message communication protocols in IoT

Design Principles for the Web Connectivity
Web Communication
protocols
Introduction for web
Connectivity
Web Connectivity
Message
Communication
protocols

Message Communication protocols
Terminology:
Request/Response
(Client/Server)
Publish/Subscribe (pubsub)
Resource Directory
Resource Discovery
Pull (Subscribe/Notify) Data
Polling or Observing
Push (Publish/Subscribe) Data
Message Cache
Message Queue
Information/Query
Communication Protocols:
• CoAP-SMS
• CoAP-MQ
• MQTT Protocol
XMPP (Extensible Messaging and Presence
Protocol)
• XML
• XMPP

Request/Response
(Client/Server)
Resource Directory
Resource Discovery
Message Cache
Message Queue
Information/Query
A request/response message exchange refers
to an object (client) requesting for resource(s)
and an object (server) sending the
response(s).

Request/Response
(Client/Server)
Resource Directory
Resource Discovery
Message Cache
Message Queue
Information/Query
• A service publishes the messages; for
example, a weather information service
publishes the messages of weather reports
for the potential receivers.
• A service can be availed by one or more
clients or brokers. When a client subscribes
to the service, it receives messages from
that service.

Request/Response
(Client/Server)
Resource Directory
Resource Discovery
Message Cache
Message Queue
Information/Query
Resource directory (RD)5 maintains
information and values for each resource
type. A resource of a resource type accesses
from the RD using URI for the resource.

Request/Response
(Client/Server)
Resource Directory
Resource Discovery
Message Cache
Message Queue
Information/Query
Resource discovery service may advertise
(publish) at regular intervals, the availability
of the resources or types of the resources
available and their states. A client discovers
the resource type and registers for the RD
service.

Request/Response
(Client/Server)
Resource Directory
Resource Discovery
Message Cache
Message Queue
Information/Query
Pull means pulling a resource, value, message or data
of a resource-type by registering and subscribing. Pull
may be using GET or on initiating OBSERVE. The
server maintains state information for a resource and
notifies on change of state. Client pulls again the
resource on the change.

Request/Response
(Client/Server)
Resource Directory
Resource Discovery
Message Cache
Message Queue
Information/Query
Polling means finding from where new
messages would be available or whether new
messages are available, or updates are
available or whether the information needs to
be refreshed or finding the status if the state

Request/Response
(Client/Server)
Resource Directory
Resource Discovery
Message Cache
Message Queue
Information/Query
Push means a service that pushes the
messages or information regularly. Interested
device or endpoint or potential receiver
receives these pushes. For example, a mobile
service provider pushes the temperature and
location information regularly for the

Request/Response
(Client/Server)
Resource Directory
Resource Discovery
Message Cache
Message Queue
Information/Query
Cache means storing when available and can
be used later when required. Message's cache
is useful in an environment of short or
prolonged disconnections of a service. A
message can be accessed once or more times

Request/Response
(Client/Server)
Resource Directory
Resource Discovery
Message Cache
Message Queue
Information/Query
Message queuing means storing the messages
(data) in sequence from devices or endpoints
so that when connection state changes then
messages can be forwarded. Forwarding is
done using the first-in first-out method for a
resource type.

Request/Response
(Client/Server)
Resource Directory
Resource Discovery
Message Cache
Message Queue
Information/Query
The method is that an object (client) requests
information using a query while another end-
object (server) responds by replying to the
query. The responding application processes
the query using the query optimizer and
retrieval plan.

Terminology:
Request/Response (Client/Server)
Resource Directory
Resource Discovery
Message Cache
Message Queue
Information/Query
Communication Protocols:
• CoAP-SMS
• CoAP-MQ
• MQTT Protocol
XMPP (Extensible Messaging and Presence
Protocol)
• XML
• XMPP

• CoAP-SMS is a protocol when
CoAP object uses IP as well as
cellular networks and uses SMS.
• It is an alternative to UDP-DTLS
over ROLL for CoAP object
messages and when using cellular
communication.
• SMS is used instead of UDP +
DTLS by a CoAP client or server.
• A CoAP client communicates to a
mobile terminal (MT) endpoint
over the General Packet Radio
Service (GPRS), High Speed Packet
Access (HSPA) or Long-Term
Evolution (LTE) networks using
CoAP-SMS protocol.

Following is the IETF recommended
terminology for use:
• SMS-C: SMS service Centre
• SMS-SP SMS service provider
• CIMD: Computer interface to message
distribution
• MS: Mobile station at a cellular network
functioning as CoAP client or CoAP
sever
• MO: Machine or IoT device or mobile
origin functioning as CoAP client
• MT: Machine or IoT device or mobile
terminal functioning as CoAP sever
• SMPP: Short message peer-to peer
for CoAP-Data. Peer-to-peer means
sending requests as well as receiving
requests
• SS7: Signaling Service Protocol
• UCP/UMI: Universal computer
interface protocol/machine interface
for short message delivery contained
in a CoAP request or CoAP response

• A CoAP message encodes with
alphabets for SMS communication.
An SMS message consists of 160
characters in 7-bit encoding of a
character.
• Maximum length for a CoAP message is
thus 140 B.
• CoAP endpoints have to work with a
Subscriber Identity Module (SIM) card
for SMS in cellular networks. The points
are addressed by using Mobile Station
ISDN (MSISDN) number.
• Does not support multi-casting
• Two additional options are Response-to-
URI-Host (RUH) and Response-to-URI-Port
(RUP)
• An MS/CoAP client sends a SMS request
(SMS-SUBMIT) to SMS-C;
• SMS-C reports using SMS-SUBMIT-REPORT;
• SMS-C sends SMS (SMS-DELIVER) to
MS/CoAP server;
• The server reports using SMS-
DELIVERREPORT; and SMS-C sends SMS-
STATUS-REPORT to the client.

• CoAP-MQ is a message queue
protocol using a broker and RD.
• Roles of CoAP endpoints have
roles as a client and server.

Message Queuing Telemetry
Transport (MQTT) is an open-
source protocol for machine-to
machine (M2M)/IoT connectivity.

MQTT Broker does the following:
• Functions as a server node capable of storing messages from publishers and forwarding
them to the subscribing clients.
• Receives topics from the publishers. Examples of topics are measured information of
ambient light conditions, traffic density, nearby parking space availability and waste
container status.
• Performs a store-and-forward function.
• Receives subscriptions from clients.
• Recovers subscriptions on reconnect after a disconnection.
• Acts as a broker between the publisher and subscribers.
• Authentication by Username/Password in connect message and client security is through

Web Communication
protocols
Introduction for web
Connectivity
Web Connectivity
Message
Communication
protocols

message communication protocols in IoT

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message communication protocols in IoT