Payload for the MQTT message
As with all other transports, the translation between EPL events and MQTT payloads is based on the choice of host plug-in and codecs. See
Host plug-ins and configuration and
Codec Connectivity Plug-ins for further information.
The payload for the MQTT message is a byte array. Therefore, the String codec should usually be used to convert a byte[] (Java) or buffer_t (C++) type payload into a hostward string event. The same String codec can also be used to convert a string event to a transportward message with a byte[] or buffer_t type.
The following is a simple example of a YAML configuration file where the payload of the MQTT message will be the string form of the Apama event:
connectivityPlugins:
mqttTransport:
libraryName: connectivity-mqtt
class: MQTTTransport
stringCodec:
libraryName: connectivity-string-codec
class: StringCodec
dynamicChainManagers:
mqttManager:
transport: mqttTransport
managerConfig:
brokerURL: tcp://localhost:1883
dynamicChains:
mqttChain:
- apama.eventString:
suppressLoopback: true
- stringCodec
- mqttTransport