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49 lines
1.9 KiB
Markdown
49 lines
1.9 KiB
Markdown
---
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title: Receive Message
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hide_title: true
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---
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{/*##head##*/}
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# Receive Message
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**Receive Message** nodes are used to receive messages sent over MQTT, by a [**Send Message**](/library/modules/mqtt/send-message) node for example. Messages can be sent across devices and
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be used for inter-device communication and IoT. The **Receive Message** node subscribes to an MQTT topic and receives any message and payload published to that topic.
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{/*##head##*/}
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<div class = "node-inputs">
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## Inputs
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### Other
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**Topic**
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The topic name can be any identifier and is used by the **Receive Message** nodes to connect sender and receiver nodes, or publishers and subscribers in MQTT. Most commonly the topics are specified as a hierarchy with **/** as delimiters, e.g. `/Foo/Bar/1`. Sometimes the topics need to be dynamic, this can be achieved by encapsulating a topic component with curly brackets, e.g. `/Foo/{Bar}/1`. In this case a port called _Bar_ will show up.
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Topics on _Receive Message_ can also be specified with wildcards, so for instance `/Foo/+/Bar` will subscribe to both `/Foo/Hello/Bar` and `/Foo/Goodbye/Bar`.
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The exact topic component used when sending the message can be retrieved in a similar way to dynamic topics, by specifying `/Foo/+X+/Bar` an output port called _X_ will
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be created that will hold the value of the topic component when the message is received.
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**Enabled**
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Enable and disable the **Receive Message** node.
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</div>
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<div class = "node-outputs">
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## Outputs
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### PAYLOAD
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**Receive Message** nodes can have arbitrary output ports, payloads, that will assume the value of any incoming messages, for example a [Send Message](/library/modules/mqtt/send-message) node. These ports are referred to as payload ports.
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These ports can be added by inspecting the node and clicking the _Add port_ button in the _Payload_ section.
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**Received**
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A signal triggered when a message is received.
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</div>
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[0]: ./send-message
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