Initial idea

anscloud-common/include/anscloud/common/i_message_broker.h

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+#pragma once
+//=============================================================================
+// IMessageBroker - Abstract interface for message broker operations
+// 
+// Your existing RabbitMQ C++ API implements this interface.
+// The SDK (DeviceAgent / GatewayAgent) depends only on this abstraction,
+// not on any concrete AMQP library.
+//=============================================================================
+
+#ifndef ANSCLOUD_COMMON_I_MESSAGE_BROKER_H
+#define ANSCLOUD_COMMON_I_MESSAGE_BROKER_H
+
+#include <string>
+#include <functional>
+#include <memory>
+#include <cstdint>
+
+namespace anscloud {
+
+// Forward declare
+struct BrokerConfig;
+
+//-----------------------------------------------------------------------------
+// Message received from broker
+//-----------------------------------------------------------------------------
+struct BrokerMessage {
+    std::string exchange;
+    std::string routing_key;
+    std::string body;              // JSON payload
+    std::string correlation_id;    // For RPC matching
+    std::string reply_to;          // Reply queue/routing key
+    std::string message_id;
+    std::string content_type;      // "application/json"
+    uint64_t    delivery_tag = 0;
+    bool        redelivered = false;
+};
+
+//-----------------------------------------------------------------------------
+// Publish options
+//-----------------------------------------------------------------------------
+struct PublishOptions {
+    std::string correlation_id;
+    std::string reply_to;
+    std::string message_id;
+    std::string content_type = "application/json";
+    bool persistent = true;
+    int  expiration_ms = 0;        // 0 = no expiry (TTL)
+};
+
+//-----------------------------------------------------------------------------
+// Callback types
+//-----------------------------------------------------------------------------
+using MessageCallback     = std::function<void(const BrokerMessage& msg)>;
+using ConnectionCallback  = std::function<void(bool connected)>;
+using ErrorCallback       = std::function<void(const std::string& error)>;
+
+//=============================================================================
+// IMessageBroker - Pure virtual interface
+//
+// Your existing RabbitMQ C++ API creates a class that inherits from this:
+//
+//   class MyRabbitMQBroker : public anscloud::IMessageBroker {
+//       // ... implement all pure virtual methods using your existing API
+//   };
+//
+//=============================================================================
+class IMessageBroker {
+public:
+    virtual ~IMessageBroker() = default;
+
+    //--- Connection lifecycle ------------------------------------------------
+    virtual bool connect(const std::string& host, int port,
+                         const std::string& username, const std::string& password,
+                         const std::string& vhost) = 0;
+    virtual void disconnect() = 0;
+    virtual bool is_connected() const = 0;
+
+    //--- Exchange & Queue declarations (idempotent) --------------------------
+    virtual bool declare_exchange(const std::string& name,
+                                  const std::string& type = "topic",
+                                  bool durable = true) = 0;
+
+    virtual bool declare_queue(const std::string& name,
+                               bool durable = true,
+                               bool exclusive = false,
+                               bool auto_delete = false) = 0;
+
+    virtual bool bind_queue(const std::string& queue,
+                            const std::string& exchange,
+                            const std::string& routing_key) = 0;
+
+    //--- Publishing ----------------------------------------------------------
+    virtual bool publish(const std::string& exchange,
+                         const std::string& routing_key,
+                         const std::string& body,
+                         const PublishOptions& options = {}) = 0;
+
+    //--- Consuming -----------------------------------------------------------
+    // Start consuming from a queue. Messages delivered via callback.
+    // Returns a consumer tag (string) that can be used to cancel.
+    virtual std::string start_consuming(const std::string& queue,
+                                        MessageCallback callback,
+                                        bool auto_ack = true) = 0;
+
+    // Cancel a consumer by tag
+    virtual void cancel_consumer(const std::string& consumer_tag) = 0;
+
+    // Process pending messages (call from event loop).
+    // timeout_ms: max time to wait for messages. 0 = non-blocking poll.
+    // Returns number of messages processed.
+    virtual int process_messages(int timeout_ms = 100) = 0;
+
+    //--- Callbacks -----------------------------------------------------------
+    virtual void on_connected(ConnectionCallback cb) = 0;
+    virtual void on_error(ErrorCallback cb) = 0;
+};
+
+//=============================================================================
+// Factory function type - your application provides this
+//=============================================================================
+using BrokerFactory = std::function<std::unique_ptr<IMessageBroker>()>;
+
+} // namespace anscloud
+
+#endif // ANSCLOUD_COMMON_I_MESSAGE_BROKER_H