Connectivity Framework Annex F: Assessment Template: MQTT
F. 6.5 Implementation Viewpoint F. 6.5.1 System Architecture Considerations
Peer-to-Peer vs. Broker:
( Section 4.2.1.1)
Data-Centric vs. Device / App-Centric:( Section 4.2.1.2)
Explicit vs. Implicit Governance:( Section 4.2.1.3)
F. 6.5.2 Data Considerations
Content-Based Selection( Section 4.2.2.1)
Time-Based Selection( Section 4.2.2.2)
Does the connectivity framework require running a special process or broker? Broker-based.
F. 6.5.3 Performance Considerations
Real-Time( Section 4.2.3.1)
Latency and Jitter vs. Throughput( Section 4.2.3.2)
It requires running MQTT-Server, a special broker process, for clients to communicate.
Does the application code( or business logic) have to be aware of the other endpoints in order to participate in information exchange?
The application code( or business logic) does not have to be aware of the other endpoints to participate in data exchange. MQTT is only a connectivity transport. Data-centric or device-centric connectivity frameworks can be built with application-specific code. Is the governance explicit and shareable?
No, the governance is not explicit and shareable. Governance is enforced by the server implementation. The means for this are not standardized.
Can a content-filter specify the data subset of interest?
No, the data subset of interest cannot be specified by content. The content is opaque to MQTT. Can sub-sampling specify the data subset of interest?
No, one cannot subscribe to a sub-sampled data subset of interest. MQTT attempts to deliver the published messages to all the subscribers on a topic.
Does the connectivity technology support real-time data distribution? Is the latency deterministic( smaller jitter is better)?
No, MQTT is a TCP and broker-based protocol, and is not intended for real-time.
Binary protocol offers low overhead, but the use of TCP and relay via a broker provides non-deterministic latency. How does the latency and jitter change with throughput? What limits the throughput?
Implementation dependent, but use of a broker is likely to make latency highly dependent on throughput.
Small protocol overhead benefits throughput, but the use of broker limits this to what a single broker can relay.
IIC: PUB: G5: V1.0: PB: 20170228- 117-