Connectivity Framework Annex F : Assessment Template : MQTT
F . 6.5 Implementation Viewpoint F . 6.5.4 Scalability Considerations
Data Objects ( Section 4.2.4.1 )
Apps ( Section 4.2.4.2 )
F . 6.5.5 Availability Considerations
Redundancy ( Section 4.2.5.1 )
Recovery ( Section 4.2.5.2 )
F . 6.5.6 Deployment Considerations
Platforms Constraints ( Section 4.2.6.1 )
Incremental Upgrades ( Section 4.2.6.2 )
Can the connectivity framework effectively handle an increasing number of data objects ? What limits data object size ?
MQTT does not provide a notion of data objects or data object caching ; just the notion of a Topic . The number of topics supported by a MQTT-Server will depend on the server memory and the number of clients . The number of clients will be limited by the capabilities of the MQTT broker and the number of connections it can sustain .
There are no explicit message-size limits in MQTT , since it runs over TCP . MQTT-SN messages are over UDP will limit message size to what it can fit in a network datagram ( 64KB ).
Can the connectivity framework effectively support interface evolution for an increasing number of distributed application components ?
Yes , MQTT can effectively support interface evolution for an increasing number of distributed application components , since the message are opaque . However , the applications will need to manage the message versioning and evolution .
Can the connectivity framework support continuous availability over a defined systemrelevant time period ?
No , MQTT-Server does not support continuous availability over a defined system-relevant time period . The single point of failure introduced by the MQTT-Server will impact availability . Can the connectivity framework support recovery when fault conditions occur ? No , MQTT does not support recovery when fault conditions occur .
Broker health should be monitored to ensure system availability . There should be mechanisms in place to re-start the broker in case of malfunction or failure .
Does the connectivity framework support the operating system ( OS ), the CPU and the resource constraints on the platform ( s ) being used ?
MQTT is available for a number of platforms . Open-source implementations are available and could be built for target platforms . Does the connectivity framework facilitate incremental upgrades ?
Yes , MQTT can facilitate incremental upgrades , since it is built on the publish-subscribe data exchange pattern .
During deployment , the main requirement is to configure all clients to connect to the same broker .
The centralization of the configuration on the broker simplifies deployment but it requires provisioning and maintenance of a service that is separate from all client applications that is common to all .
Integrating separate applications developed using different brokers requires consolidation of the brokers .
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