nrp_mqtt_client.h

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/* * NRP Core - Backend infrastructure to synchronize simulations
 *
 * Copyright 2020-2023 NRP Team
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * This project has received funding from the European Union’s Horizon 2020
 * Framework Programme for Research and Innovation under the Specific Grant
 * Agreement No. 945539 (Human Brain Project SGA3).
 */
 
#ifndef MQTT_CLIENT_H
#define MQTT_CLIENT_H
 
 
#include <functional>
 
#include "nlohmann/json.hpp"
 
#include "nrp_general_library/utils/nrp_logger.h"
#include "mqtt/async_client.h"
 
#define MQTT_BASE "nrp_simulation"
 
// TODO: QOS and non-clean session are hardcoded, they could be parameters
const int  QOS = 1;
const auto TIMEOUT = std::chrono::seconds(10);
 
class NRPMQTTClient;
 
// TODO: mqtt callbacks can also take care of handling disconnections with server, failed sending or receiving, etc.
//  As a future extension these possibilities can be explored further and added here.
class MQTTCallback : public virtual mqtt::callback {
    void message_arrived(mqtt::const_message_ptr msg) override;
 
public:
 
    MQTTCallback(NRPMQTTClient* proxy);
    NRPMQTTClient* _proxy;
};
 
class NRPMQTTClient {
 
public:
    NRPMQTTClient(nlohmann::json clientParams);
 
    NRPMQTTClient();
 
    virtual ~NRPMQTTClient() = default;
 
    virtual void subscribe(const std::string& address, const std::function<void (const std::string&)>& callback);
 
    virtual void publish(const std::string& address, const std::string& msg, bool retained=false);
 
    void publishDirect(const std::string& address, const std::string& msg);
 
    virtual void disconnect();
 
    virtual bool isConnected();
 
    virtual void clearRetained();
 
private:
 
    std::shared_ptr< mqtt::async_client> _mqttClient;
 
    std::map<std::string, mqtt::topic> _topics;
 
    std::map<std::string, std::function<void (const std::string&)>> _subscribers;
 
    MQTTCallback _callback;
 
    friend MQTTCallback;
};
 
#endif //MQTT_CLIENT_H