MQTT publish ，Does your topic contain '+' or '#'?

D:\Program Files (x86)\mosquitto>mosquitto_pub -t "iot-2/type/devicecbs1/id/+/evt/eid/fmt/json" -m alkjdklajdf

Error: Invalid input. Does your topic contain '+' or '#'?

Error: The connection was lost.

D:\Program Files (x86)\mosquitto>mosquitto_pub -t "iot-2/type/devicecbs1/id/a/evt/eid/fmt/json" -m 2374918324

D:\Program Files (x86)\mosquitto>mosquitto_pub -t "iot-2/type/devicecbs1/id/a/evt/eid/fmt/json" -m jaljdljakd

After modified the topic （delete the wildcard ‘+’ ）：

mqtt onPublic----------- :iot-2/type/devicecbs1/id/a/evt/eid/fmt/json

mqtt onPublic----------- :2374918324

mqtt save data ....onPublish 

----------------------------------saveToDB--------------------------------------- = 2374918324

save to cloudant DB succeeded!

----------------------------------saveToDB--------------------------------------- = null

----------------------------------saveToDB--------------------------------------- = null

----------------------------------saveToDB--------------------------------------- = null

----------------------------------saveToDB--------------------------------------- = null

mqtt onPublic----------- :iot-2/type/devicecbs1/id/a/evt/eid/fmt/json

mqtt onPublic----------- :jaljdljakd

mqtt save data ....onPublish 

----------------------------------saveToDB--------------------------------------- = jaljdljakd

save to cloudant DB succeeded!

Note:

subscribe topic可以有wildcard，publish topic不可以有wildcard！！

MQTT协议中只有两种wildcard，一个是+，一个是#。

使用/表示一种 层次结构，意思就是比如在一个小区里有很多的device或者sensor，小区是一个层次，小区里面的每一个单元是一个层次，每个单元里每一个家庭是一个层次，每个家庭的里面可能是厨房里有温度sensor，卧室里有湿度sensor，大厅里有红外探测device，MQTT就是将这些使用”左斜杠“进行分层的，进而表示到每一个device和sensor。