MQTT-SN over UDP and XBee

Updated Gateway has been contributed to paho.
Latest Gateway can connect to AWS IoT.
https://github.com/eclipse/paho.mqtt-sn.embedded-c/tree/gateway

• MQTT-SN Gateway over XBee or UDP (running on linux)
• MQTT-SN Client over XBee (running on linux, Arduino and mbed)
• MQTT-SN Client over UDP (running on linux and Arduino)

AsyncMQTT-SN is available. https://github.com/ty4tw/AsyncMQTT-SN

Supported functions

• QOS Level 0 and 1
• SEARCHGW, GWINFO
• CONNECT, WILLTOPICREQ, WILLTOPIC, WILLMSGREQ, WILLMSG
• PINGREQ, PINGRESP
• CONNACK, REGISTER, REGACK, SUBACK, PUBACK, UNSUBACK
• SUBSCRIBE, PUBLISH, UNSUBSCRIBE, DISCONNECT

Implemented control flows:
Application program executes PUBLISH() function,
Protocol flow as berrow is conducted automaticaly.

             Client              Gateway               Broker
                |                   |                    |      
   PUBLISH() -->| --- SERCHGW ----> |                    |  
                | <-- GWINFO  ----- |                    |  
                | --- CONNECT ----> |                    |  
                | <--WILLTOPICREQ-- |                    |  
                | --- WILLTOPIC --> |                    |  
                | <-- WILLMSGREQ -- |                    |  
                | --- WILLMSG ----> | ---- CONNECT ----> |(accepted)     
                | <-- CONNACK ----- | <--- CONNACK ----- |   
                | --- PUBLISH ----> |                    |  
                | <-- PUBACK  ----- | (invalid TopicId)  |  
                | --- REGISTER ---> |                    |  
                | <-- REGACK  ----- |                    |  
                | --- PUBLISH ----> | ---- PUBLISH ----> |(accepted)  
                | <-- PUBACK  ----- | <---- PUBACK ----- |    
                |                   |                    |    
                //                  //                   //      
                |                   |                    |          
 SUBSCRIBE() -->| --- SUBSCRIBE --> | ---- SUBSCRIBE --> |     
 [set Callback] | <-- SUBACK ------ | <--- SUBACK ------ |    
                |                   |                    |    
                //                  //                   //    
                |                   |                    |    
                | <-- REGISTER ---- | <--- PUBLISH ----- |<-- PUBLISH  
[exec Callback] | <-- PUBLISH  ---- |                    |  
                | --- PUBACK   ---> | ---- PUBACK  ----> |--> PUBACK  
                |                   |                    |  

License

This source code is available under the BSD license