CoRE A. Bhattacharyya
Internet Draft S. Bandyopadhyay
Intended status: Standards track A. Pal
Expires: July 2014 Tata Consultancy Services Ltd.
January 29, 2014
CoAP option for no server-response
draft-tcs-coap-no-response-option-05
Abstract
There can be typical M2M scenarios where responses from the data
sink to the data source against request/ notification from the
source might be considered redundant. This kind of open-loop
exchange (with no reverse path from the sink to the source) may be
desired while updating resources in constrained systems looking for
maximized throughput with minimized resource consumption. CoAP
already provides a non-confirmable (NON) mode of exchange where The
receiving end-point does not respond with ACK. However, the
receiving end-point responds the sender with a status code
indicating "the result of the attempt to understand and satisfy the
request".
This draft introduces a header option: 'No-Response' to suppress
responses from the receiver and discusses exemplary use cases which
motivated this proposition based on real experience. This option
also provides granularity by allowing suppression of a typical class
or a combination of classes of responses. This option may be
effective for both unicast and multicast scenarios.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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Task Force (IETF), its areas, and its working groups. Note that
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at any time. It is inappropriate to use Internet-Drafts as
reference material or to cite them other than as "work in progress."
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Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
Internet-Drafts are draft documents valid for a maximum of six
months and may be updated, replaced, or obsoleted by other documents
at any time. It is inappropriate to use Internet-Drafts as
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This Internet-Draft will expire on July 29, 2014.
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Table of Contents
1. Introduction ................................................ 3
1.1. Granular suppression of responses ....................... 3
1.2. Terminology ............................................ 4
2. Potential benefits .......................................... 4
3. Exemplary application scenarios .............................. 4
3.1. Frequent update of geo-location from vehicles to backend
(Category 1) ................................................ 5
3.1.1. Benefits using No-Response ......................... 5
3.2. Multicasting traffic congestion information to PDAs/ smart-
phones (Category 2) ......................................... 6
3.2.1. Using granular response suppression ................ 6
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3.2.2. Benefits using No-Response ......................... 6
4. Option Definition ........................................... 6
4.1. Achieving granular suppression .......................... 8
5. Miscellaneous aspects ........................................ 9
5.1. Re-use interval for message IDs ........................ 10
5.2. Taking care of congestion .............................. 10
5.3. Duality with the 'Observe' option ...................... 10
6. Example .................................................... 11
6.1. Request/response Scenario .............................. 11
6.1.1. Using No-Response with PUT ........................ 11
6.1.2. Using No-Response with POST ....................... 12
6.1.2.1. POST updating a target resource .............. 12
6.1.2.2. POST performing updates through resource creation
..................................................... 12
6.2. Resource-observe Scenario .............................. 13
6.3. An end-to-end system combining No-response and Observe . 15
7. IANA Considerations ........................................ 17
8. Security Considerations .................................... 17
9. Acknowledgments ............................................ 17
10. References ................................................ 17
10.1. Normative References .................................. 17
10.2. Informative References ................................ 18
1. Introduction
This draft proposes a new header option 'No-Response' for
Constrained Application Protocol (CoAP). This option enables the
sender end-point to explicitly express its disinterest in getting
responses back from the receiving end-point. By default this option
expresses disinterest in any kind of response. This option should be
applicable along with non-confirmable (NON) updates. At present this
option will have no effect if used with confirmable (CON) mode.
Along with the technical details this draft presents some practical
application scenarios which should bring out the utility of this
option.
1.1. Granular suppression of responses
This option enables granularity by allowing the sender to choose the
typical class or combination of classes of responses which it is
disinterested in. For example, a sender may explicitly tell the
receiver that no response is required unless something 'bad' happens
and a response of class 4.xx or 5.xx is to be fed back to the
sender. No response is required in case of 2.xx classes. A similar
scheme is described in Section 3.7 of [I-D.ietf-core-groupcomm] on
the server side. Here the server may perform granular suppression
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for group communication. But in this case the server itself decides
whether to suppress responses or not. This option enables the
clients to explicitly inform the server about the disinterest in
responses.
1.2. Terminology
The terms used in this draft are in conformance with those defined
in [I-D.ietf-core-coap].
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC-2119.
2. Potential benefits
If this option is opportunistically used with fitting M2M
applications then the concerned systems may benefit in the following
aspects:
* Reduction in network clogging
* Reduction in server-side loading
* Reduction in battery consumption at the constrained end-point
* Reduction in communication cost at the constrained end-point
* May help to satisfy hard real-time requirements (since,
waiting due to closed loop latency is completely avoided)
3. Exemplary application scenarios
The described scenarios are confined within a communication pattern
where there is a direct communication channel between a constrained
device (the device may well be a constrained gateway) and an
unconstrained backend. Also, we consider only the scenario of data
updates which happen through a push to the server by the client
using PUT or POST.
The application scenarios are classified into 2 categories as below:
Category 1) Data-source=constrained device; Data-sink=backend.
Category 2) Data-source=backend; Data-sink=constrained device.
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Next sub-section describes the user stories and the potential
benefits in each of the cases through the use of No-Response option.
An Intelligent Traffic System (ITS) is considered as the base
application. The application scenarios are formed out of the
different aspects of ITS.
3.1. Frequent update of geo-location from vehicles to backend (Category
1)
Each vehicle in ITS is equipped with a sensor-gateway comprising
sensors like GPS and Accelerometer. The sensor-gateway connects to
the Internet using a low-bandwidth cellular (e.g. GPRS) connection.
The GPS co-ordinates are periodically updated to the backend server
by the gateway. In case of ITS the update rate is adaptive to the
motional-state of the vehicle. If the vehicle moves fast the update
rate is high as the position of the vehicle changes rapidly. If the
vehicle is static or moves slowly then the update rate is low. This
ensures that bandwidth and energy is not consumed unnecessarily. The
motional-state of the vehicle is inferred by a local analytics
running on the sensor-gateway which uses the accelerometer data and
the rate of change in GPS co-ordinates. The back-end server hosts
applications which use the updates for each vehicle and produce
necessary information for remote users.
Retransmitting a location co-ordinate which is already passed by a
vehicle is not efficient as it adds redundant traffic to the
network. So, the updates are done in NON mode. However, given the
thousands of vehicles updating frequently, the NON exchange will
also trigger huge number of status responses from the backend. Each
response in the air is of 4 bytes of application layer plus several
bytes originating from the lower layers. Thus the cumulative load on
the network will be quite significant.
On the contrary, if the edge devices explicitly declare that they do
not need any status response then significant load will be reduced
from the network and the server as well. The assumption is that
since the update rate is high stray losses in geo-locations will be
compensated with the large update rate and thereby not affecting the
end applications.
3.1.1. Benefits using No-Response
Thus mapping the above scenario to the benefits mentioned in section
2 reveals that use of 'No-Response' will help in:
* Reduction in network clogging
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* Reduction in server-side loading
* Help in achieving real-time requirements as the application is
not bound by any delay due to closed loop latency
3.2. Multicasting traffic congestion information to PDAs/ smart-phones
(Category 2)
The ITS might have an application which runs some analytics at the
backend and determines the instantaneous traffic congestion spots in
a city. The analytics is done based on the real-time geo-location
updates received from the vehicles registered in the system. The
backend application multicasts the instantaneous results of the
analytics to the constrained handheld devices which registered to
the city authority for real-time updates on congestion points. The
backend is not really interested in the delivery status of these
updates. In this case the backend uses No-Response option along with
NON updates to reduce the traffic generated due to simultaneous
status responses from hundreds of subscribed handheld devices.
3.2.1. Using granular response suppression
However, an intelligent application may use the granularity feature
of this option such that the responses are fed-back to the backend
when updates to particular devices cause errors. So the updates may
contain 'No-Response' option indicating that a response is to be
suppressed only in success conditions and all responses in case of
errors should be fed back. The server might eventually stop sending
updates to the devices which responded with consecutive 'bad'
responses. This will indirectly help saving network bandwidth.
3.2.2. Benefits using No-Response
Thus mapping the above scenario to the benefits mentioned in section
2 reveals that use of 'No-Response' will help in:
* Reduction in network clogging
* Reduction in battery consumption at the constrained end-point
* Reduction in communication cost at the constrained end-point
4. Option Definition
The properties of this option are as in Table 1.
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+--------+---+---+---+---+-------------+--------+--------+---------+
| Number | C | U | N | R | Name | Format | Length | Default |
+--------+---+---+---+---+-------------+--------+--------+---------+
| TBD | | X | - | | No-Response | uint | 1 | 0 |
+--------+---+---+---+---+-------------+--------+--------+---------+
Table 1: Option Properties
This option is Elective and Non-Repeatable. If a proxy happens to
encounter this option it should not forward. Hence caching is not
applicable. The assumption here is that if an application needs a
proxy in between an unconstrained backend and a constrained node
then in most cases the leg between the constrained node and the
proxy will be constrained in nature. So by restricting this option
up to the proxy we can reap the benefits of this option in
constrained environment without increasing overall complexity.
This option is presently intended for update requests (e.g., PUT) in
NON mode and should have no effect if used with a CON request. This
option contains values to indicate interest/ disinterest in all or a
particular class or combination of classes of responses as described
in the next sub-section.
The following table provides a 'ready-reckoner' on possible
applicability of this option for all the four REST methods. This
table is prepared in view of the type of application scenarios
foreseen so far.
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+-------------+----------------------------------------------------+
| Method Name | Remarks on applicability |
+-------------+----------------------------------------------------+
| GET | Not applicable. |
+-------------+----------------------------------------------------+
| | Applicable for frequent updates in NON mode on |
| PUT | existing fixed resources. Might not be useful when |
| | PUT 'creates' a new resource. |
+-------------+----------------------------------------------------+
| | If POST is used just to update a target resource |
| | then No-Response can be used in the same manner as |
| | in NON-PUT. May also be applicable when POST |
| | performs resource creation and the client does not |
| | refer to the resource in future. For example, than |
| | updating a fixed resource, POST API may rather |
| POST | contain a query-string with name/value pairs for a |
| | defined action (ex. insertion into a database as |
| | part of frequent updates). The resources created |
| | this way may be 'short-lived' resources which the |
| | client will not refer to in future (see section |
| | 5.1.2.2). |
+-------------+----------------------------------------------------+
| | Not applicable. Deletion is usually a permanent |
| DELETE | action and the client should make sure that the |
| | deletion actually happened. |
+-------------+----------------------------------------------------+
Table 2: Applicability of No-Response for different methods
4.1. Achieving granular suppression
This option is defined as a bit-map (Table 3) to achieve granular
suppression.
+-------+-----------------------+---------------------------------+
| Value | Binary Representation | Description |
+-------+-----------------------+---------------------------------+
| 0 | 00000000 | Suppress all responses (same as |
| | | empty value). |
+-------+-----------------------+---------------------------------+
| 2 | 00000010 | Allow 2.xx success responses. |
+-------+-----------------------+---------------------------------+
| 8 | 00001000 | Allow 4.xx client errors. |
+-------+-----------------------+---------------------------------+
| 16 | 00010000 | Allow 5.xx server errors. |
+-------+-----------------------+---------------------------------+
Table 3: Option values
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XOR of the values defined for allowing particular classes will
result in allowing a combination of classes of responses. So, a
value of 18 (binary: 00010010) will result in allowing all 2.xx and
5.xx classes of responses. It is to be noted that a value of 26 will
indicate that all types of responses are to be allowed (which is as
good as not using No-Response at all).
Implementation Note: The use of No-Response option is very much
driven by the application scenario and the characteristics of the
information to be updated. Judicious use of this option benefits
the overall system as explained in sections 2 and 3.
When No-Response is used with empty or 0 value, the updating
end-point should cease the listening activity for response
against the particular request. On the contrary, opening up at
least one class of responses means that the updating end-point
can no longer stop listening and must be configured to listen up
to some application specific time-out period for the particular
request. The updating end-point never knows whether the present
update will be a success or a failure. Thus, if the client
decides to open up the responses for errors (4.xx & 5.xx) then it
has to wait for the entire time-out period even for the instances
where the request is successful (and the server is not supposed
to send back a response). This kind of situation may arise for
the scenario in section 3.2.1. Under such circumstances the use
of No-Response may not help improving the performance in terms of
overall latency. However, the advantages in terms of saving
network and energy resources will still hold.
A point to be noted in view of the above example is that there
may be situations when the response on errors might get lost. In
such a situation the sender would wait up to the time-out period
but will not receive any response. But this should not lead to
the impression to the sender that the request was successful. The
situation will worsen if the receiver is no longer active. The
application designer needs to tackle such situation. Since this
option is conceived for frequent updates, the sender may
strategically insert requests without No-Response after N numbers
of requests with No-Response 'weaves' CON notifications within
series of NON notifications to check if the observer is alive).
5. Miscellaneous aspects
This section further describes few important implementation aspects
worth considering while using No-Response. As mentioned in the
previous section, judicious use of this option enables the
application developer to enhance the overall system throughput. To
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keep the flexibility on the application developer part, the
following discussion does not mandate anything, rather provides
suggestive guidelines.
Another point is: although this option is primarily conceived
following the scenario of frequent updates on a particular resource
by a particular client but that may not be the case always. These
updates may not necessarily correspond to change of state of any
particular resource. There may be scenarios where a constrained
sensor gateway gets random updates from different sensors whose
resources are hosted in the gateway.
5.1. Re-use interval for message IDs
Since No-Response is primarily based on CoAP-NON, 'NON-LIFETIME' (as
defined in section 4.8.2 of [I-D.ietf-core-coap]) is suggested as the
time interval over which a message ID can be safely re-used.
5.2. Taking care of congestion
The possible communication scenarios taking advantage of 'No-
Response' should primarily fall into the class of low-data volume
applications as described in section 3.1.2 of [RFC 5405]. Precisely,
this should map to the scenario where the application cannot
maintain an RTT estimate. Hence, following [RFC 5405] , a 3s interval is
suggested as the minimum interval between successive updates.
However, an application developer MAY interweave occasional closed-
loop exchanges (e.g. CoAP-NON without No-Response or CoAP-CON) to
get an RTT estimate between the end-points and adjust time-to-time
the interval between updates.
5.3. Duality with the 'Observe' option
Scenarios like frequent update of a given resource at server by a
client using No-Response leads to an interesting observation. The
'No-Response' option actually complements the 'Observe' option with
NON-notifications ([I-D.ietf-core-observe]). In case of the later the
update notifications from the server reach the observer client
without triggering any response from the observer. However, there is
a difference in the point of interest. In the 'Observe' scenario the
interest is expressed by the 'consumer' to get the data. On the
contrary, the updates using 'No-Response' applies to the scenario
when it is the interest of the 'producer' to update the data. Thus
'No-Response' and 'Observe' using NON-notification may be combined
together, under permitting condition, to achieve high performance
gain in an end-to-end producer-consumer application. A typical
example is illustrated in section 6.
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6. Example
This section illustrates few examples of exchanges based on the
scenario narrated in section 3.1. Examples for other scenarios can
be easily conceived based on these illustrations.
6.1. Request/response Scenario
6.1.1. Using No-Response with PUT
Figure 1 shows a typical request with this option. The depicted
scenario occurs when the vehicle#n moves very fast and update rate
is high. The vehicle is assigned a dedicated resource: vehicle-stat-
<n>, where <n> can be any string uniquely identifying the vehicle.
The update requests are in NON mode. The No-Response option causes
the server not to reply with any status code.
Client Server
| |
| |
+----->| Header: PUT (T=NON, Code=0.03, MID=0x7d38)
| PUT | Token: 0x53
| | Uri-Path: "vehicle-stat-00"
| | Content Type: text/plain
| | No-Response: 0
| | Payload:
| | "VehID=00&RouteID=DN47&Lat=22.5658745&Long=88.4107966667&
| | Time=2013-01-13T11:24:31"
| |
[No response from the server. Next update in 20 secs.]
| |
+----->| Header: PUT (T=NON, Code=0.03, MID=0x7d39)
| PUT | Token: 0x54
| | Uri-Path: "vehicle-stat-00"
| | Content Type: text/plain
| | No-Response: 0
| | Payload:
| | "VehID=00&RouteID=DN47&Lat=22.5649015&Long=88.4103511667&
| | Time=2013-01-13T11:24:51"
Figure 1: Exemplary unreliable update with No-Response option using
PUT.
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6.1.2. Using No-Response with POST
POST "usually results in a new resource being created or the target
resource being updated". Exemplary uses of 'No-Response' for both
these 'usual' actions of POST are given below.
6.1.2.1. POST updating a target resource
In this case POST acts the same way as PUT. The exchanges are same
as above. The updated values are carried as payload of POST as shown
in Figure 2.
Client Server
| |
| |
+----->| Header: POST (T=NON, Code=0.02, MID=0x7d38)
| POST | Token: 0x53
| | Uri-Path: "vehicle-stat-00"
| | Content Type: text/plain
| | No-Response: 0
| | Payload:
| | "VehID=00&RouteID=DN47&Lat=22.5658745&Long=88.4107966667&
| | Time=2013-01-13T11:24:31"
| |
[No response from the server. Next update in 20 secs.]
| |
+----->| Header: PUT (T=NON, Code=0.02, MID=0x7d39)
| POST | Token: 0x54
| | Uri-Path: "vehicle-stat-00"
| | Content Type: text/plain
| | No-Response: 0
| | Payload:
| | "VehID=00&RouteID=DN47&Lat=22.5649015&Long=88.4103511667&
| | Time=2013-01-13T11:24:51"
Figure 2: Exemplary unreliable update with No-Response option using
POST as the update-method.
6.1.2.2. POST performing updates through resource creation
In most practical implementations the backend of section 3.1 will
have a dedicated database to store the location updates. In such a
case the client would send an update string as the POST URI which
contains the name/value pairs for each update. Thus frequent updates
may be performed through POST by creating such 'short-lived'
resources which the client would not refer to in future. Hence 'No-
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Response' can be used in same manner as for updating fixed
resources. The scenario is depicted in Figure 3.
Client Server
| |
| |
+----->| Header: POST (T=NON, Code=0.02, MID=0x7d38)
| POST | Token: 0x53
| | Uri-Path: "insertInfo"
| | Uri-Query: "VehID=00"
| | Uri-Query: "RouteID=DN47"
| | Uri-Query: "Lat=22.5658745"
| | Uri-Query: "Long=88.4107966667"
| | Uri-Query: "Time=2013-01-13T11:24:31"
| | No-Response: 0
| |
[No response from the server. Next update in 20 secs.]
| |
+----->| Header: POST (T=NON, Code=0.02, MID=0x7d39)
| POST | Token: 0x54
| | Uri-Path: "insertInfo"
| | Uri-Query: "VehID=00"
| | Uri-Query: "RouteID=DN47"
| | Uri-Query: "Lat=22.5649015"
| | Uri-Query: "Long=88.4103511667"
| | Uri-Query: "Time=2013-01-13T11:24:51"
| | No-Response: 0
| |
Figure 3: Exemplary unreliable update with No-Response option using
POST with a query-string to insert update information to backend
database.
6.2. Resource-observe Scenario
This option should be treated transparently if used with NON
notifications. In other words, just like GET and DELETE, this option
will have no effect for observe notifications. The following example
demonstrates how optimizations achieved using No-Response may also
be achieved using resource-observe mode in certain situations at
least in theory.
For example, the scenario of section 3.1 may also be achieved using
resource-observe. In that case the backend will have to subscribe to
each of the in-vehicle sensor gateway. The gateways will notify the
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backend with updated geo-locations. However, considering the huge
number of vehicles moving around and several being added to the
system quite often, this kind of arrangement may not be as
practicable and efficient solution as illustrated in the previous
examples.
Figure 4 shows the resource observe variant. The No-Response option
has been used intentionally both with GET and the notifications to
illustrate the non-applicability of this option in this situation.
Server Client
| |
|<-----+ Header : GET (MID=0x5d28)
| GET | Token : 0x53
| | No-Response: 0
| | Uri-Path: vehicle-stat
| | Observe : (empty)
| |
| |
+----->| Header: 2.05 (T=NON, MID=0x7d38)
| 2.05 | Token: 0x53
| | Content Type: text/plain
| | No-Response: 0
| | Payload:
| | "VehID=00&RouteID=DN47&Lat=22.5658745&Long=88.4107966667&
| | Time=2013-01-13T11:24:31"
| |
[Next update in 20 secs.]
| |
+----->| Header: 2.05 (T=NON, MID=0x7d39)
| 2.05 | Token: 0x53
| | Content Type: text/plain
| | No-Response: 0
| | Payload:
| | "VehID=00&&RouteID=DN47&Lat=22.5649015&Long=88.4103511667&
| | Time=2013-01-13T11:24:51"
Figure 4: Exemplary unreliable update in resource-observe mode with
No-Response option where practically No-Response has no effect.
Note: The reason for keeping this example is to open up the choice
to the user when there is a possibility of choosing between
resource-observe with NON and updates with No-Response and to
show a possible case where the latter option may sound more
useful.
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6.3. An end-to-end system combining No-response and Observe
This example illustrates the scenario pointed out in section 5.3
above. The 'No-Response' option can be combined with the 'Observe'
option with NON-notifications to create a lightweight end-to-end
producer-consumer system. For example, the vehicular updates from a
remote vehicle may be observed by a remote observer in a PDA as
shown in figure 5.
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Producer Server Consumer
(Client) (Client)
| | |
| | <-----+
| | GET |
+-----> | (Observe: empty, Token: 30)|
| POST | |
| | Header: POST (T=NON, Code=0.02, MID=0x7d38) |
| | Token: 0x53 |
| | Uri-Path: "insertInfo" |
| | Uri-Query: "VehID=00" |
| | Uri-Query: "RouteID=DN47" |
| | Uri-Query: "Lat=22.5658745" |
| | Uri-Query: "Long=88.4107966667" |
| | Uri-Query: "Time=2013-01-13T11:24:31" |
| | No-Response: 0 |
| | |
| +-----> |
| | 2.05 (T=NON, MID=0x5d40, Token: 30) |
| | Payload: |
| | "VehID=00&RouteID=DN47&Lat=22.5658745& |
| | Long=88.4107966667& Time=2013-01-13T11:24:31"|
| | |
[No response |
from the server. |
Next update in 20 secs.] |
| | |
+-----> | Header: POST (T=NON, Code=0.02, MID=0x7d39) |
| POST | Token: 0x54 |
| | Uri-Path: "insertInfo" |
| | Uri-Query: "VehID=00" |
| | Uri-Query: "RouteID=DN47" |
| | Uri-Query: "Lat=22.5649015" |
| | Uri-Query: "Long=88.4103511667" |
| | Uri-Query: "Time=2013-01-13T11:24:51" |
| | No-Response: 0 |
| | |
| +-----> |
| | 2.05 (T=NON, MID=0x5d41, Token: 30) |
| | Payload: |
| | "VehID=00&RouteID=DN47&Lat=22.5649015& |
| | Long=88.4103511667& Time=2013-01-13T11:24:51"|
| | |
Figure 5: Exemplary end-to-end update and observe scenario using
'No-Response' for NON-updates from 'producer' and observe with NON-
notifications by the 'consumer'.
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7. IANA Considerations
The IANA is requested to add the following option number entries:
+--------+--------------+----------------------------+
| Number | Name | Reference |
+--------+--------------+----------------------------+
| TBD | No-Response | Section 4 of this document |
+--------+--------------+----------------------------+
8. Security Considerations
The No-Response option defined in this document presents no security
considerations beyond those in Section 11 of the base CoAP
specification [I-D.ietf-core-coap].
9. Acknowledgments
Thanks to Carsten Bormann, Esko Dijk, Bert Greevenbosch, Akbar
Rahman and Claus Hartke for their valuable inputs.
10. References
10.1. Normative References
[I-D.ietf-core-coap]
Shelby, Z., Hartke, K. and Bormann, C.,"Constrained Application
Protocol (CoAP)", draft-ietf-core-coap-18, June 28, 2013
[I-D.ietf-core-observe]
Hartke, K.,"Observing Resources in CoAP", draft-ietf-core-observe-
09, July 15, 2013
[I-D.ietf-core-groupcomm]
Rahman, A. and Dijk, E.,"Group Communication for CoAP", draft-ietf
core-groupcomm-12, July 30, 2013
[RFC 5405]
Eggert, L. and Fairhurst, G.," Unicast UDP Usage Guidelines for
Application Designers"
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10.2. Informative References
[MOBIQUITOUS 2013]
Bhattacharyya, A., Bandyopadhyay, S. and Pal, A., "ITS-light:
Adaptive lightweight scheme to resource optimize intelligent
transportation tracking system (ITS)-Customizing CoAP for
opportunistic optimization", 10th International Conference on Mobile
and Ubiquitous Systems: Computing, Networking and Services
(Mobiquitous 2013), December, 2013.
[Sensys 2013]
Bandyopadhyay, S., Bhattacharyya, A. and Pal, A., "Adapting protocol
characteristics of CoAP using sensed indication for vehicular
analytics", 11th ACM Conference on Embedded Networked Sensor Systems
(Sensys 2013), November, 2013.
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Authors' Addresses
Abhijan Bhattacharyya
Tata Consultancy Services Ltd.
Kolkata, India
Email: abhijan.bhattacharyya@tcs.com
Soma Bandyopadhyay
Tata Consultancy Services Ltd.
Kolkata, India
Email: soma.bandyopadhyay@tcs.com
Arpan Pal
Tata Consultancy Services Ltd.
Kolkata, India
Email: arpan.pal@tcs.com
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