refactor: remove 60+ deprecated network interfaces, adapters, and metrics (#879)

* refactor: remove 60+ deprecated network interfaces, adapters, and metrics

Remove deprecated items across 7 categories:

- Un-deprecate 28 callback observer methods (set_receive/connected/
  disconnected/error_callback) across client interfaces and tcp_socket
- Clean 12 legacy messaging class deprecation warnings and directives
- Un-deprecate no_tls policy (still used as template default)
- Delete 6 protocol-specific public interface headers (i_quic/udp/
  websocket_client/server.h); remove NETWORK_INCLUDE_DEPRECATED_INTERFACES
- Un-deprecate 5 adapter classes (common_thread_pool/logger/monitoring,
  thread_system_pool_adapter, bind_thread_system_pool_into_manager)
- Remove performance_metrics struct and get_performance_metrics() from
  messaging_bridge; replace with private impl::internal_metrics
- Remove BUILD_WITH_MONITORING_SYSTEM CMake option and related
  integration setup; clean all deprecation suppression macros

* fix(cmake): remove leftover monitoring_system references

The previous commit removed the find_monitoring_system() and
setup_monitoring_system_integration() function definitions but
left behind their call sites, causing CMake configuration to fail
with "Unknown CMake command" on all platforms.

* fix(libs): update library wrappers to use generic protocol interfaces

The QUIC and WebSocket library wrapper headers still referenced the
deleted protocol-specific public interface headers (i_quic_client.h,
i_quic_server.h, i_websocket_client.h, i_websocket_server.h). Update
them to use the generic i_protocol_client.h and i_protocol_server.h
interfaces instead.

Author: kcenon

.github/workflows/ci.yml

@@ -41,7 +41,6 @@ jobs:
           -DBUILD_WITH_LOGGER_SYSTEM=OFF \
           -DBUILD_WITH_THREAD_SYSTEM=OFF \
           -DBUILD_WITH_CONTAINER_SYSTEM=OFF \
-          -DBUILD_WITH_MONITORING_SYSTEM=OFF \
           -DBUILD_TESTS=OFF \
           -DBUILD_EXAMPLES=OFF \
           -DBUILD_SAMPLES=OFF

CMakeLists.txt

@@ -87,10 +87,6 @@ option(BUILD_WITH_LOGGER_SYSTEM "Build with logger_system integration (OPTIONAL
 # Optional dependencies
 option(BUILD_WITH_CONTAINER_SYSTEM "Build with container_system integration" ON)
 
-# DEPRECATED: Since issue #342, monitoring integration uses EventBus pattern
-# instead of compile-time dependency. This option is kept for backward
-# compatibility but has no effect. It will be removed in a future version.
-option(BUILD_WITH_MONITORING_SYSTEM "DEPRECATED - monitoring uses EventBus pattern (no compile-time dep)" OFF)
 
 # Official gRPC library integration (issue #360)
 # When enabled, wraps the official grpc++ library for production use.
@@ -119,19 +115,6 @@ else()
     message(STATUS "logger_system integration is DISABLED (default - uses common_system's ILogger)")
 endif()
 
-# Monitoring integration status message
-# Note: Since issue #342, monitoring uses EventBus pattern - no compile-time dependency
-if(BUILD_WITH_MONITORING_SYSTEM)
-    message(STATUS "")
-    message(STATUS "========================================")
-    message(STATUS "BUILD_WITH_MONITORING_SYSTEM is DEPRECATED")
-    message(STATUS "")
-    message(STATUS "Since issue #342, network_system uses EventBus-based metric")
-    message(STATUS "publishing. No compile-time monitoring_system dependency needed.")
-    message(STATUS "External consumers subscribe to network_metric_event via EventBus.")
-    message(STATUS "========================================")
-    message(STATUS "")
-endif()
 message(STATUS "Monitoring: EventBus-based metric publishing (no compile-time dependency)")
 
 # Respect global BUILD_INTEGRATION_TESTS flag if set

benchmarks/CMakeLists.txt

@@ -68,9 +68,6 @@ if(benchmark_FOUND OR BENCHMARK_FOUND)
         target_compile_definitions(network_benchmarks PRIVATE BUILD_MESSAGING_BRIDGE)
     endif()
 
-    # Suppress deprecation warnings for benchmark access to internal APIs
-    target_compile_definitions(network_benchmarks PRIVATE NETWORK_SYSTEM_SUPPRESS_DEPRECATION_WARNINGS)
-
     target_compile_features(network_benchmarks PRIVATE cxx_std_20)
 
     if(CMAKE_CXX_COMPILER_ID MATCHES "GNU|Clang")

cmake/NetworkSystemDependencies.cmake

@@ -562,108 +562,6 @@ function(find_common_system)
     endif()
 endfunction()
 
-##################################################
-# Find monitoring_system
-##################################################
-function(find_monitoring_system)
-    if(NOT BUILD_WITH_MONITORING_SYSTEM)
-        return()
-    endif()
-
-    message(STATUS "Looking for monitoring_system...")
-
-    foreach(_candidate monitoring_system MonitoringSystem)
-        if(TARGET ${_candidate})
-            message(STATUS "Found monitoring_system CMake target: ${_candidate}")
-            set(MONITORING_SYSTEM_FOUND TRUE PARENT_SCOPE)
-            set(MONITORING_SYSTEM_TARGET ${_candidate} PARENT_SCOPE)
-            return()
-        endif()
-    endforeach()
-
-    # Check for existing CMake targets first
-    if(TARGET monitoring_system)
-        message(STATUS "Found monitoring_system as existing target")
-        set(MONITORING_SYSTEM_FOUND TRUE PARENT_SCOPE)
-        set(MONITORING_SYSTEM_TARGET monitoring_system PARENT_SCOPE)
-        return()
-    endif()
-
-    if(TARGET MonitoringSystem)
-        message(STATUS "Found MonitoringSystem as existing target")
-        set(MONITORING_SYSTEM_FOUND TRUE PARENT_SCOPE)
-        set(MONITORING_SYSTEM_TARGET MonitoringSystem PARENT_SCOPE)
-        return()
-    endif()
-
-    # Prioritize environment variable, then standard paths
-    set(_monitoring_search_paths)
-    set(_monitoring_lib_paths)
-
-    # 1. Check environment variable
-    if(DEFINED ENV{MONITORING_SYSTEM_ROOT})
-        list(APPEND _monitoring_search_paths "$ENV{MONITORING_SYSTEM_ROOT}/include" "$ENV{MONITORING_SYSTEM_ROOT}/sources")
-        list(APPEND _monitoring_lib_paths "$ENV{MONITORING_SYSTEM_ROOT}/build/lib")
-    endif()
-
-    # 2. Check CMake variable
-    if(DEFINED MONITORING_SYSTEM_ROOT)
-        list(APPEND _monitoring_search_paths "${MONITORING_SYSTEM_ROOT}/include" "${MONITORING_SYSTEM_ROOT}/sources")
-        list(APPEND _monitoring_lib_paths "${MONITORING_SYSTEM_ROOT}/build/lib")
-    endif()
-
-    # 3. Standard search paths
-    list(APPEND _monitoring_search_paths
-        "${CMAKE_CURRENT_SOURCE_DIR}/../monitoring_system/include"
-        "${CMAKE_CURRENT_SOURCE_DIR}/../monitoring_system/sources"
-        "${CMAKE_SOURCE_DIR}/monitoring_system/include"
-        "${CMAKE_SOURCE_DIR}/monitoring_system/sources"
-        "${CMAKE_SOURCE_DIR}/../monitoring_system/include"
-        "${CMAKE_SOURCE_DIR}/../monitoring_system/sources"
-        "../monitoring_system/include"
-        "../monitoring_system/sources"
-    )
-
-    list(APPEND _monitoring_lib_paths
-        "${CMAKE_CURRENT_SOURCE_DIR}/../monitoring_system/build/lib"
-        "${CMAKE_SOURCE_DIR}/monitoring_system/build/lib"
-        "${CMAKE_SOURCE_DIR}/../monitoring_system/build/lib"
-        "../monitoring_system/build/lib"
-    )
-
-    # Look for monitoring headers
-    find_path(MONITORING_SYSTEM_INCLUDE_DIR
-        NAMES kcenon/monitoring/core/performance_monitor.h monitoring/core/performance_monitor.h
-        PATHS ${_monitoring_search_paths}
-        NO_DEFAULT_PATH
-    )
-
-    if(MONITORING_SYSTEM_INCLUDE_DIR)
-        message(STATUS "Found monitoring_system at: ${MONITORING_SYSTEM_INCLUDE_DIR}")
-
-        find_library(MONITORING_SYSTEM_LIBRARY
-            NAMES monitoring_system MonitoringSystem
-            PATHS ${_monitoring_lib_paths}
-            PATH_SUFFIXES Debug Release
-            NO_DEFAULT_PATH
-        )
-
-        if(MONITORING_SYSTEM_LIBRARY)
-            message(STATUS "Found monitoring_system library: ${MONITORING_SYSTEM_LIBRARY}")
-        else()
-            message(WARNING "monitoring_system headers found but library not found")
-        endif()
-
-        set(MONITORING_SYSTEM_FOUND TRUE PARENT_SCOPE)
-        set(MONITORING_SYSTEM_INCLUDE_DIR ${MONITORING_SYSTEM_INCLUDE_DIR} PARENT_SCOPE)
-        set(MONITORING_SYSTEM_LIBRARY ${MONITORING_SYSTEM_LIBRARY} PARENT_SCOPE)
-    else()
-        message(WARNING "monitoring_system not found, integration disabled")
-        set(BUILD_WITH_MONITORING_SYSTEM OFF PARENT_SCOPE)
-        set(MONITORING_SYSTEM_FOUND FALSE PARENT_SCOPE)
-    endif()
-endfunction()
-
 ##################################################
 # Find gRPC library (optional - for NETWORK_ENABLE_GRPC_OFFICIAL)
 #
@@ -792,7 +690,6 @@ function(find_network_system_dependencies)
     find_container_system()
     find_thread_system()
     find_logger_system()
-    find_monitoring_system()
     find_common_system()
     find_grpc_library()
 
@@ -818,11 +715,6 @@ function(find_network_system_dependencies)
     set(LOGGER_SYSTEM_INCLUDE_DIR ${LOGGER_SYSTEM_INCLUDE_DIR} PARENT_SCOPE)
     set(LOGGER_SYSTEM_LIBRARY ${LOGGER_SYSTEM_LIBRARY} PARENT_SCOPE)
 
-    set(MONITORING_SYSTEM_FOUND ${MONITORING_SYSTEM_FOUND} PARENT_SCOPE)
-    set(MONITORING_SYSTEM_INCLUDE_DIR ${MONITORING_SYSTEM_INCLUDE_DIR} PARENT_SCOPE)
-    set(MONITORING_SYSTEM_LIBRARY ${MONITORING_SYSTEM_LIBRARY} PARENT_SCOPE)
-    set(MONITORING_SYSTEM_TARGET ${MONITORING_SYSTEM_TARGET} PARENT_SCOPE)
-
     set(COMMON_SYSTEM_FOUND ${COMMON_SYSTEM_FOUND} PARENT_SCOPE)
     set(COMMON_SYSTEM_INCLUDE_DIR ${COMMON_SYSTEM_INCLUDE_DIR} PARENT_SCOPE)
 
@@ -840,7 +732,6 @@ function(find_network_system_dependencies)
     set(BUILD_WITH_CONTAINER_SYSTEM ${BUILD_WITH_CONTAINER_SYSTEM} PARENT_SCOPE)
     set(BUILD_WITH_THREAD_SYSTEM ${BUILD_WITH_THREAD_SYSTEM} PARENT_SCOPE)
     set(BUILD_WITH_LOGGER_SYSTEM ${BUILD_WITH_LOGGER_SYSTEM} PARENT_SCOPE)
-    set(BUILD_WITH_MONITORING_SYSTEM ${BUILD_WITH_MONITORING_SYSTEM} PARENT_SCOPE)
     set(BUILD_WITH_COMMON_SYSTEM ${BUILD_WITH_COMMON_SYSTEM} PARENT_SCOPE)
     set(NETWORK_ENABLE_GRPC_OFFICIAL ${NETWORK_ENABLE_GRPC_OFFICIAL} PARENT_SCOPE)
 

cmake/NetworkSystemIntegration.cmake

@@ -166,21 +166,6 @@ function(setup_logger_system_integration target)
     endif()
 endfunction()
 
-##################################################
-# Configure monitoring_system integration
-# DEPRECATED: Since issue #342, monitoring uses EventBus pattern
-# This function is kept for backward compatibility but has no effect.
-##################################################
-function(setup_monitoring_system_integration target)
-    # DEPRECATED: No compile-time monitoring_system dependency needed
-    # Metrics are published via common_system's EventBus
-    # External consumers subscribe to network_metric_event
-    if(BUILD_WITH_MONITORING_SYSTEM)
-        message(STATUS "NOTE: BUILD_WITH_MONITORING_SYSTEM is deprecated")
-        message(STATUS "      Monitoring uses EventBus pattern - no compile-time dependency")
-    endif()
-endfunction()
-
 ##################################################
 # Configure common_system integration
 ##################################################
@@ -224,7 +209,6 @@ function(setup_network_system_integrations target)
     setup_container_system_integration(${target})
     setup_thread_system_integration(${target})
     setup_logger_system_integration(${target})
-    setup_monitoring_system_integration(${target})
     setup_common_system_integration(${target})
 
     # Platform-specific libraries

docs/INTEGRATION.md

@@ -185,18 +185,9 @@ The logger integration provides two implementations:
 
 ## Monitoring System Integration
 
-Provides metrics collection and observability capabilities.
+Provides metrics collection and observability capabilities via EventBus-based metric publishing.
 
-**Important**: This integration is **OPTIONAL** (OFF by default) to prevent circular dependencies with monitoring_system.
-
-### Configuration
-```cmake
-cmake .. -DBUILD_WITH_MONITORING_SYSTEM=ON
-```
-
-### Why Optional?
-
-monitoring_system (Tier 3) can optionally depend on network_system (Tier 4) for HTTP metrics export. Making monitoring_system a required dependency would create a circular dependency. Both integrations are optional and use adapter patterns to avoid compile-time cycles.
+No compile-time monitoring_system dependency is needed. External consumers subscribe to `network_metric_event` via EventBus.
 
 ### Features
 - **Counter metrics**: Track connection counts, bytes transferred
@@ -229,25 +220,6 @@ monitor.report_health("connection_1",
     0.0);   // packet_loss_rate
 ```
 
-### Implementation Details
-
-Two implementations are provided:
-
-1. **basic_monitoring**: Standalone mode (default)
-   - Used when BUILD_WITH_MONITORING_SYSTEM is OFF
-   - Logs metrics to console via logger_system
-   - No external dependencies
-
-2. **monitoring_system_adapter**: Integration mode
-   - Used when BUILD_WITH_MONITORING_SYSTEM is ON
-   - Full monitoring_system integration
-   - Uses performance_monitor and health_monitor
-
-### Requirements
-- When BUILD_WITH_MONITORING_SYSTEM=ON:
-  - monitoring_system must be built first (Tier 3)
-  - Headers at `../monitoring_system/include`
-
 For detailed documentation, see [integration/with-monitoring.md](integration/with-monitoring.md).
 
 ## Build Configuration
@@ -258,8 +230,7 @@ cmake .. -G Ninja \
     -DCMAKE_BUILD_TYPE=Release \
     -DBUILD_WITH_THREAD_SYSTEM=ON \
     -DBUILD_WITH_CONTAINER_SYSTEM=ON \
-    -DBUILD_WITH_LOGGER_SYSTEM=ON \
-    -DBUILD_WITH_MONITORING_SYSTEM=ON  # Optional
+    -DBUILD_WITH_LOGGER_SYSTEM=ON
 ```
 
 ### Minimal Build (No External Dependencies)
@@ -310,7 +281,6 @@ The system provides macros to check which integrations are available:
 - `BUILD_WITH_THREAD_SYSTEM` — enable thread pool integration via `thread_integration_manager`.
 - `BUILD_WITH_CONTAINER_SYSTEM` — enable container adapters via `container_manager`.
 - `BUILD_WITH_LOGGER_SYSTEM` — use `logger_system_adapter`; otherwise falls back to `basic_logger`.
-- `BUILD_WITH_MONITORING_SYSTEM` — use `monitoring_system_adapter`; otherwise falls back to `basic_monitoring` (OFF by default).
 
 ## Versioning & Dependencies
 

docs/integration/with-monitoring.md

@@ -289,11 +289,9 @@ No special build flags required for metric publishing. Metrics are always publis
 ```bash
 cmake .. -G Ninja \
     -DCMAKE_BUILD_TYPE=Release
-# That's it! No BUILD_WITH_MONITORING_SYSTEM needed
+# No special CMake flags needed for monitoring integration
 ```
 
-**Note**: `BUILD_WITH_MONITORING_SYSTEM` is deprecated and has no effect.
-
 ## Requirements
 
 - common_system (provides EventBus)

docs/refactoring/README.md

@@ -128,9 +128,6 @@ Explicitly include internal headers if absolutely necessary:
 ### Q: What if I need direct access to implementations?
 **A**: Most use cases are covered by facade API. If not, please open an issue describing your use case.
 
-### Q: How do I suppress deprecation warnings?
-**A**: Define `NETWORK_SYSTEM_SUPPRESS_DEPRECATION_WARNINGS` (but you should migrate instead).
-
 ## Contributing
 
 If you're contributing to this refactoring:

include/kcenon/network/detail/session/messaging_session.h

@@ -163,8 +163,6 @@ namespace kcenon::network::session
 		/*!
 		 * \brief Checks if the session has been stopped.
 		 * \return true if the session is stopped, false otherwise.
-		 *
-		 * \deprecated Use is_connected() instead (returns opposite value).
 		 */
 		[[nodiscard]] auto is_stopped() const noexcept -> bool {
 			return is_stopped_.load(std::memory_order_relaxed);
@@ -182,7 +180,6 @@ namespace kcenon::network::session
 		 * - Data is moved (not copied) to avoid memory allocation overhead.
 		 * - After calling this function, the original vector will be empty.
 		 *
-		 * \deprecated Use send() instead for Result-based error handling.
 		 */
 		auto send_packet(std::vector<uint8_t>&& data) -> void;
 

include/kcenon/network/experimental/README.md

@@ -51,5 +51,5 @@ This change is part of EPIC #577 to:
 ## See Also
 
 - `kcenon/network/facade/quic_facade.h` - Recommended facade API
-- `kcenon/network/interfaces/i_quic_client.h` - Public interface
-- `kcenon/network/interfaces/i_quic_server.h` - Public interface
+- `kcenon/network/interfaces/i_client.h` - Client interface
+- `kcenon/network/interfaces/i_server.h` - Server interface