GenericSkeleton supports ReceiveHandler registration notification

score/mw/com/design/skeleton_proxy/generic_skeleton/generic_skeleton_model.puml

@@ -111,19 +111,24 @@ class "mw::com::impl::GenericSkeletonEvent" #yellow {
   +Send(SampleAllocateePtr<void> sample): Result<void>
   +Allocate(): Result<SampleAllocateePtr<void>>
   +GetSizeInfo() const : DataTypeMetaInfo
+  +SetReceiveHandlerRegistrationChangedHandler(score::cpp::callback<void(bool)> callback): Result<void>
+  +UnsetReceiveHandlerRegistrationChangedHandler(): Result<void>
 }
 
 abstract class "GenericSkeletonEventBinding" #yellow {
   +{abstract} Send(SampleAllocateePtr<void> sample) = 0: Result<void>
   +{abstract} Allocate() = 0: Result<SampleAllocateePtr<void>>
   +{abstract} GetSizeInfo() const = 0: std::pair<size_t, size_t>
+  +{abstract} SetReceiveHandlerRegistrationChangedHandler(score::cpp::callback<void(bool)> callback) = 0: Result<void>
+  +{abstract} UnsetReceiveHandlerRegistrationChangedHandler() = 0: Result<void>
 }
 
 class "lola::SkeletonEventCommon" #yellow {
   -parent_: lola::Skeleton&
   -element_fq_id_: ElementFqId
   -control_: score::cpp::optional<EventDataControlComposite>&
   -current_timestamp_: EventSlotStatus::EventTimeStamp&
+  -receive_handler_registration_changed_callback_: std::optional<lola::IMessagePassingService::HandlerStatusChangeCallback>
   +SkeletonEventCommon(lola::Skeleton&, const ElementFqId&, score::cpp::optional<EventDataControlComposite>&, EventSlotStatus::EventTimeStamp&, impl::tracing::SkeletonEventTracingData)
   +PrepareOfferCommon(): void
   +PrepareStopOfferCommon(): void
@@ -132,6 +137,8 @@ class "lola::SkeletonEventCommon" #yellow {
   +IsQmNotificationsRegistered(): bool
   +IsAsilBNotificationsRegistered(): bool
   +GetTracingData(): impl::tracing::SkeletonEventTracingData&
+  +SetReceiveHandlerRegistrationChangedHandler(score::cpp::callback<void(bool)>): Result<void>
+  +UnsetReceiveHandlerRegistrationChangedHandler(): Result<void>
 }
 
 class "lola::GenericSkeletonEvent" #yellow {
@@ -144,6 +151,8 @@ class "lola::GenericSkeletonEvent" #yellow {
   +GetBindingType(): BindingType
   +SetSkeletonEventTracingData(impl::tracing::SkeletonEventTracingData tracing_data): void
   +GetMaxSize() const : std::size_t
+  +SetReceiveHandlerNotificationCallback(score::cpp::callback<void(bool)>): Result<void>
+  +UnsetReceiveHandlerRegistrationChangedHandler(): Result<void>
   -skeleton_event_common_ : lola::SkeletonEventCommon
 }
 

score/mw/com/impl/BUILD

@@ -211,6 +211,7 @@ cc_library(
         "//score/mw/com/impl/plumbing:__pkg__",
     ],
     deps = [
+        ":receive_handler_registration_changed_handler",
         ":skeleton_event_binding",
         "@score_baselibs//score/result",
     ],
@@ -835,6 +836,18 @@ cc_library(
     deps = ["@score_baselibs//score/language/futurecpp"],
 )
 
+cc_library(
+    name = "receive_handler_registration_changed_handler",
+    srcs = ["receive_handler_registration_changed_handler.cpp"],
+    hdrs = ["receive_handler_registration_changed_handler.h"],
+    features = COMPILER_WARNING_FEATURES,
+    tags = ["FFI"],
+    visibility = [
+        "//score/mw/com:__subpackages__",
+    ],
+    deps = ["@score_baselibs//score/language/futurecpp"],
+)
+
 cc_library(
     name = "subscription_state_change_handler",
     srcs = ["subscription_state_change_handler.cpp"],

score/mw/com/impl/bindings/lola/BUILD

@@ -1104,6 +1104,16 @@ cc_unit_test(
     ],
 )
 
+cc_unit_test(
+    name = "skeleton_event_common_test",
+    srcs = ["skeleton_event_common_test.cpp"],
+    features = COMPILER_WARNING_FEATURES,
+    deps = [
+        ":skeleton",
+        "//score/mw/com/impl/bindings/lola/test:skeleton_event_test_resources",
+    ],
+)
+
 cc_unit_test(
     name = "proxy_test",
     srcs = ["proxy_test.cpp"],

score/mw/com/impl/bindings/lola/generic_skeleton_event.h

@@ -59,6 +59,21 @@ class GenericSkeletonEvent : public GenericSkeletonEventBinding
         return size_info_.size;
     }
 
+    /// \brief Set callback, to get notified, when either the 1st event-notification has been registered or the last
+    /// event-notification has been unregistered.
+    /// \detail This extension has been added to GenericSkeletonEvent, because we are only using it so far in the LoLa
+    /// gateway use case.
+    Result<void> SetReceiveHandlerRegistrationChangedHandler(
+        ReceiveHandlerRegistrationChangedCallback callback) noexcept override
+    {
+        return skeleton_event_common_.SetReceiveHandlerRegistrationChangedHandler(std::move(callback));
+    }
+
+    Result<void> UnsetReceiveHandlerRegistrationChangedHandler() noexcept override
+    {
+        return skeleton_event_common_.UnsetReceiveHandlerRegistrationChangedHandler();
+    }
+
   private:
     DataTypeMetaInfo size_info_;
     std::uint8_t* event_data_storage_;

score/mw/com/impl/bindings/lola/skeleton_event_common.h

@@ -24,6 +24,7 @@
 #include "score/mw/com/impl/bindings/lola/transaction_log_registration_guard.h"
 #include "score/mw/com/impl/bindings/lola/type_erased_sample_ptrs_guard.h"
 #include "score/mw/com/impl/configuration/quality_type.h"
+#include "score/mw/com/impl/generic_skeleton_event_binding.h"
 #include "score/mw/com/impl/plumbing/sample_allocatee_ptr.h"
 #include "score/mw/com/impl/runtime.h"
 #include "score/mw/com/impl/skeleton_event_binding.h"
@@ -56,6 +57,8 @@ class SkeletonEventCommon
     // private members and used for testing purposes only.
     friend class SkeletonEventAttorney<SampleType>;
 
+    using ReceiveHandlerRegistrationChangedCallback = lola::IMessagePassingService::HandlerStatusChangeCallback;
+
   public:
     SkeletonEventCommon(Skeleton& parent,
                         const std::string_view event_name,
@@ -109,6 +112,25 @@ class SkeletonEventCommon
         return consumer_control_local_view_qm_.value();
     }
 
+    /// \brief Set callback, to get notified, when either the 1st event-notification has been registered or the last
+    /// event-notification has been unregistered.
+    /// \detail This extension has been added to GenericSkeletonEvent, because we are only using it so far in the LoLa
+    /// gateway use case.
+    Result<void> SetReceiveHandlerRegistrationChangedHandler(
+        ReceiveHandlerRegistrationChangedCallback callback) noexcept
+    {
+        static_assert(std::is_same_v<decltype(callback), ReceiveHandlerRegistrationChangedCallback>,
+                      "Callback type mismatch between GenericSkeletonEvent and lola::GenericSkeletonEvent");
+        receive_handler_registration_changed_callback_ = std::move(callback);
+        return {};
+    }
+
+    Result<void> UnsetReceiveHandlerRegistrationChangedHandler()
+    {
+        receive_handler_registration_changed_callback_.reset();
+        return {};
+    }
+
   private:
     Skeleton& parent_;
     std::string_view event_name_;
@@ -142,6 +164,8 @@ class SkeletonEventCommon
     /// PrepareStopOfferCommon().
     std::optional<TransactionLogRegistrationGuard> transaction_log_registration_guard_{};
     std::optional<tracing::TypeErasedSamplePtrsGuard> type_erased_sample_ptrs_guard_{};
+    // ReceiveHandlerRegistrationChangedCallback
+    std::optional<ReceiveHandlerRegistrationChangedCallback> receive_handler_registration_changed_callback_;
 
     void EmplaceTransactionLogRegistrationGuard(TransactionLogSet& transaction_log_set);
     void EmplaceTypeErasedSamplePtrsGuard();
@@ -214,6 +238,11 @@ void SkeletonEventCommon<SampleType>::PrepareOfferCommon(EventControl& event_con
         .RegisterEventNotificationExistenceChangedCallback(
             QualityType::kASIL_QM, element_fq_id_, [this](const bool has_handlers) noexcept {
                 SetQmNotificationsRegistered(has_handlers);
+                if (receive_handler_registration_changed_callback_.has_value())
+                {
+                    const bool qm_registered = qm_event_update_notifications_registered_.load();
+                    receive_handler_registration_changed_callback_.value()(qm_registered);
+                }
             });
 
     if (parent_.GetInstanceQualityType() == QualityType::kASIL_B)
@@ -223,6 +252,11 @@ void SkeletonEventCommon<SampleType>::PrepareOfferCommon(EventControl& event_con
             .RegisterEventNotificationExistenceChangedCallback(
                 QualityType::kASIL_B, element_fq_id_, [this](const bool has_handlers) noexcept {
                     SetAsilBNotificationsRegistered(has_handlers);
+                    if (receive_handler_registration_changed_callback_.has_value())
+                    {
+                        const bool asil_b_registered = asil_b_event_update_notifications_registered_.load();
+                        receive_handler_registration_changed_callback_.value()(asil_b_registered);
+                    }
                 });
     }
 }

score/mw/com/impl/bindings/lola/skeleton_event_common_test.cpp

@@ -0,0 +1,157 @@
+/********************************************************************************
+ * Copyright (c) 2026 Contributors to the Eclipse Foundation
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information regarding copyright ownership.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Apache License Version 2.0 which is available at
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ ********************************************************************************/
+
+#include "score/mw/com/impl/bindings/lola/skeleton_event_common.h"
+#include "score/mw/com/impl/bindings/lola/test/skeleton_event_test_resources.h"
+
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+namespace score::mw::com::impl::lola
+{
+namespace
+{
+
+using ::testing::_;
+using ::testing::AnyNumber;
+using ::testing::Return;
+using ::testing::ReturnRef;
+
+class SkeletonEventCommonFixture : public SkeletonEventFixture
+{
+  public:
+    SkeletonEventCommonFixture()
+    {
+        ON_CALL(runtime_mock_, GetServiceDiscovery()).WillByDefault(ReturnRef(service_discovery_mock_));
+    }
+
+    void InitialiseSkeletonEventCommon(const ElementFqId element_fq_id,
+                                       const std::string& service_element_name,
+                                       const std::size_t max_samples,
+                                       const std::uint8_t max_subscribers,
+                                       const bool enforce_max_samples,
+                                       const QualityType quality_type,
+                                       impl::tracing::SkeletonEventTracingData skeleton_event_tracing_data)
+    {
+        // We defer initialisation of the Skeleton to InitialiseSkeletonEventCommon to allow test fixtures to set any
+        // mocked expectations before creating the skeleton.
+        InitialiseSkeleton(GetValidInstanceIdentifierForEventCommon(quality_type));
+
+        SkeletonBinding::SkeletonEventBindings events{};
+        SkeletonBinding::SkeletonFieldBindings fields{};
+        std::optional<SkeletonBinding::RegisterShmObjectTraceCallback> register_shm_object_trace_callback{};
+
+        std::ignore = skeleton_->PrepareOffer(events, fields, std::move(register_shm_object_trace_callback));
+
+        skeleton_event_ = std::make_unique<SkeletonEvent<test::TestSampleType>>(
+            *skeleton_,
+            element_fq_id,
+            service_element_name,
+            SkeletonEventProperties{max_samples, max_subscribers, enforce_max_samples},
+            skeleton_event_tracing_data);
+
+        // Call PrepareOffer on the skeleton event to trigger Skeleton::Register, which populates
+        // the event_controls_ maps in ServiceDataControl for both QM and (if ASIL-B) ASIL-B.
+        std::ignore = skeleton_event_->PrepareOffer();
+
+        skeleton_event_common_ =
+            std::make_unique<score::mw::com::impl::lola::SkeletonEventCommon<test::TestSampleType>>(
+                *skeleton_,
+                event_name_,
+                SkeletonEventProperties{max_samples, max_subscribers, enforce_max_samples},
+                element_fq_id,
+                skeleton_event_tracing_data);
+    }
+
+  protected:
+    std::string_view event_name_{"test_event"};
+    std::unique_ptr<SkeletonEventCommon<test::TestSampleType>> skeleton_event_common_;
+
+    InstanceIdentifier GetValidInstanceIdentifierForEventCommon(QualityType quality_type) const
+    {
+        if (quality_type == QualityType::kASIL_B)
+        {
+            return make_InstanceIdentifier(valid_asil_instance_deployment_, valid_type_deployment_);
+        }
+        else
+        {
+            return make_InstanceIdentifier(valid_qm_instance_deployment_, valid_type_deployment_);
+        }
+    }
+
+  private:
+    ServiceInstanceDeployment valid_qm_instance_deployment_{make_ServiceIdentifierType(service_type_name_),
+                                                            binding_info_,
+                                                            QualityType::kASIL_QM,
+                                                            instance_specifier_};
+};
+
+TEST_F(SkeletonEventCommonFixture, RegisterEventNotificationCallbacksForAsilBTriggersMessagePassingRegistration)
+{
+    const bool enforce_max_samples{true};
+    InitialiseSkeletonEventCommon(fake_element_fq_id_,
+                                  fake_event_name_,
+                                  max_samples_,
+                                  max_subscribers_,
+                                  enforce_max_samples,
+                                  QualityType::kASIL_B,
+                                  {});
+
+    auto* const event_control_qm = GetEventControl(fake_element_fq_id_, QualityType::kASIL_QM);
+    auto* const event_control_asil_b = GetEventControl(fake_element_fq_id_, QualityType::kASIL_B);
+    ASSERT_NE(event_control_qm, nullptr);
+    ASSERT_NE(event_control_asil_b, nullptr);
+
+    // Expect that RegisterEventNotificationExistenceChangedCallback is called once per quality type with correct ASIL
+    // level and element ID
+    EXPECT_CALL(message_passing_mock_,
+                RegisterEventNotificationExistenceChangedCallback(impl::QualityType::kASIL_B, fake_element_fq_id_, _))
+        .Times(1);
+    EXPECT_CALL(message_passing_mock_,
+                RegisterEventNotificationExistenceChangedCallback(impl::QualityType::kASIL_QM, fake_element_fq_id_, _))
+        .Times(1);
+    // ... when PrepareOfferCommon is called
+    skeleton_event_common_->PrepareOfferCommon(*event_control_qm, event_control_asil_b);
+}
+
+TEST_F(SkeletonEventCommonFixture, UnregisterEventNotificationCallbacksForAsilBTriggersMessagePassingUnregistration)
+{
+    const bool enforce_max_samples{true};
+    InitialiseSkeletonEventCommon(fake_element_fq_id_,
+                                  fake_event_name_,
+                                  max_samples_,
+                                  max_subscribers_,
+                                  enforce_max_samples,
+                                  QualityType::kASIL_B,
+                                  {});
+
+    auto* const event_control_qm = GetEventControl(fake_element_fq_id_, QualityType::kASIL_QM);
+    auto* const event_control_asil_b = GetEventControl(fake_element_fq_id_, QualityType::kASIL_B);
+    ASSERT_NE(event_control_qm, nullptr);
+    ASSERT_NE(event_control_asil_b, nullptr);
+
+    // Expect that RegisterEventNotificationExistenceChangedCallback is called once per quality type with correct ASIL
+    // level and element ID
+    EXPECT_CALL(message_passing_mock_,
+                UnregisterEventNotificationExistenceChangedCallback(impl::QualityType::kASIL_B, fake_element_fq_id_))
+        .Times(1);
+    EXPECT_CALL(message_passing_mock_,
+                UnregisterEventNotificationExistenceChangedCallback(impl::QualityType::kASIL_QM, fake_element_fq_id_))
+        .Times(1);
+    // ... when PrepareStopOfferCommon is called
+    skeleton_event_common_->PrepareStopOfferCommon();
+}
+
+}  // namespace
+
+}  // namespace score::mw::com::impl::lola

score/mw/com/impl/bindings/mock_binding/generic_skeleton_event.h

@@ -37,6 +37,11 @@ class GenericSkeletonEvent : public GenericSkeletonEventBinding
     MOCK_METHOD(BindingType, GetBindingType, (), (const, noexcept, override));
     MOCK_METHOD(void, SetSkeletonEventTracingData, (impl::tracing::SkeletonEventTracingData), (noexcept, override));
     MOCK_METHOD(std::size_t, GetMaxSize, (), (const, noexcept, override));
+    MOCK_METHOD(Result<void>,
+                SetReceiveHandlerRegistrationChangedHandler,
+                (ReceiveHandlerRegistrationChangedCallback),
+                (noexcept, override));
+    MOCK_METHOD(Result<void>, UnsetReceiveHandlerRegistrationChangedHandler, (), (noexcept, override));
 };
 
 }  // namespace score::mw::com::impl::mock_binding

score/mw/com/impl/generic_skeleton_event.cpp

@@ -97,4 +97,26 @@ DataTypeMetaInfo GenericSkeletonEvent::GetSizeInfo() const noexcept
     return {size_info_pair.first, size_info_pair.second};
 }
 
+Result<void> GenericSkeletonEvent::SetReceiveHandlerRegistrationChangedHandler(
+    ReceiveHandlerRegistrationChangedCallback callback) noexcept
+{
+    auto* const binding = dynamic_cast<GenericSkeletonEventBinding*>(binding_.get());
+    SCORE_LANGUAGE_FUTURECPP_ASSERT_PRD_MESSAGE(
+        binding != nullptr,
+        "Cast to GenericSkeletonEventBinding failed, but ReceiveHandlerNotification is only supported for "
+        "GenericSkeletonEvents.");
+
+    return binding->SetReceiveHandlerRegistrationChangedHandler(std::move(callback));
+}
+
+Result<void> GenericSkeletonEvent::UnsetReceiveHandlerRegistrationChangedHandler() noexcept
+{
+    auto* const binding = dynamic_cast<GenericSkeletonEventBinding*>(binding_.get());
+    SCORE_LANGUAGE_FUTURECPP_ASSERT_PRD_MESSAGE(
+        binding != nullptr,
+        "Cast to GenericSkeletonEventBinding failed, but ReceiveHandlerNotification is only supported for "
+        "GenericSkeletonEvents.");
+
+    return binding->UnsetReceiveHandlerRegistrationChangedHandler();
+}
 }  // namespace score::mw::com::impl