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Communication Protocol Characteristics (Handlers)

Java (experimental)

Uses Java methods to supply values (receive) and for callbacks (send).

  • Protocol identifier: java
  • URI scheme: java://<ignored-host>[:ignored-port]/<topic>
    • the value for host and port are always ignored, but are necessary to form a legal URI
  • No required runtime dependencies
  • Receive behaviour: Use the generated method ragconnectJavaPush to pass a value to the receiving port.
  • Send behaviour: When the value to be sent changes, previously registered callbacks are invoked.
  • Additional remarks:
    • First leading slash not included in topic.
    • Currently, the default mappings are applied, which requires a consumer to expect byte[] (instead of a more intuitive token or node value). This might change in future versions.

MQTT

Use an MQTT broker to receive and send messages.

  • Protocol identifier: mqtt
  • URI scheme: mqtt://<broker-host>[:port]/<topic>
  • Default port: 1883
  • Type for mapping definitions: byte[]
  • Required runtime dependencies:
    • group: 'org.fusesource.mqtt-client', name: 'mqtt-client', version: '1.15'
  • Receive behaviour: Upon connection, instruct the MQTT broker to listen for messages on some topic and pass the value of those messages to the receiving port.
  • Send behaviour: When the value to be sent changes, publish a message to the topic specified upon connection.
  • Additional remarks:
    • First leading slash not included in topic.
    • Mqtt is selected by default, so this dependency therefore is required "by default".
    • Might work with other versions of org.fusesource.mqtt-client.mqtt.client as well.

REST Server

Create a new REST server with its own target routes.

  • Protocol identifier: rest
  • URI scheme: rest://localhost[:port]/<path>
  • Default port: 4567
  • Type for mapping definitions: byte[]
  • Required runtime dependencies:
    • group: 'com.sparkjava', name: 'spark-core', version: '2.9.3'
  • Receive behaviour: Upon connection, create a new PUT connection and pass the value of every call to this PUT route to the receiving port.
  • Send behaviour: Upon connection, create a new GET connection and serve the latest value at this GET route.
  • Additional remarks:
    • Host is always localhost.
    • Targets to be invoked need to replace rest with http
    • Might work with newer versions of com.sparkjava.spark-core as well.
    • For debugging, it is beneficial to include an implementation for SLF4J.

REST Client

Invoke REST routes to fetch and send values.

  • Protocol identifier: restClient
  • URI scheme: restClient://localhost[:port]/<path>
  • Default port: 80
  • Type for mapping definitions: byte[]
  • No required runtime dependencies
  • Receive behaviour: Whenever the accessor is called, a GET request fetches the latest data and returns this data.
  • Send behaviour: When the value to be sent changes, a PUT request sends this data.
  • Additional remarks:
    • Invoked target replaces restClient with http
    • Important constraint: Receiving ports are only supported for tokens, since they interrupt the getter method!
Last update: July 28, 2023 16:46:53