Add overloaded request method to node for non-blocking calls using ab…

…stract types.

- Add overloaded method to Node.
- Update specialisation of ReqHandler to handle callbacks using google::protobuf::Message.

Signed-off-by: Rhys Mainwaring <rhys.mainwaring@me.com>

include/gz/transport/Node.hh

@@ -561,6 +561,27 @@ namespace gz
           std::function<void(const ReplyT &_reply,
                              const bool _result)> &_callback);
 
+      /// \brief Request a new service using a non-blocking call.
+      /// In this version the callback is a lambda function and the
+      /// request and response may be abstract types.
+      /// \param[in] _topic Service name requested.
+      /// \param[in] _request Protobuf message containing the request's
+      /// parameters.
+      /// \param[in] _callback Lambda function executed when the response
+      /// arrives. The callback has the following parameters:
+      ///   * _reply Protobuf message containing the response.
+      ///   * _result Result of the service call. If false, there was
+      ///   a problem executing your request.
+      /// \param[in] _repType Message type used in the response.
+      /// \return true when the service call was succesfully requested.
+      public: template<typename RequestT, typename ReplyT>
+      bool Request(
+          const std::string &_topic,
+          const RequestT &_request,
+          std::function<void(const ReplyT &_reply,
+                             const bool _result)> &_callback,
+          const char *_repType);
+
       /// \brief Request a new service without input parameter using a
       /// non-blocking call.
       /// In this version the callback is a lambda function.

include/gz/transport/ReqHandler.hh

@@ -32,6 +32,8 @@
 #include <memory>
 #include <string>
 
+#include <gz/msgs/Factory.hh>
+
 #include "gz/transport/config.hh"
 #include "gz/transport/Export.hh"
 #include "gz/transport/TransportTypes.hh"
@@ -318,6 +320,43 @@ namespace gz
       {
       }
 
+      /// \brief Create a specific protobuf message given its serialized data.
+      /// \param[in] _data The serialized data.
+      /// \return Pointer to the specific protobuf message.
+      public: std::shared_ptr<google::protobuf::Message>
+      CreateMsg(const std::string &_data) const
+      {
+        // Instantiate a specific protobuf message
+        std::shared_ptr<google::protobuf::Message> msgPtr =
+            gz::msgs::Factory::New(this->RepTypeName());
+        if (!msgPtr)
+        {
+          std::cerr << "Unable to create response of type["
+                    << this->RepTypeName() << "].\n";
+          return nullptr;
+        }
+
+        // Create the message using some serialized data
+        if (!msgPtr->ParseFromString(_data))
+        {
+          std::cerr << "ReqHandler::CreateMsg() error: ParseFromString failed"
+                    << std::endl;
+        }
+
+        return msgPtr;
+      }
+
+      /// \brief Set the callback for this handler.
+      /// \param[in] _cb The callback with the following parameters:
+      /// * _rep Protobuf message containing the service response.
+      /// * _result True when the service request was successful or
+      /// false otherwise.
+      public: void SetCallback(const std::function <void(
+        const google::protobuf::Message &_rep, const bool _result)> &_cb)
+      {
+        this->cb = _cb;
+      }
+
       /// \brief Set the REQ protobuf message for this handler.
       /// \param[in] _reqMsg Protofub message containing the input parameters of
       /// of the service request.
@@ -371,8 +410,25 @@ namespace gz
       // Documentation inherited.
       public: void NotifyResult(const std::string &_rep, const bool _result)
       {
-        this->rep = _rep;
-        this->result = _result;
+        // Execute the callback (if existing).
+        if (this->cb)
+        {
+          // Instantiate the specific protobuf message associated to this topic.
+          auto msg = this->CreateMsg(_rep);
+          if (!msg)
+          {
+            /// \todo(srmainwaring) verify this is the correct fail behaviour
+            this->result = false;
+            this->repAvailable = false;
+            this->condition.notify_one();
+          }
+          this->cb(*msg, _result);
+        }
+        else
+        {
+          this->rep = _rep;
+          this->result = _result;
+        }
 
         this->repAvailable = true;
         this->condition.notify_one();
@@ -409,6 +465,14 @@ namespace gz
 
       /// \brief Protobuf message containing the response.
       private: google::protobuf::Message *repMsg = nullptr;
+
+      /// \brief Callback to the function registered for this handler with the
+      /// following parameters:
+      /// \param[in] _rep Protobuf message containing the service response.
+      /// \param[in] _result True when the service request was successful or
+      /// false otherwise.
+      private: std::function<void(
+          const google::protobuf::Message &_rep, const bool _result)> cb;
     };
     }
   }

include/gz/transport/detail/Node.hh

@@ -477,6 +477,99 @@ namespace gz
       return true;
     }
 
+    //////////////////////////////////////////////////
+    template<typename RequestT, typename ReplyT>
+    bool Node::Request(
+      const std::string &_topic,
+      const RequestT &_request,
+      std::function<void(const ReplyT &_reply, const bool _result)> &_cb,
+      const char *_repType)
+    {
+      auto rep = gz::msgs::Factory::New(_repType);
+      if (!rep)
+      {
+        std::cerr << "Unable to create response of type["
+                  << _repType << "].\n";
+        return false;
+      }
+
+      // Topic remapping.
+      std::string topic = _topic;
+      this->Options().TopicRemap(_topic, topic);
+
+      std::string fullyQualifiedTopic;
+      if (!TopicUtils::FullyQualifiedName(this->Options().Partition(),
+        this->Options().NameSpace(), topic, fullyQualifiedTopic))
+      {
+        std::cerr << "Service [" << topic << "] is not valid." << std::endl;
+        return false;
+      }
+
+      bool localResponserFound;
+      IRepHandlerPtr repHandler;
+      {
+        std::lock_guard<std::recursive_mutex> lk(this->Shared()->mutex);
+        localResponserFound = this->Shared()->repliers.FirstHandler(
+              fullyQualifiedTopic,
+              _request.GetTypeName(),
+              rep->GetTypeName(),
+              repHandler);
+      }
+
+      // If the responser is within my process.
+      if (localResponserFound)
+      {
+        // There is a responser in my process, let's use it.
+        bool result = repHandler->RunLocalCallback(_request, *rep);
+
+        _cb(*rep, result);
+        return true;
+      }
+
+      // Create a new request handler.
+      std::shared_ptr<ReqHandler<RequestT, ReplyT>> reqHandlerPtr(
+        new ReqHandler<RequestT, ReplyT>(this->NodeUuid()));
+
+      // Insert the request's parameters.
+      reqHandlerPtr->SetMessage(&_request);
+
+      // Set the response message (to set the type info).
+      reqHandlerPtr->SetResponse(rep.get());
+
+      // Insert the callback into the handler.
+      reqHandlerPtr->SetCallback(_cb);
+
+      {
+        std::lock_guard<std::recursive_mutex> lk(this->Shared()->mutex);
+
+        // Store the request handler.
+        this->Shared()->requests.AddHandler(
+          fullyQualifiedTopic, this->NodeUuid(), reqHandlerPtr);
+
+        // If the responser's address is known, make the request.
+        SrvAddresses_M addresses;
+        if (this->Shared()->TopicPublishers(fullyQualifiedTopic, addresses))
+        {
+          this->Shared()->SendPendingRemoteReqs(fullyQualifiedTopic,
+            _request.GetTypeName(), rep->GetTypeName());
+        }
+        else
+        {
+          // Discover the service responser.
+          if (!this->Shared()->DiscoverService(fullyQualifiedTopic))
+          {
+            std::cerr << "Node::Request(): Error discovering service ["
+                      << topic
+                      << "]. Did you forget to start the discovery service?"
+                      << std::endl;
+            return false;
+          }
+        }
+      }
+
+      return true;
+    }
+
     //////////////////////////////////////////////////
     template<typename ReplyT>
     bool Node::Request(