feat(gateway): Add gateway and transport abstractions

score/mw/com/gateway/BUILD

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+# *******************************************************************************
+# 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
+# *******************************************************************************
+
+package(
+    default_visibility = ["//score/mw/com:__subpackages__"],
+)

score/mw/com/gateway/gateway_application/BUILD

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+# *******************************************************************************
+# 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
+# *******************************************************************************
+
+load("@rules_cc//cc:defs.bzl", "cc_library")
+load("//quality/unit_testing:unit_testing.bzl", "cc_unit_test")
+load("//score/mw:common_features.bzl", "COMPILER_WARNING_FEATURES")
+
+package(
+    default_visibility = ["//score/mw/com/gateway:__subpackages__"],
+)
+
+cc_library(
+    name = "gateway_core",
+    hdrs = ["gateway_core.h"],
+    features = COMPILER_WARNING_FEATURES,
+    visibility = [
+        "//score/mw/com/gateway:__subpackages__",
+    ],
+    deps = [
+        "//score/mw/com/gateway/transport_layer:transport",
+        "//score/mw/com/impl:instance_specifier",
+        "//score/mw/com/impl:service_element_type",
+        "@score_baselibs//score/result",
+    ],
+)
+
+cc_library(
+    name = "gateway_error",
+    srcs = ["gateway_error.cpp"],
+    hdrs = ["gateway_error.h"],
+    features = COMPILER_WARNING_FEATURES,
+    visibility = [
+        "//score/mw/com/gateway:__subpackages__",
+    ],
+    deps = ["@score_baselibs//score/result"],
+)
+
+cc_unit_test(
+    name = "gateway_error_test",
+    srcs = ["gateway_error_test.cpp"],
+    features = COMPILER_WARNING_FEATURES,
+    deps = [
+        ":gateway_error",
+        "@score_baselibs//score/result",
+    ],
+)

score/mw/com/gateway/gateway_application/gateway_core.h

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+/********************************************************************************
+ * 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
+ ********************************************************************************/
+#ifndef SCORE_MW_COM_GATEWAY_GATEWAY_APPLICATION_GATEWAY_CORE_H
+#define SCORE_MW_COM_GATEWAY_GATEWAY_APPLICATION_GATEWAY_CORE_H
+
+#include "score/mw/com/gateway/transport_layer/transport.h"
+#include "score/mw/com/impl/instance_specifier.h"
+#include "score/mw/com/impl/service_element_type.h"
+#include "score/result/result.h"
+
+#include <string>
+#include <vector>
+
+namespace score::mw::com::gateway
+{
+
+class GatewayCore
+{
+  public:
+    virtual ~GatewayCore() = default;
+
+    /// \brief Provide the given service instance locally.
+    /// \details This API is expected to be called by the transport layer implementation, when the transport layer
+    /// receives a request from the remote gateway to provide a service instance. It shall provide/create the given
+    /// service instance locally (e.g. by creating a GenericSkeleton) and offer it.
+    ///
+    /// \param service_instance_specifier instance specifier of the service instance to provide. It is expected, that
+    /// this specifier is configured/existent in the mw_com_config.json at the local gateway side.
+    /// \param service_elements description of the service elements (events, fields, methods) which should be provided
+    /// for the service instance, which will be realized as a GenericSkeleton.
+    /// \return result indicating success or failure.
+    virtual score::Result<void> ProvideService(impl::InstanceSpecifier service_instance_specifier,
+                                               std::vector<ServiceElementConfiguration> service_elements) = 0;
+
+    /// \brief Stop providing the given service instance locally.
+    /// \param service_instance_specifier instance specifier of the service instance to stop offering. It is expected,
+    /// that this specifier is configured/existent in the mw_com_config.json at the local gateway side.
+    virtual void StopOfferService(impl::InstanceSpecifier service_instance_specifier) = 0;
+
+    /// \brief Offer the given service instance locally.
+    /// \param service_instance_specifier instance specifier of the service instance to offer. It is expected, that
+    /// this specifier is configured/existent in the mw_com_config.json at the local gateway side.
+    /// \return result indicating success or failure.
+    virtual score::Result<void> OfferService(impl::InstanceSpecifier service_instance_specifier) = 0;
+
+    /// \brief Register an event-update notification for the given service instance and element locally.
+    /// \param service_instance_specifier instance specifier of the service instance, for which registration takes
+    /// place. It is expected, that this specifier is configured/existent in the mw_com_config.json at the local
+    /// gateway side.
+    /// \param element_type type of the service element (event, field, method). Currently only EVENT is supported.
+    /// \param element_name name of the service element for which update notifications shall be registered.
+    /// \return result indicating success or failure.
+    virtual score::Result<void> RegisterUpdateNotification(impl::InstanceSpecifier service_instance_specifier,
+                                                           impl::ServiceElementType element_type,
+                                                           std::string element_name) = 0;
+
+    /// \brief Unregister an event-update notification for the given service instance and element locally.
+    /// \param service_instance_specifier instance specifier of the service instance, for which unregistration takes
+    /// place. It is expected, that this specifier is configured/existent in the mw_com_config.json at the local
+    /// gateway side.
+    /// \param element_type type of the service element (event, field, method). Currently only EVENT is supported.
+    /// \param element_name name of the service element for which update notifications shall be unregistered.
+    /// \return result indicating success or failure.
+    virtual score::Result<void> UnregisterUpdateNotification(impl::InstanceSpecifier service_instance_specifier,
+                                                             impl::ServiceElementType element_type,
+                                                             std::string element_name) = 0;
+
+    /// \brief Notify an event update for the given service instance and element locally.
+    /// \param service_instance_specifier instance specifier of the service instance, for which notification takes
+    /// place. It is expected, that this specifier is configured/existent in the mw_com_config.json at the local
+    /// gateway side.
+    /// \param updated_element_type type of the element (currently only events supported) for which an update shall be
+    /// notified.
+    /// \param updated_element_name name of the element (e.g. event name) for which an update shall be notified.
+    /// \return result indicating success or failure.
+    virtual score::Result<void> NotifyUpdate(impl::InstanceSpecifier service_instance_specifier,
+                                             impl::ServiceElementType updated_element_type,
+                                             std::string updated_element_name) = 0;
+};
+
+}  // namespace score::mw::com::gateway
+
+#endif  // SCORE_MW_COM_GATEWAY_GATEWAY_APPLICATION_GATEWAY_CORE_H

score/mw/com/gateway/gateway_application/gateway_error.cpp

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+/********************************************************************************
+ * 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/gateway/gateway_application/gateway_error.h"
+
+namespace
+{
+constexpr score::mw::com::gateway::GatewayErrorDomain g_gateway_error_domain;
+}  // namespace
+
+score::result::Error score::mw::com::gateway::MakeError(const GatewayErrorc code, const std::string_view message)
+{
+    return {static_cast<score::result::ErrorCode>(code), g_gateway_error_domain, message};
+}

score/mw/com/gateway/gateway_application/gateway_error.h

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+/********************************************************************************
+ * 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
+ ********************************************************************************/
+#ifndef SCORE_MW_COM_GATEWAY_GATEWAY_APPLICATION_GATEWAY_ERROR_H
+#define SCORE_MW_COM_GATEWAY_GATEWAY_APPLICATION_GATEWAY_ERROR_H
+
+#include "score/result/result.h"
+
+#include <string_view>
+
+namespace score::mw::com::gateway
+{
+
+enum class GatewayErrorc : score::result::ErrorCode
+{
+    kSkeletonCreationFailed = 1,
+    kSkeletonOfferFailed,
+    kSkeletonStopOfferFailed,
+    kUnknownServiceInstance,
+    kUnknownServiceElement,
+    kReceiveHandlerRegistrationFailed,
+    kNonWhitelistedService,
+};
+
+score::result::Error MakeError(const GatewayErrorc code, const std::string_view message = "");
+
+class GatewayErrorDomain final : public score::result::ErrorDomain
+{
+  public:
+    std::string_view MessageFor(const score::result::ErrorCode& code) const noexcept override final
+    {
+        switch (code)
+        {
+            case static_cast<score::result::ErrorCode>(GatewayErrorc::kSkeletonCreationFailed):
+                return "Creation of generic skeleton on destination gateway failed.";
+            case static_cast<score::result::ErrorCode>(GatewayErrorc::kSkeletonOfferFailed):
+                return "Offering of generic skeleton on destination gateway failed.";
+            case static_cast<score::result::ErrorCode>(GatewayErrorc::kUnknownServiceInstance):
+                return "Gateway received an API call for an unknown service instance identifier.";
+            case static_cast<score::result::ErrorCode>(GatewayErrorc::kUnknownServiceElement):
+                return "Gateway received an API call for an unknown service element within an instance identifier.";
+            case static_cast<score::result::ErrorCode>(GatewayErrorc::kReceiveHandlerRegistrationFailed):
+                return "Gateway couldn't register event-receive-handler at its generic proxy to forward event update "
+                       "notifications.";
+            case static_cast<score::result::ErrorCode>(GatewayErrorc::kNonWhitelistedService):
+                return "Gateway received request to provide a non-whitelised service.";
+            default:
+                return "unknown gateway error";
+        }
+    }
+};
+
+}  // namespace score::mw::com::gateway
+
+#endif  // SCORE_MW_COM_GATEWAY_GATEWAY_APPLICATION_GATEWAY_ERROR_H

score/mw/com/gateway/gateway_application/gateway_error_test.cpp

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+/********************************************************************************
+ * 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/gateway/gateway_application/gateway_error.h"
+
+#include <gtest/gtest.h>
+
+namespace score::mw::com::gateway
+{
+namespace
+{
+
+class GatewayErrorTest : public ::testing::Test
+{
+  protected:
+    void TestErrorMessage(const GatewayErrorc error_code, const std::string_view expected_error_output)
+    {
+        const auto error_code_test =
+            gateway_error_domain_dummy_.MessageFor(static_cast<score::result::ErrorCode>(error_code));
+        ASSERT_EQ(error_code_test, expected_error_output);
+    }
+
+    GatewayErrorDomain gateway_error_domain_dummy_{};
+};
+
+TEST_F(GatewayErrorTest, MessageForSkeletonCreationFailed)
+{
+    TestErrorMessage(GatewayErrorc::kSkeletonCreationFailed,
+                     "Creation of generic skeleton on destination gateway failed.");
+}
+
+TEST_F(GatewayErrorTest, MessageForSkeletonOfferFailed)
+{
+    TestErrorMessage(GatewayErrorc::kSkeletonOfferFailed,
+                     "Offering of generic skeleton on destination gateway failed.");
+}
+
+TEST_F(GatewayErrorTest, MessageForSkeletonStopOfferFailedFallsBackToDefault)
+{
+    TestErrorMessage(GatewayErrorc::kSkeletonStopOfferFailed, "unknown gateway error");
+}
+
+TEST_F(GatewayErrorTest, MessageForUnknownServiceInstance)
+{
+    TestErrorMessage(GatewayErrorc::kUnknownServiceInstance,
+                     "Gateway received an API call for an unknown service instance identifier.");
+}
+
+TEST_F(GatewayErrorTest, MessageForUnknownServiceElement)
+{
+    TestErrorMessage(GatewayErrorc::kUnknownServiceElement,
+                     "Gateway received an API call for an unknown service element within an instance identifier.");
+}
+
+TEST_F(GatewayErrorTest, MessageForReceiveHandlerRegistrationFailed)
+{
+    TestErrorMessage(
+        GatewayErrorc::kReceiveHandlerRegistrationFailed,
+        "Gateway couldn't register event-receive-handler at its generic proxy to forward event update notifications.");
+}
+
+TEST_F(GatewayErrorTest, MessageForNonWhitelistedService)
+{
+    TestErrorMessage(GatewayErrorc::kNonWhitelistedService,
+                     "Gateway received request to provide a non-whitelised service.");
+}
+
+TEST_F(GatewayErrorTest, MessageForDefault)
+{
+    TestErrorMessage(static_cast<GatewayErrorc>(-1), "unknown gateway error");
+}
+
+TEST(GatewayError, MakeErrorExpectedError)
+{
+    const score::result::Error err{MakeError(GatewayErrorc::kUnknownServiceInstance)};
+    EXPECT_EQ(*err, static_cast<int>(GatewayErrorc::kUnknownServiceInstance));
+    EXPECT_TRUE(err.UserMessage().empty());
+}
+
+TEST(GatewayError, MakeErrorExpectedErrorWithUserMessage)
+{
+    constexpr std::string_view kUserMessage{"test user message"};
+    const score::result::Error err{MakeError(GatewayErrorc::kSkeletonOfferFailed, kUserMessage)};
+    EXPECT_EQ(*err, static_cast<int>(GatewayErrorc::kSkeletonOfferFailed));
+    EXPECT_EQ(err.UserMessage(), kUserMessage);
+}
+
+}  // namespace
+}  // namespace score::mw::com::gateway