*Interaction Protocols for Multi-Robot Systems in Industry 4.0 DOI: http://dx.doi.org/10.5772/intechopen.97481*

**Figure 10.**

Accountability (Authentication, Authorization and Accountability). In the confi-

The IoT supports some communication standards that can be defined as:

• In the Telemetry standard, information is sent from devices to the cloud,

• In the query pattern, devices send requests to the cloud to collect information;

• In the Commands pattern, Systems send commands to devices so that they can

• In the Notification standard, Systems send information to devices in order to

As can be seen in **Figure 8**, the pattern Telemetry becomes suitable for the MQTT protocol, because it has a public/subscribed model, which is equivalent to the telemetry standard. CoAP is not suitable for the Telemetry standard because the connection needs from the system (client) to the server, which faces addressing problems such as mobile roaming or NAT [9]. The CoAP protocol has a better performance for the query communication pattern in relation to the MQTT protocol, since it is based on the request/response model (**Figure 9**). The MQTT has a

dentiality field, the encryptions used by the protocol are described.

inform possible changes in the state of the physical world;

*Telemetry communication pattern example for (a) MQTT, (b) CoAP.*

*Example of communication pattern notification for (a) MQTT, (b) CoAP.*

**4.4 Communication standards**

*Robotics Software Design and Engineering*

perform specific activities;

**Figure 8.**

**Figure 9.**

**164**

informing possible changes in states;

*Communication pattern example query for (a) MQTT, (b) CoAP.*

**Figure 11.** *Communication pattern example command for (a) MQTT, (b) CoAP.*

certain difficulty of implementation in the *Consultation* pattern because it has the need to define a response topic for the communication since there is no way for it to be readily constructed (**Figure 10**).

For the *Command* pattern, both protocols face difficulties. CoAP faces the same addressing problems detailed in textit Telemetry and MQTT does not support native result paths, thus requiring a results topic (**Figure 11**).

Finally, in the *Notification* pattern, the CoAP addressing problems, also listed in the Command and Telemetry patterns, are present. On the other hand, the model MQTT publishes/subscribes to the notification architecture, presenting problems only if better flow control is needed for a large amount of data at high rates [4].
