[TRA] Added Doxygen comments

src/protocols/TransportLayer.h

@@ -3,17 +3,83 @@
 
 #include "TypeDef.h"
 
+/*!
+  \class TransportLayer
+
+  \brief Provides common interface for protocols that run on modules with Internet connectivity, such as HTTP or MQTT.
+  Because this class is used mainly as interface, all of its virtual members must be implemented in the module class.
+*/
 class TransportLayer {
   public:
     // constructor
     // this class is purely virtual and does not require explicit constructor
-    
+
     // basic methods
+
+    /*!
+      \brief Open transport layer connection.
+
+      \param host Host to connect to.
+
+      \param protocol Transport protocol to use. Usually "TCP" or "UDP".
+
+      \param port to be used for the connection.
+
+      \param tcpKeepAlive TCP keep alive interval. Defaults to 0.
+
+      \returns \ref status_codes
+    */
     virtual int16_t openTransportConnection(const char* host, const char* protocol, uint16_t port, uint16_t tcpKeepAlive = 0) = 0;
+
+    /*!
+      \brief Close transport layer connection.
+
+      \returns \ref status_codes
+    */
     virtual int16_t closeTransportConnection() = 0;
+
+    /*!
+      \brief Send string-based data.
+
+      \param string String data to be sent.
+
+      \returns \ref status_codes
+    */
     virtual int16_t send(const char* data) = 0;
+
+    /*!
+      \brief Send arbitrary binary data.
+
+      \param data Data to be sent.
+
+      \param len Number of bytes to send.
+
+      \returns \ref status_codes
+    */
     virtual int16_t send(uint8_t* data, uint32_t len) = 0;
+
+    /*!
+      \brief Receive data.
+
+      \param data Pointer to array to save the received data.
+
+      \param len Number of bytes to read.
+
+      \param timeout Reception timeout in ms. Defaults to 10000.
+
+      \returns \ref status_codes
+    */
     virtual size_t receive(uint8_t* data, size_t len, uint32_t timeout = 10000) = 0;
+
+    /*!
+      \brief Get number of received bytes.
+
+      \param timeout Reception timeout in ms. Defaults to 10000.
+
+      \param minBytes Minimum required number of bytes that must be received.
+
+      \returns Number of received bytes, or 0 on timeout.
+    */
     virtual size_t getNumBytes(uint32_t timeout = 10000, size_t minBytes = 10) = 0;
 };