Support loading add-on configurations

score/mw/com/api_surface.lock.json

@@ -37,6 +37,18 @@
       "kind": "function",
       "signature": "InitializeRuntime : void (const RuntimeConfiguration &)"
     },
+    {
+      "name": "InitializeRuntimeAddonConfiguration",
+      "qualified_name": "score::mw::com::runtime::InitializeRuntimeAddonConfiguration",
+      "kind": "function",
+      "signature": "InitializeRuntimeAddonConfiguration : Result<void> (const RuntimeConfiguration &)"
+    },
+    {
+      "name": "InitializeRuntimeAddonConfiguration",
+      "qualified_name": "score::mw::com::runtime::InitializeRuntimeAddonConfiguration",
+      "kind": "function",
+      "signature": "InitializeRuntimeAddonConfiguration : Result<void> (score::json::Any)"
+    },
     {
       "name": "RuntimeConfiguration",
       "qualified_name": "score::mw::com::runtime::RuntimeConfiguration",

score/mw/com/doc/user_facing_API_examples.md

@@ -16,6 +16,7 @@ This document contains examples of each mw::com user facing API.
 | [`RuntimeConfiguration(argc, argv)`](#example-3-using-runtimeconfiguration-for-configuration-management) |
 | [`RuntimeConfiguration(Path)`](#example-3-using-runtimeconfiguration-for-configuration-management) |
 | [`RuntimeConfiguration::GetConfigurationPath()`](#example-3-using-runtimeconfiguration-for-configuration-management) |
+| [`RuntimeConfiguration::InitializeRuntimeAddonConfiguration()`](#example-4-using-initializeruntimeaddonconfiguration-to-load-additional-mwcom-configurations) |
 | **Data Types** |
 | [`InstanceIdentifier::Create()`](#example-1-using-instanceidentifier-for-service-instance-management) |
 | [`InstanceIdentifier::ToString()`](#example-1-using-instanceidentifier-for-service-instance-management) |
@@ -274,6 +275,47 @@ const auto& config_path = default_config.GetConfigurationPath();
 
 ---
 
+
+### Example 4: Using `InitializeRuntimeAddonConfiguration` to load additional `mw::com` configurations
+
+`Runtime` provides the APIs `InitializeRuntimeAddonConfiguration(RuntimeConfiguration&)` and `InitializeRuntimeAddonConfiguration(score::json::Any)`
+to load additional configurations. For example, this can be used by libraries that also rely on mw::com to load their
+configuration in addition to the application's configuration. It is assumed that prior to that call a complete mw::com configuration has been
+loaded via `InitializeRuntime()`. If not this call will cause an application termination.
+Add-on configurations will be merged into the existing configuration. Merge conflicts due to duplicate service type
+and service instance definitions will lead to an application termination. Add-on configurations are not supposed to contain a `global configuration`
+but only contains additional service types and service instances.
+In all cases of application termination, the error message will indicate the reason for the termination.
+
+<details>
+
+```cpp
+#include "score/mw/com/runtime.h"
+
+int main(int argc, char* argv[]) {
+    // Initialize mw::com runtime with command line arguments
+    score::mw::com::runtime::InitializeRuntime(argc, argv);
+
+    // Load additional add-on configuration
+    score::mw::com::runtime::RuntimeConfiguration addon_config{"/path/to/addon/mw_com_addon_config.json"};
+    score::mw::com::runtime::InitializeAddOnConfiguration(addon_config); 
+
+    // If no error occurred the application will reach this point and the configuration will be updated
+
+    return 0;
+}
+```
+
+#### Key Points
+- Configurations will be merged into the existing configuration
+- If no (complete) configuration has been loaded so far, calling this function will cause an application termination.
+- In case of merge conflicts, between the existing configuration and the add-on configuration, the application will terminate.
+- Add-on configurations are not supposed to have a `global configuration`
+
+</details>
+
+---
+
 ## `mw::com Data Type` API Examples:
 
 ### Example 1: Using `InstanceIdentifier` for Service Instance Management

score/mw/com/impl/BUILD

@@ -1186,6 +1186,8 @@ cc_unit_test(
         "//score/mw/com/impl/configuration:mw_com_config_disabled_trace_config.json",
         "//score/mw/com/impl/configuration:mw_com_config_invalid_trace_config_path.json",
         "//score/mw/com/impl/configuration:mw_com_config_other.json",
+        "//score/mw/com/impl/configuration:mw_com_config_to_merge.json",
+        "//score/mw/com/impl/configuration:mw_com_config_to_merge_second.json",
         "//score/mw/com/impl/configuration:mw_com_config_valid_trace_config.json",
         "//score/mw/com/impl/tracing/configuration:comtrace_filter_config_small.json",
     ],

score/mw/com/impl/configuration/BUILD

@@ -712,6 +712,18 @@ filegroup(
     visibility = ["//score/mw/com:__subpackages__"],
 )
 
+filegroup(
+    name = "mw_com_config_to_merge.json",
+    srcs = ["example/mw_com_config_to_merge.json"],
+    visibility = ["//score/mw/com/impl:__subpackages__"],
+)
+
+filegroup(
+    name = "mw_com_config_to_merge_second.json",
+    srcs = ["example/mw_com_config_to_merge_second.json"],
+    visibility = ["//score/mw/com/impl:__subpackages__"],
+)
+
 filegroup(
     name = "mw_com_config_invalid_trace_config_path.json",
     srcs = ["example/mw_com_config_invalid_trace_config_path.json"],