Support binary data (#104)

* Initial branch commit for supporting binary payloads
* Adds wrappers for transmitting binary data

examples/Esp32-lwmqtt/esp32-mqtt.h

@@ -89,10 +89,18 @@ void publishTelemetry(String data) {
   mqtt->publishTelemetry(data);
 }
 
+void publishTelemetry(const char* data, int length) {
+  mqtt->publishTelemetry(data, length);
+}
+
 void publishTelemetry(String subfolder, String data) {
   mqtt->publishTelemetry(subfolder, data);
 }
 
+void publishTelemetry(String subfolder, const char* data, int length) {
+  mqtt->publishTelemetry(subfolder, data, length);
+}
+
 void connect() {
   connectWifi();
   mqtt->mqttConnect();

examples/Esp8266-lwmqtt/esp8266_mqtt.h

@@ -116,10 +116,18 @@ void publishTelemetry(String data) {
   mqtt->publishTelemetry(data);
 }
 
+void publishTelemetry(const char* data, int length) {
+  mqtt->publishTelemetry(data, length);
+}
+
 void publishTelemetry(String subfolder, String data) {
   mqtt->publishTelemetry(subfolder, data);
 }
 
+void publishTelemetry(String subfolder, const char* data, int length) {
+  mqtt->publishTelemetry(subfolder, data, length);
+}
+
 void connect() {
   mqtt->mqttConnect();
 }

examples/MKR1000-lwmqtt/mkr1000-mqtt.h

@@ -81,19 +81,27 @@ void connectWifi() {
 ///////////////////////////////
 // Orchestrates various methods from preceeding code.
 ///////////////////////////////
-void connect() {
-  connectWifi();
-  mqtt->mqttConnect();
-}
-
 void publishTelemetry(String data) {
   mqtt->publishTelemetry(data);
 }
 
+void publishTelemetry(const char* data, int length) {
+  mqtt->publishTelemetry(data, length);
+}
+
 void publishTelemetry(String subfolder, String data) {
   mqtt->publishTelemetry(subfolder, data);
 }
 
+void publishTelemetry(String subfolder, const char* data, int length) {
+  mqtt->publishTelemetry(subfolder, data, length);
+}
+
+void connect() {
+  connectWifi();
+  mqtt->mqttConnect();
+}
+
 void setupCloudIoT() {
   device = new CloudIoTCoreDevice(
       project_id, location, registry_id, device_id,

examples/universal-lwmqtt/universal-mqtt.h

@@ -301,10 +301,18 @@ void publishTelemetry(String data) {
   mqtt->publishTelemetry(data);
 }
 
+void publishTelemetry(const char* data, int length) {
+  mqtt->publishTelemetry(data, length);
+}
+
 void publishTelemetry(String subfolder, String data) {
   mqtt->publishTelemetry(subfolder, data);
 }
 
+void publishTelemetry(String subfolder, const char* data, int length) {
+  mqtt->publishTelemetry(subfolder, data, length);
+}
+
 void connect() {
   mqtt->mqttConnect();
 }

src/CloudIoTCoreMqtt.cpp

@@ -15,7 +15,7 @@
 #include "CloudIoTCoreMqtt.h"
 
 // Forward global callback declarations
-String getJwt(); 
+String getJwt();
 void messageReceived(String &topic, String &payload);
 
 
@@ -42,15 +42,27 @@ void CloudIoTCoreMqtt::publishTelemetry(String data) {
   this->mqttClient->publish(device->getEventsTopic(), data);
 }
 
+void CloudIoTCoreMqtt::publishTelemetry(const char* data, int length) {
+  this->mqttClient->publish(device->getEventsTopic().c_str(), data, length);
+}
+
 void CloudIoTCoreMqtt::publishTelemetry(String subtopic, String data) {
   this->mqttClient->publish(device->getEventsTopic() + subtopic, data);
 }
 
+void CloudIoTCoreMqtt::publishTelemetry(String subtopic, const char* data, int length) {
+  this->mqttClient->publish(String(device->getEventsTopic() + subtopic).c_str(), data, length);
+}
+
 // Helper that just sends default sensor
 void CloudIoTCoreMqtt::publishState(String data) {
   this->mqttClient->publish(device->getStateTopic(), data);
 }
 
+void CloudIoTCoreMqtt::publishState(const char* data, int length) {
+  this->mqttClient->publish(device->getStateTopic().c_str(), data, length);
+}
+
 void CloudIoTCoreMqtt::onConnect() {
   if (logConnect) {
     publishState("connected");
@@ -170,7 +182,7 @@ void CloudIoTCoreMqtt::mqttConnect() {
   }
 
   // Set QoS to 1 (ack) for configuration messages
-  this->mqttClient->subscribe(device->getConfigTopic(), 1); 
+  this->mqttClient->subscribe(device->getConfigTopic(), 1);
   // QoS 0 (no ack) for commands
   this->mqttClient->subscribe(device->getCommandsTopic(), 0);
 

src/CloudIoTCoreMqtt.h

@@ -39,8 +39,11 @@ class CloudIoTCoreMqtt {
 
     void startMQTT();
     void publishTelemetry(String data);
+    void publishTelemetry(const char* data, int length);
     void publishTelemetry(String subtopic, String data);
+    void publishTelemetry(String subtopic, const char* data, int length);
     void publishState(String data);
+    void publishState(const char* data, int length);
     void onConnect();
     void setLogConnect(boolean enabled);
     void logError();