats, (application/senml+json) or plain text (text/plain) Content-Formats,
depending on whether the representation is of a single data point or depending on whether the representation is of a single data point or
multiple data points. Items MAY be represented using any supported multiple data points. Items MAY be represented using any supported
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filtering to select links for updating. The PATCH method on links filtering to select links for updating. The PATCH method on links
MUST use the JSON Merge-Patch Content-Format (application/merge- MUST use the JSON Merge-Patch Content-Format (application/merge-
patch+json) specified in [RFC7396]. patch+json) specified in [RFC7396].
Items in the collection SHOULD be represented using the SenML Items in the collection SHOULD be represented using the SenML
(application/senml+json) or plain text (text/plain) Content-Formats, (application/senml+json) or plain text (text/plain) Content-Formats,
depending on whether the representation is of a single data point or depending on whether the representation is of a single data point or
multiple data points. Items MAY be represented using any supported multiple data points. Items MAY be represented using any supported
Content-Format. Content-Format.
Link Embedding enables the bulk processing of items in the collection 3.6. Queries on Collections
using a single operation targeting the collection resource. A subset
of resources in the collection may be selected for operation using
Query Filtering. Bulk Read operations using GET return a SenML
representation of all selected resources. Bulk item Update
operations using PUT or POST apply the payload document to all
selected resource items in the collection, using either a Batch or
Group update policy. A Batch update is performed by applying the
resource values in the payload document to all resources in the
collection that match any resource name in the payload document.
Group updates are performed by applying the payload document to each
item in the collection. Group updates are indicated by the link
relation type rel="grp" in the link.
3.5. Queries on Collections
Collections MAY support query filtering as defined in CoRE Link- Collections MAY support query filtering as defined in CoRE Link-
Format [RFC6690]. Operations targeting either the links or the items Format [RFC6690]. Operations targeting either the links or the items
MAY select a subset of links and items in the collection by using MAY select a subset of links and items in the collection by using
query filtering. The Content-Format specified in the request header query filtering. The Content-Format specified in the request header
selects whether links or items are targeted by the operation. selects whether links or items are targeted by the operation.
3.6. Observing Collections 3.7. Observing Collections
Resource Observation via [I-D.ietf-core-dynlink] using CoAP [RFC7252] Resource Observation via [I-D.ietf-core-dynlink] using CoAP [RFC7252]
MAY be supported on items in a collection. A subset of the MAY be supported on items in a collection. A subset of the
conditional observe parameters MAY be specified to apply. In most conditional observe parameters MAY be specified to apply. In most
cases pmin and pmax are useful. Resource observation on a cases pmin and pmax are useful. Resource observation on a
collection's items resource returns the collection representation. collection's resource returns the collection representation.
Observation Responses, or notifications, SHOULD provide the Observation Responses, or notifications, SHOULD provide the
collection representations in SenML Content-Format. Notifications collection representations in SenML Content-Format. Notifications
MAY include multiple observations of the collection resource, with MAY include multiple observations of the collection resource, with
SenML time stamps indicating the observation times. SenML time stamps indicating the observation times.
3.7. Collection Types 3.8. Collection Types
There are three collection types defined in this document: There are three collection types defined in this document:
+-----------------+---------+--------------------+ +-----------------+---------+--------------------+
| Collection Type | if= | Content-Format | | Collection Type | if= | Content-Format |
+-----------------+---------+--------------------+ +-----------------+---------+--------------------+
| Link List | core.ll | link-format | | Link List | core.ll | link-format |
| | | | | | | |
| Batch | core.b | link-format, senml | | Batch | core.b | link-format, senml |
| | | | | | | |
| Linked Batch | core.lb | link-format, senml | | Linked Batch | core.lb | link-format, senml |
+-----------------+---------+--------------------+ +-----------------+---------+--------------------+
Table 1: Collection Type Summary Table 1: Collection Type Summary
The interface description defined in this document describes the The interface description defined in this document offer a deeper
methods and functions that may be applied to the collections. explanation of the methods and functions that may be applied to the
three collections.
4. Interface Descriptions 4. Interface Descriptions
This section defines REST interfaces for Link List, Batch, Sensor, This section defines REST interfaces for Sensor, Parameter, Read-Only
Parameter and Actuator resources. Variants such as Linked Batch or Paramter and Actuator resource types, in addition to the Link List,
Read-Only Parameter are also presented. Each type is described along Batch and Linked Batch collection types. Each type is described
with its Interface Description attribute value and valid methods. along with its Interface Description attribute value, valid methods
These are defined for each interface in the table below. These and content formats. These are shown for each interface in the table
interfaces can support plain text and/or SenML Media types. below.
The if= column defines the Interface Description (if=) attribute The if= column defines the Interface Description (if=) attribute
value to be used in the CoRE Link Format for a resource conforming to value to be used in the CoRE Link Format for a resource conforming to
that interface. When this value appears in the if= attribute of a that interface. When this value appears in the if= attribute of a
link, the resource MUST support the corresponding REST interface link, the resource MUST support the corresponding REST interface
described in this section. The resource MAY support additional described in this section. The resource MAY support additional
functionality, which is out of scope for this document. Although functionality, which is out of scope for this document. Although
these interface descriptions are intended to be used with the CoRE these interface descriptions are intended to be used with the CoRE
Link Format, they are applicable for use in any REST interface Link Format, they are applicable for use in any REST interface
definition. definition.
skipping to change at page 11, line 8 skipping to change at page 11, line 8
</a/1/led>;rt="simple.act.led";if="core.a", </a/1/led>;rt="simple.act.led";if="core.a",
</a/2/led>;rt="simple.act.led";if="core.a", </a/2/led>;rt="simple.act.led";if="core.a",
</d/>;rt="simple.dev";if="core.ll", </d/>;rt="simple.dev";if="core.ll",
</l/>;if="core.lb", </l/>;if="core.lb",
Figure 1: Binding Interface Example Figure 1: Binding Interface Example
4.1. Link List 4.1. Link List
The Link List interface is used to retrieve (GET) a list of resources The Link List interface is used to retrieve (GET) a list of resources
on a web server. The GET request SHOULD contain an Accept option on an origin server. The GET request SHOULD contain an Accept option
with the application/link-format content format. However if the with the application/link-format content format. However if the
resource does not support any other form of content-format the Accept resource does not support any other form of content-format the Accept
option MAY be elided. option MAY be elided.
Note: The use of an Accept option with application/link-format is Note: The use of an Accept option with application/link-format is
recommended even though it is not strictly needed for the link list recommended even though it is not strictly needed for the link list
interface because this interface is extended by the batch and linked interface because this interface is extended by the batch and linked
batch interfaces where different content-formats are possible. batch interfaces where different content-formats are possible.
The request returns a list of URI references with absolute paths to The request returns a list of URI references with absolute paths to
the resources as defined in CoRE Link Format. This interface is the resources as defined in CoRE Link Format. This interface is
typically used with a parent resource to enumerate sub-resources but typically used with a parent resource to enumerate sub-resources but
may be used to reference any resource on a web server. may be used to reference any resource on an origin server.
Link List is the base interface to provide gradual reveal of Link List is the base interface to provide gradual reveal of
resources on a CoRE web server, hence the root resource of a Function resources on a CoRE origin server. Hence the root resource of a
Set SHOULD implement this interface or an extension of this Function Set SHOULD implement this interface or an extension of this
interface. interface.
The following example interacts with a Link List /d containing The following example interacts with a Link List /d containing
Parameter sub-resources /d/name, /d/model. Parameter sub-resources /d/name, /d/model.
Req: GET /d/ (Accept:application/link-format) Req: GET /d/ (Accept:application/link-format)
Res: 2.05 Content (application/link-format) Res: 2.05 Content (application/link-format)
</d/name>;rt="simple.dev.n";if="core.p", </d/name>;rt="simple.dev.n";if="core.p",
</d/model>;rt="simple.dev.mdl";if="core.rp" </d/model>;rt="simple.dev.mdl";if="core.rp"
4.2. Batch 4.2. Batch
The Batch interface is used to manipulate a collection of sub- The Batch interface is used to manipulate a collection of sub-
resources at the same time. The Batch interface description supports resources at the same time. The Batch interface description supports
the same methods as its sub-resources, and can be used to read (GET), the same methods as its sub-resources, and can be used to read (GET),
update (PUT) or apply (POST) the values of those sub-resource with a update (PUT) or apply (POST) the values of those sub-resource with a
single resource representation. The sub-resources of a Batch MAY be single resource representation. The sub-resources of a Batch MAY be
heterogeneous, a method used on the Batch only applies to sub- heterogeneous. Hence, a method used on the Batch only applies to
resources that support it. For example Sensor interfaces do not sub-resources that support it. For example Sensor interfaces do not
support PUT, and thus a PUT request to a Sensor member of that Batch support PUT, and thus a PUT request to a Sensor member of that Batch
would be ignored. A batch requires the use of SenML Media types in would be ignored. A batch requires the use of SenML Media types in
order to support multiple sub-resources. order to support multiple sub-resources.
In addition, the Batch interface is an extension of the Link List In addition, the Batch interface is an extension of the Link List
interface and in consequence MUST support the same methods. For interface and in consequence MUST support the same methods. For
example: a GET with an Accept:application/link-format on a resource example, a GET with an Accept:application/link-format on a resource
utilizing the batch interface will return the sub-resource links. utilizing the batch interface will return the sub-resource links.
The following example interacts with a Batch /s/ with Sensor sub- The following example interacts with a Batch /s/ with Sensor sub-
resources /s/light, /s/temp and /s/humidity. resources /s/light, /s/temp and /s/humidity.
Req: GET /s/ Req: GET /s/
Res: 2.05 Content (application/senml+json) Res: 2.05 Content (application/senml+json)
{"e":[ {"e":[
{ "n": "light", "v": 123, "u": "lx" }, { "n": "light", "v": 123, "u": "lx" },
{ "n": "temp", "v": 27.2, "u": "degC" }, { "n": "temp", "v": 27.2, "u": "degC" },
{ "n": "humidity", "v": 80, "u": "%RH" }], { "n": "humidity", "v": 80, "u": "%RH" }],
} }
4.3. Linked Batch 4.3. Linked Batch
The Linked Batch interface is an extension of the Batch interface. The Linked Batch interface is an extension of the Batch interface.
Contrary to the basic Batch which is a collection statically defined Contrary to the basic Batch which is a collection statically defined
by the web server, a Linked Batch is dynamically controlled by a web by the origin server, a Linked Batch is dynamically controlled by a
client. A Linked Batch resource has no sub-resources. Instead the client. A Linked Batch resource has no sub-resources. Instead the
resources forming the batch are referenced using Web Linking resources forming the batch are referenced using Web Linking
[RFC5988] and the CoRE Link Format [RFC6690]. A request with a POST [RFC8288] and the CoRE Link Format [RFC6690]. A request with a POST
method and a content format of application/link-format simply appends method and a content format of application/link-format simply appends
new resource links to the collection. The links in the payload MUST new resource links to the collection. The links in the payload MUST
reference a resource on the web server with an absolute path. A reference a resource on the origin server with an absolute path. A
DELETE request removes the entire collection. All other requests DELETE request removes the entire collection. All other requests
available for a basic Batch are still valid for a Linked Batch. available for a basic Batch are still valid for a Linked Batch.
The following example interacts with a Linked Batch /l/ and creates a The following example interacts with a Linked Batch /l/ and creates a
collection containing /s/light, /s/temp and /s/humidity in 2 steps. collection containing /s/light, /s/temp and /s/humidity in 2 steps.
Req: POST /l/ (Content-Format: application/link-format) Req: POST /l/ (Content-Format: application/link-format)
</s/light>,</s/temp> </s/light>,</s/temp>
Res: 2.04 Changed Res: 2.04 Changed
skipping to change at page 15, line 49 skipping to change at page 15, line 49
6. IANA Considerations 6. IANA Considerations
This document registers the following CoRE Interface Description This document registers the following CoRE Interface Description
(if=) Link Target Attribute Values. (if=) Link Target Attribute Values.
6.1. Link List 6.1. Link List
Attribute Value: core.ll Attribute Value: core.ll
Description: The Link List interface is used to retrieve a list of Description: The Link List interface is used to retrieve a list of
resources on a web server. resources on an origin server.
Reference: This document. Note to RFC Editor - please insert the Reference: This document. Note to RFC Editor - please insert the
appropriate RFC reference. appropriate RFC reference.
Notes: None Notes: None
6.2. Batch 6.2. Batch
Attribute Value: core.b Attribute Value: core.b
skipping to change at page 16, line 28 skipping to change at page 16, line 28
appropriate RFC reference. appropriate RFC reference.
Notes: None Notes: None
6.3. Linked Batch 6.3. Linked Batch
Attribute Value: core.lb Attribute Value: core.lb
Description: The Linked Batch interface is an extension of the Batch Description: The Linked Batch interface is an extension of the Batch
interface. Contrary to the basic Batch which is a collection interface. Contrary to the basic Batch which is a collection
statically defined by the web server, a Linked Batch is statically defined by the origin server, a Linked Batch is
dynamically controlled by a web client. dynamically controlled by a client.
Reference: This document. Note to RFC Editor - please insert the Reference: This document. Note to RFC Editor - please insert the
appropriate RFC reference. appropriate RFC reference.
Notes: None Notes: None
6.4. Sensor 6.4. Sensor
Attribute Value: core.s Attribute Value: core.s
skipping to change at page 18, line 7 skipping to change at page 18, line 7
Acknowledgement is given to colleagues from the SENSEI project who Acknowledgement is given to colleagues from the SENSEI project who
were critical in the initial development of the well-known REST were critical in the initial development of the well-known REST
interface concept, to members of the IPSO Alliance where further interface concept, to members of the IPSO Alliance where further
requirements for interface descriptions have been discussed, and to requirements for interface descriptions have been discussed, and to
Szymon Sasin, Cedric Chauvenet, Daniel Gavelle and Carsten Bormann Szymon Sasin, Cedric Chauvenet, Daniel Gavelle and Carsten Bormann
who have provided useful discussion and input to the concepts in this who have provided useful discussion and input to the concepts in this
document. document.
8. Changelog 8. Changelog
Changes from -10 to 09: Changes from -10 to 11:
o Section 1: Amendments to remove discussing properties. o New Section 3.4 on Link Embedding
o o Removed disused "Service discovery" terminology
o Removed wording referring to discontinued function set concept
Changes from -09 to -10:
o Section 1: Amendments to remove discussing properties.
o New author and editor added. o New author and editor added.
Changes from -08 to 09: Changes from -08 to -09:
o Section 3.6: Modified to indicate that the entire collection o Section 3.6: Modified to indicate that the entire collection
resource is returned. resource is returned.
o General: Added editor's note with open issues. o General: Added editor's note with open issues.
Changes from -07 to 08: Changes from -07 to -08:
o Section 3.3: Modified Accepts to Accept header option. o Section 3.3: Modified Accepts to Accept header option.
o Addressed the editor's note in Section 4.1 to clarify the use of o Addressed the editor's note in Section 4.1 to clarify the use of
the Accept option. the Accept option.
Changes from -06 to 07: Changes from -06 to -07:
o Corrected Figure 1 sub-resource names e.g. tmp to temp and hum to o Corrected Figure 1 sub-resource names e.g. tmp to temp and hum to
humidity. humidity.
o Addressed the editor's note in Section 4.2. o Addressed the editor's note in Section 4.2.
o Removed section on function sets and profiles as agreed to at the o Removed section on function sets and profiles as agreed to at the
IETF#97. IETF#97.
Changes from -05 to -06: Changes from -05 to -06:
skipping to change at page 21, line 14 skipping to change at page 21, line 19
o Improved the WADL interface definition. o Improved the WADL interface definition.
o Added a simple profile example. o Added a simple profile example.
9. References 9. References
9.1. Normative References 9.1. Normative References
[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, DOI 10.17487/ Requirement Levels", BCP 14, RFC 2119,
RFC2119, March 1997, <https://www.rfc-editor.org/info/ DOI 10.17487/RFC2119, March 1997,
rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC5988] Nottingham, M., "Web Linking", RFC 5988, DOI 10.17487/
RFC5988, October 2010, <https://www.rfc-editor.org/info/
rfc5988>.
[RFC6690] Shelby, Z., "Constrained RESTful Environments (CoRE) Link [RFC6690] Shelby, Z., "Constrained RESTful Environments (CoRE) Link
Format", RFC 6690, DOI 10.17487/RFC6690, August 2012, Format", RFC 6690, DOI 10.17487/RFC6690, August 2012,
<https://www.rfc-editor.org/info/rfc6690>. <https://www.rfc-editor.org/info/rfc6690>.
[RFC8288] Nottingham, M., "Web Linking", RFC 8288,
DOI 10.17487/RFC8288, October 2017,
<https://www.rfc-editor.org/info/rfc8288>.
9.2. Informative References 9.2. Informative References
[I-D.ietf-core-dynlink] [I-D.ietf-core-dynlink]
Shelby, Z., Vial, M., Koster, M., and C. Groves, "Dynamic Shelby, Z., Koster, M., Groves, C., Zhu, J., and B.
Resource Linking for Constrained RESTful Environments", Silverajan, "Dynamic Resource Linking for Constrained
draft-ietf-core-dynlink-03 (work in progress), March 2017. RESTful Environments", draft-ietf-core-dynlink-04 (work in
progress), September 2017.
[I-D.ietf-core-resource-directory] [I-D.ietf-core-resource-directory]
Shelby, Z., Koster, M., Bormann, C., Stok, P., and C. Shelby, Z., Koster, M., Bormann, C., Stok, P., and C.
Amsuess, "CoRE Resource Directory", draft-ietf-core- Amsuess, "CoRE Resource Directory", draft-ietf-core-
resource-directory-11 (work in progress), July 2017. resource-directory-13 (work in progress), March 2018.
[I-D.ietf-core-senml] [I-D.ietf-core-senml]
Jennings, C., Shelby, Z., Arkko, J., Keranen, A., and C. Jennings, C., Shelby, Z., Arkko, J., Keranen, A., and C.
Bormann, "Media Types for Sensor Measurement Lists Bormann, "Media Types for Sensor Measurement Lists
(SenML)", draft-ietf-core-senml-10 (work in progress), (SenML)", draft-ietf-core-senml-13 (work in progress),
July 2017. March 2018.
[OIC-Core] [OIC-Core]
"OIC Resource Type Specification v1.1.0", 2016, "OIC Resource Type Specification v1.1.0", 2016,
<https://openconnectivity.org/resources/specifications>. <https://openconnectivity.org/resources/specifications>.
[OIC-SmartHome] [OIC-SmartHome]
"OIC Smart Home Device Specification v1.1.0", 2016, "OIC Smart Home Device Specification v1.1.0", 2016,
<https://openconnectivity.org/resources/specifications>. <https://openconnectivity.org/resources/specifications>.
[OMA-TS-LWM2M] [OMA-TS-LWM2M]
"Lightweight Machine to Machine Technical Specification", "Lightweight Machine to Machine Technical Specification",
2016, <http://technical.openmobilealliance.org/Technical/ 2016, <http://technical.openmobilealliance.org/Technical/
technical-information/release-program/current-releases/ technical-information/release-program/current-releases/
oma-lightweightm2m-v1-0>. oma-lightweightm2m-v1-0>.
[oneM2MTS0008]
"TS 0008 v1.3.2 CoAP Protocol Binding", 2016,
<http://www.onem2m.org/technical/published-documents>.
[oneM2MTS0023]
"TS 0023 v2.0.0 Home Appliances Information Model and
Mapping", 2016,
<http://www.onem2m.org/technical/published-documents>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66, RFC Resource Identifier (URI): Generic Syntax", STD 66,
3986, DOI 10.17487/RFC3986, January 2005, RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/info/rfc3986>. <https://www.rfc-editor.org/info/rfc3986>.
[RFC6573] Amundsen, M., "The Item and Collection Link Relations", [RFC6573] Amundsen, M., "The Item and Collection Link Relations",
RFC 6573, DOI 10.17487/RFC6573, April 2012, RFC 6573, DOI 10.17487/RFC6573, April 2012,
<https://www.rfc-editor.org/info/rfc6573>. <https://www.rfc-editor.org/info/rfc6573>.
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer [RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing", RFC Protocol (HTTP/1.1): Message Syntax and Routing",
7230, DOI 10.17487/RFC7230, June 2014, <https://www.rfc- RFC 7230, DOI 10.17487/RFC7230, June 2014,
editor.org/info/rfc7230>. <https://www.rfc-editor.org/info/rfc7230>.
[RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained [RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained
Application Protocol (CoAP)", RFC 7252, DOI 10.17487/ Application Protocol (CoAP)", RFC 7252,
RFC7252, June 2014, <https://www.rfc-editor.org/info/ DOI 10.17487/RFC7252, June 2014,
rfc7252>. <https://www.rfc-editor.org/info/rfc7252>.
[RFC7396] Hoffman, P. and J. Snell, "JSON Merge Patch", RFC 7396, [RFC7396] Hoffman, P. and J. Snell, "JSON Merge Patch", RFC 7396,
DOI 10.17487/RFC7396, October 2014, <https://www.rfc- DOI 10.17487/RFC7396, October 2014,
editor.org/info/rfc7396>. <https://www.rfc-editor.org/info/rfc7396>.
[oneM2MTS0008]
"TS 0008 v1.3.2 CoAP Protocol Binding", 2016,
<http://www.onem2m.org/technical/published-documents>.
[oneM2MTS0023]
"TS 0023 v2.0.0 Home Appliances Information Model and
Mapping", 2016,
<http://www.onem2m.org/technical/published-documents>.
Appendix A. Current Usage of Interfaces and Function Sets Appendix A. Current Usage of Interfaces and Function Sets
Editor's note: This appendix will be removed. It is only included Editor's note: This appendix will be removed. It is only included
for information. for information.
This appendix analyses the current landscape with regards the This appendix analyses the current landscape with regards the
definition and use of collections, interfaces and function sets/ definition and use of collections, interfaces and function sets/
profiles. This should be considered when considering the scope of profiles. This should be considered when considering the scope of
this document. this document.
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