SPEC-1924: AGL Speech Framework's Voice Service High Level 1.0 Release.

Details:
1) Control plugin implementation for VSHL 1.0
2) Exposed APIs that are documented in the confluence page
   https://confluence.automotivelinux.org/display/SPE/Speech+EG+Architecture
3) Implemented 39 unit tests based on GTest framework to test all the low
level components of VSHL binding.
4) Implemented a HTML5 based VSHL API tester application to test VSHL APIs.

API specification:
https://confluence.automotivelinux.org/display/SPE/Speech+EG+Architecture#SpeechEGArchitecture-HighLevelVoiceService

Test performed:
1) Tested AGL service running Alexa Auto SDK https://github.com/alexa/aac-sdk on Ubuntu 16.04 and Renesas R-Car M3 board.

License:
Apache 2.0

Developers/Owners:
Naveen Bobbili (nbobbili@amazon.com)
Prakash Buddhiraja (buddhip@amazon.com)
Shotaro Uchida (shotaru@amazon.co.jp)

Change-Id: I3370f4ad65aff030f24f4ad571fb02d525bbfbca
Signed-off-by: Naveen Bobbili  <nbobbili@amazon.com>

22 files changed, 1785 insertions, 0 deletions

diff --git a/src/plugins/capabilities/CapabilitiesFactory.cpp b/src/plugins/capabilities/CapabilitiesFactory.cpp
new file mode 100644
index 0000000..2f92519
--- /dev/null
+++ b/src/plugins/capabilities/CapabilitiesFactory.cpp
@@ -0,0 +1,57 @@
+/*
+ * Copyright 2018-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *     http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+
+#include "capabilities/CapabilitiesFactory.h"
+
+#include "capabilities/communication/include/PhoneControlCapability.h"
+#include "capabilities/guimetadata/include/GuiMetadataCapability.h"
+#include "capabilities/navigation/include/NavigationCapability.h"
+
+static string TAG = "vshl::core::CapabilitiesFactory";
+
+using Level = vshl::utilities::logging::Logger::Level;
+
+namespace vshl {
+namespace capabilities {
+
+// Create CapabilitiesFactory
+std::unique_ptr<CapabilitiesFactory> CapabilitiesFactory::create() {
+    auto capabilitiesFactory = std::unique_ptr<CapabilitiesFactory>(new CapabilitiesFactory());
+    return capabilitiesFactory;
+}
+
+std::shared_ptr<common::interfaces::ICapability> CapabilitiesFactory::getGuiMetadata() {
+    if (!mGuiMetadata) {
+        mGuiMetadata = vshl::capabilities::guimetadata::GuiMetadata::create();
+    }
+    return mGuiMetadata;
+}
+
+std::shared_ptr<common::interfaces::ICapability> CapabilitiesFactory::getPhoneControl() {
+    if (!mPhoneControl) {
+        mPhoneControl = vshl::capabilities::phonecontrol::PhoneControl::create();
+    }
+    return mPhoneControl;
+}
+
+std::shared_ptr<common::interfaces::ICapability> CapabilitiesFactory::getNavigation() {
+    if (!mNavigation) {
+        mNavigation = vshl::capabilities::navigation::Navigation::create();
+    }
+    return mNavigation;
+}
+
+}  // namespace capabilities
+}  // namespace vshl
\ No newline at end of file
diff --git a/src/plugins/capabilities/CapabilitiesFactory.h b/src/plugins/capabilities/CapabilitiesFactory.h
new file mode 100644
index 0000000..b73909b
--- /dev/null
+++ b/src/plugins/capabilities/CapabilitiesFactory.h
@@ -0,0 +1,63 @@
+/*
+ * Copyright 2018-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *     http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+#ifndef VSHL_CAPABILITIES_CAPABILITIESFACTORY_H_
+#define VSHL_CAPABILITIES_CAPABILITIESFACTORY_H_
+
+#include <memory>
+
+#include "interfaces/capabilities/ICapability.h"
+#include "utilities/logging/Logger.h"
+
+using namespace std;
+
+namespace vshl {
+namespace capabilities {
+/*
+ * Factory for creating different capability objects.
+ */
+class CapabilitiesFactory {
+public:
+    // Create CapabilitiesFactory
+    static std::unique_ptr<CapabilitiesFactory> create();
+
+    // GUI Metadata capability
+    std::shared_ptr<common::interfaces::ICapability> getGuiMetadata();
+
+    // Phone call control capability
+    std::shared_ptr<common::interfaces::ICapability> getPhoneControl();
+
+    // Navigation capability
+    std::shared_ptr<common::interfaces::ICapability> getNavigation();
+
+    // Destructor
+    ~CapabilitiesFactory() = default;
+
+private:
+    // Constructor
+    CapabilitiesFactory() = default;
+
+    // Capabilities
+    shared_ptr<vshl::common::interfaces::ICapability> mGuiMetadata;
+    shared_ptr<vshl::common::interfaces::ICapability> mPhoneControl;
+    shared_ptr<vshl::common::interfaces::ICapability> mNavigation;
+
+    // Logger
+    unique_ptr<vshl::utilities::logging::Logger> mLogger;
+};
+
+}  // namespace capabilities
+}  // namespace vshl
+
+#endif  // VSHL_CAPABILITIES_CAPABILITIESFACTORY_H_
diff --git a/src/plugins/capabilities/CapabilityMessagingService.cpp b/src/plugins/capabilities/CapabilityMessagingService.cpp
new file mode 100644
index 0000000..91b5f2b
--- /dev/null
+++ b/src/plugins/capabilities/CapabilityMessagingService.cpp
@@ -0,0 +1,117 @@
+/*
+ * Copyright 2018-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *     http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+#include "capabilities/CapabilityMessagingService.h"
+
+#include "capabilities/core/include/PublisherForwarder.h"
+#include "capabilities/core/include/SubscriberForwarder.h"
+
+static string TAG = "vshl::capabilities::CapabilityMessagingService";
+
+using Level = vshl::common::interfaces::ILogger::Level;
+
+namespace vshl {
+namespace capabilities {
+
+// Create a CapabilityMessagingService.
+unique_ptr<CapabilityMessagingService> CapabilityMessagingService::create(
+    shared_ptr<vshl::common::interfaces::ILogger> logger,
+    shared_ptr<vshl::common::interfaces::IAFBApi> afbApi) {
+    if (logger == nullptr) {
+        return nullptr;
+    }
+
+    if (afbApi == nullptr) {
+        logger->log(Level::ERROR, TAG, "Failed to create CapabilityMessagingService: AFB API null");
+        return nullptr;
+    }
+
+    auto capabilityMessageService =
+        std::unique_ptr<CapabilityMessagingService>(new CapabilityMessagingService(logger, afbApi));
+    return capabilityMessageService;
+}
+
+CapabilityMessagingService::~CapabilityMessagingService() {
+    mMessageChannelsMap.clear();
+}
+
+CapabilityMessagingService::CapabilityMessagingService(
+    shared_ptr<vshl::common::interfaces::ILogger> logger,
+    shared_ptr<vshl::common::interfaces::IAFBApi> afbApi) :
+        mAfbApi(afbApi),
+        mLogger(logger) {
+}
+
+// Subscribe to capability specific messages.
+bool CapabilityMessagingService::subscribe(
+    vshl::common::interfaces::IAFBRequest& request,
+    shared_ptr<common::interfaces::ICapability> capability,
+    const string action) {
+    auto capabilityName = capability->getName();
+
+    if (capabilityName.empty()) {
+        mLogger->log(Level::ERROR, TAG, "Failed to subscribe to message. Invalid input.");
+        return false;
+    }
+
+    auto messageChannel = getMessageChannel(capability);
+    return messageChannel->subscribe(request, action);
+}
+
+// Publish capability messages.
+bool CapabilityMessagingService::publish(
+    shared_ptr<common::interfaces::ICapability> capability,
+    const string action,
+    const string payload) {
+    auto capabilityName = capability->getName();
+
+    if (capabilityName.empty()) {
+        mLogger->log(Level::ERROR, TAG, "Failed to publish message. Invalid input.");
+        return false;
+    }
+
+    auto messageChannelIt = mMessageChannelsMap.find(capabilityName);
+    if (messageChannelIt == mMessageChannelsMap.end()) {
+        mLogger->log(
+            Level::ERROR,
+            TAG,
+            "Failed to publish message. Message channel doesn't exist for capability " + capabilityName);
+        return false;
+    }
+
+    return messageChannelIt->second->publish(action, payload);
+}
+
+shared_ptr<vshl::capabilities::core::MessageChannel> CapabilityMessagingService::getMessageChannel(
+    shared_ptr<common::interfaces::ICapability> capability) {
+    auto capabilityName = capability->getName();
+
+    if (capabilityName.empty()) {
+        mLogger->log(Level::ERROR, TAG, "Failed to create message channel. Invalid input.");
+        return nullptr;
+    }
+
+    auto messageChannelIt = mMessageChannelsMap.find(capabilityName);
+    if (messageChannelIt == mMessageChannelsMap.end()) {
+        mLogger->log(Level::INFO, TAG, "Creating new message channel for capability: " + capabilityName);
+        auto messageChannel = vshl::capabilities::core::MessageChannel::create(mLogger, mAfbApi, capability);
+        mMessageChannelsMap.insert(make_pair(capabilityName, messageChannel));
+        return messageChannel;
+    }
+
+    return messageChannelIt->second;
+}
+
+}  // namespace capabilities
+}  // namespace vshl
diff --git a/src/plugins/capabilities/CapabilityMessagingService.h b/src/plugins/capabilities/CapabilityMessagingService.h
new file mode 100644
index 0000000..535e806
--- /dev/null
+++ b/src/plugins/capabilities/CapabilityMessagingService.h
@@ -0,0 +1,82 @@
+/*
+ * Copyright 2018-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *     http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+#ifndef VSHL_CAPABILITIES_CAPABILITYMESSAGINGSERVICE_H_
+#define VSHL_CAPABILITIES_CAPABILITYMESSAGINGSERVICE_H_
+
+#include <memory>
+#include <string>
+#include <unordered_map>
+
+#include "capabilities/core/include/MessageChannel.h"
+#include "interfaces/afb/IAFBApi.h"
+#include "interfaces/capabilities/ICapability.h"
+#include "interfaces/utilities/logging/ILogger.h"
+
+using namespace std;
+
+namespace vshl {
+namespace capabilities {
+/*
+ * This hosts service APIs that clients can use to subscribe and
+ * forward capability messages. Each capability has a name and
+ * direction (upstream/downstream). Upstream messages are from
+ * voiceagents to Apps and downstream messages are Apps to voiceagents.
+ * This class will use a factory to create publisher and subcribers for
+ * each capability and create assiociations between them.
+ */
+class CapabilityMessagingService {
+public:
+  // Create a CapabilityMessagingService.
+  static std::unique_ptr<CapabilityMessagingService>
+  create(shared_ptr<vshl::common::interfaces::ILogger> logger,
+         shared_ptr<vshl::common::interfaces::IAFBApi> afbApi);
+
+  // Subscribe to capability specific messages.
+  bool subscribe(vshl::common::interfaces::IAFBRequest &request,
+                 shared_ptr<common::interfaces::ICapability> capability,
+                 const string action);
+
+  // Publish capability messages.
+  bool publish(shared_ptr<common::interfaces::ICapability> capability,
+               const string action, const string payload);
+
+  // Destructor
+  ~CapabilityMessagingService();
+
+private:
+  // Constructor
+  CapabilityMessagingService(
+      shared_ptr<vshl::common::interfaces::ILogger> logger,
+      shared_ptr<vshl::common::interfaces::IAFBApi> afbApi);
+
+  // Binding API reference
+  shared_ptr<vshl::common::interfaces::IAFBApi> mAfbApi;
+
+  // Create a message channel for the capability.
+  shared_ptr<vshl::capabilities::core::MessageChannel>
+  getMessageChannel(shared_ptr<common::interfaces::ICapability> capability);
+
+  // Map of capabilities to message channels.
+  unordered_map<string, shared_ptr<vshl::capabilities::core::MessageChannel>>
+      mMessageChannelsMap;
+
+  // Logger
+  shared_ptr<vshl::common::interfaces::ILogger> mLogger;
+};
+
+} // namespace capabilities
+} // namespace vshl
+
+#endif // VSHL_CAPABILITIES_CAPABILITYMESSAGINGSERVICE_H_
diff --git a/src/plugins/capabilities/communication/include/PhoneControlCapability.h b/src/plugins/capabilities/communication/include/PhoneControlCapability.h
new file mode 100644
index 0000000..55ada8d
--- /dev/null
+++ b/src/plugins/capabilities/communication/include/PhoneControlCapability.h
@@ -0,0 +1,52 @@
+/*
+ * Copyright 2018-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *     http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+
+#ifndef VSHL_CAPABILITIES_PHONECONTROL_CAPABILITY_H_
+#define VSHL_CAPABILITIES_PHONECONTROL_CAPABILITY_H_
+
+#include <memory>
+
+#include "interfaces/capabilities/ICapability.h"
+
+namespace vshl {
+namespace capabilities {
+namespace phonecontrol {
+
+/*
+ * PhoneControl capability. Calls are initiated in the endpoint.
+ */
+class PhoneControl : public common::interfaces::ICapability {
+public:
+    // Create a PhoneControl.
+    static std::shared_ptr<PhoneControl> create();
+
+    ~PhoneControl() = default;
+
+protected:
+    string getName() const override;
+
+    list<string> getUpstreamMessages() const override;
+
+    list<string> getDownstreamMessages() const override;
+
+private:
+    PhoneControl() = default;
+};
+
+}  // namespace phonecontrol
+}  // namespace capabilities
+}  // namespace vshl
+
+#endif  // VSHL_CAPABILITIES_PHONECONTROL_CAPABILITY_H_
diff --git a/src/plugins/capabilities/communication/include/PhoneControlMessages.h b/src/plugins/capabilities/communication/include/PhoneControlMessages.h
new file mode 100644
index 0000000..4c68455
--- /dev/null
+++ b/src/plugins/capabilities/communication/include/PhoneControlMessages.h
@@ -0,0 +1,128 @@
+/*
+ * Copyright 2018-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *     http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+#ifndef VSHL_CAPABILITIES_PHONECONTROL_MESSAGES_H_
+#define VSHL_CAPABILITIES_PHONECONTROL_MESSAGES_H_
+
+#include <list>
+#include <string>
+
+using namespace std;
+
+namespace vshl {
+namespace capabilities {
+namespace phonecontrol {
+
+static string NAME = "phonecontrol";
+
+// Supported actions from VA -> Apps
+/* Dial message sent from VA to app handling the calling.
+ *
+ * Payload
+ *  {
+ *     "callId": "{{STRING}}",
+ *     "callee": {
+ *       "details": "{{STRING}}",
+ *       "defaultAddress": {
+ *         "protocol": "{{STRING}}",
+ *         "format": "{{STRING}}",
+ *         "value": "{{STRING}}"
+ *       },
+ *       "alternativeAddresses": [{
+ *         "protocol": "{{STRING}}",
+ *         "format": "{{STRING}}",
+ *         "value": {{STRING}}
+ *       }]
+ *     }
+ *   }
+ * }
+ *
+ * callId (required): A unique identifier for the call
+ * callee (required): The destination of the outgoing call
+ * callee.details (optional): Descriptive information about the callee
+ * callee.defaultAddress (required): The default address to use for calling the callee
+ * callee.alternativeAddresses (optional): An array of alternate addresses for the existing callee
+ * address.protocol (required): The protocol for this address of the callee (e.g. PSTN, SIP, H323, etc.)
+ * address.format (optional): The format for this address of the callee (e.g. E.164, E.163, E.123, DIN5008, etc.)
+ * address.value (required): The address of the callee.
+ *
+ */
+static string PHONECONTROL_DIAL = "dial";
+
+// Supported actions from Apps -> VA
+/*
+ *  App notifies the voiceagents of a change in connection state of a calling device.
+ *
+ *  Payload
+ *  {
+ *	    "state" : "{{STRING}}" // CONNECTED or DISCONNECTED
+ *  }
+ */
+static string PHONECONTROL_CONNECTIONSTATE_CHANGED = "connection_state_changed";
+/*
+ *  App notifies the voiceagents that call is activated
+ *
+ *  callId must match the one that is sent by VA with DIAL message above.
+ *
+ *  Payload
+ *  {
+ *	    "callId" : "{{STRING}}"
+ *  }
+ */
+static string PHONECONTROL_CALL_ACTIVATED = "call_activated";
+/*
+ *  App notifies the voiceagents of an error in initiating or maintaining a
+ *  call on a calling device
+ *
+ *  callId must match the one that is sent by VA with DIAL message above.
+ *  error: below status codes.
+ *     4xx: Validation failure for the input from the DIAL message
+ *     500: Internal error on the platform unrelated to the cellular network
+ *     503: Error on the platform related to the cellular network
+ *
+ *  Payload
+ *  {
+ *	    "callId" : "{{STRING}}"
+ *      "error"  : "{{STRING}}"
+ *  }
+ */
+static string PHONECONTROL_CALL_FAILED = "call_failed";
+/*
+ *  App notifies the voiceagents that call is terminated
+ *
+ *  callId must match the one that is sent by VA with DIAL message above.
+ *
+ *  Payload
+ *  {
+ *	    "callId" : "{{STRING}}"
+ *  }
+ */
+static string PHONECONTROL_CALL_TERMINATED = "call_terminated";
+
+// List of actions that are delivered from VA -> Apps
+static list<string> PHONECONTROL_UPSTREAM_ACTIONS = {
+    PHONECONTROL_DIAL,
+};
+
+// List of actions that are delivered from Apps -> VA
+static list<string> PHONECONTROL_DOWNSTREAM_ACTIONS = {PHONECONTROL_CONNECTIONSTATE_CHANGED,
+                                                       PHONECONTROL_CALL_ACTIVATED,
+                                                       PHONECONTROL_CALL_FAILED,
+                                                       PHONECONTROL_CALL_TERMINATED};
+
+}  // namespace phonecontrol
+}  // namespace capabilities
+}  // namespace vshl
+
+#endif  // VSHL_CAPABILITIES_PHONECONTROL_MESSAGES_H_
diff --git a/src/plugins/capabilities/communication/src/PhoneControlCapability.cpp b/src/plugins/capabilities/communication/src/PhoneControlCapability.cpp
new file mode 100644
index 0000000..6a74d5a
--- /dev/null
+++ b/src/plugins/capabilities/communication/src/PhoneControlCapability.cpp
@@ -0,0 +1,42 @@
+/*
+ * Copyright 2018-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *     http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+#include "capabilities/communication/include/PhoneControlCapability.h"
+#include "capabilities/communication/include/PhoneControlMessages.h"
+
+namespace vshl {
+namespace capabilities {
+namespace phonecontrol {
+
+// Create a phonecontrol.
+shared_ptr<PhoneControl> PhoneControl::create() {
+    auto phonecontrol = std::shared_ptr<PhoneControl>(new PhoneControl());
+    return phonecontrol;
+}
+
+string PhoneControl::getName() const {
+    return NAME;
+}
+
+list<string> PhoneControl::getUpstreamMessages() const {
+    return PHONECONTROL_UPSTREAM_ACTIONS;
+}
+
+list<string> PhoneControl::getDownstreamMessages() const {
+    return PHONECONTROL_DOWNSTREAM_ACTIONS;
+}
+
+}  // namespace phonecontrol
+}  // namespace capabilities
+}  // namespace vshl
diff --git a/src/plugins/capabilities/core/include/MessageChannel.h b/src/plugins/capabilities/core/include/MessageChannel.h
new file mode 100644
index 0000000..504e241
--- /dev/null
+++ b/src/plugins/capabilities/core/include/MessageChannel.h
@@ -0,0 +1,68 @@
+/*
+ * Copyright 2018-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *     http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+#ifndef VSHL_CAPABILITIES_CORE_MESSAGECHANNEL_H_
+#define VSHL_CAPABILITIES_CORE_MESSAGECHANNEL_H_
+
+#include <memory>
+
+#include "capabilities/core/include/PublisherForwarder.h"
+#include "capabilities/core/include/SubscriberForwarder.h"
+#include "interfaces/afb/IAFBApi.h"
+#include "interfaces/capabilities/ICapability.h"
+#include "interfaces/utilities/logging/ILogger.h"
+
+using namespace std;
+
+namespace vshl {
+namespace capabilities {
+namespace core {
+/*
+ * MessageChannel has one end as publisher forwarder and the other end
+ * as subscriber forwarder.
+ */
+class MessageChannel {
+public:
+  // Create a MessageChannel.
+  static std::shared_ptr<MessageChannel>
+  create(shared_ptr<vshl::common::interfaces::ILogger> logger,
+         shared_ptr<vshl::common::interfaces::IAFBApi> afbApi,
+         shared_ptr<vshl::common::interfaces::ICapability> capability);
+
+  // Sends the message
+  bool publish(const string action, const string payload);
+
+  // Subscribe
+  bool subscribe(vshl::common::interfaces::IAFBRequest &request,
+                 const string action);
+
+  // Destructor
+  virtual ~MessageChannel() = default;
+
+private:
+  // Constructor
+  MessageChannel(shared_ptr<vshl::common::interfaces::ILogger> logger,
+                 shared_ptr<vshl::common::interfaces::IAFBApi> afbApi,
+                 shared_ptr<vshl::common::interfaces::ICapability> capability);
+
+  // Forwarders
+  shared_ptr<PublisherForwarder> mPublisherForwarder;
+  shared_ptr<SubscriberForwarder> mSubscriberForwarder;
+};
+
+} // namespace core
+} // namespace capabilities
+} // namespace vshl
+
+#endif // VSHL_CAPABILITIES_CORE_MESSAGECHANNEL_H_
diff --git a/src/plugins/capabilities/core/include/PublisherForwarder.h b/src/plugins/capabilities/core/include/PublisherForwarder.h
new file mode 100644
index 0000000..9cc89b5
--- /dev/null
+++ b/src/plugins/capabilities/core/include/PublisherForwarder.h
@@ -0,0 +1,73 @@
+/*
+ * Copyright 2018-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *     http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+#ifndef VSHL_CAPABILITIES_CORE_PUBLISHERFORWARDER_H_
+#define VSHL_CAPABILITIES_CORE_PUBLISHERFORWARDER_H_
+
+#include <memory>
+
+#include "capabilities/core/include/SubscriberForwarder.h"
+
+#include "interfaces/afb/IAFBApi.h"
+#include "interfaces/capabilities/ICapability.h"
+#include "interfaces/utilities/logging/ILogger.h"
+
+using namespace std;
+
+namespace vshl {
+namespace capabilities {
+namespace core {
+/*
+ * This class is responsible for forwarding the messages to be published
+ * to subscriber forwarder. Subscriber forwarder will deliver the messages
+ * as AFB Events to all the subscribed clients.
+ * There is one PublisherForwarder and one SubscriberForwarder per capability.
+ */
+class PublisherForwarder {
+public:
+    // Create a PublisherForwarder.
+    static std::shared_ptr<PublisherForwarder> create(
+        shared_ptr<vshl::common::interfaces::ILogger> logger,
+        shared_ptr<vshl::common::interfaces::ICapability> capability);
+
+    // Connect a subscriber forwarder to this publisher forwarder
+    void setSubscriberForwarder(shared_ptr<SubscriberForwarder> subscriberForwarder);
+
+    // Forward message to the subscriber forwarder
+    bool forwardMessage(const string action, const string payload);
+
+    // Destructor
+    ~PublisherForwarder();
+
+private:
+    // Constructor
+    PublisherForwarder(
+        shared_ptr<vshl::common::interfaces::ILogger> logger,
+        shared_ptr<vshl::common::interfaces::ICapability> capability);
+
+    // Subscriber forwarder connected to this publisher forwarder.
+    shared_ptr<SubscriberForwarder> mSubscriberForwarder;
+
+    // Capability
+    shared_ptr<vshl::common::interfaces::ICapability> mCapability;
+
+    // Logger
+    shared_ptr<vshl::common::interfaces::ILogger> mLogger;
+};
+
+}  // namespace core
+}  // namespace capabilities
+}  // namespace vshl
+
+#endif  // VSHL_CAPABILITIES_CORE_PUBLISHERFORWARDER_H_
diff --git a/src/plugins/capabilities/core/include/SubscriberForwarder.h b/src/plugins/capabilities/core/include/SubscriberForwarder.h
new file mode 100644
index 0000000..94c04bf
--- /dev/null
+++ b/src/plugins/capabilities/core/include/SubscriberForwarder.h
@@ -0,0 +1,84 @@
+/*
+ * Copyright 2018-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *     http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+#ifndef VSHL_CAPABILITIES_CORE_SUBSCRIBERFORWARDER_H_
+#define VSHL_CAPABILITIES_CORE_SUBSCRIBERFORWARDER_H_
+
+#include <memory>
+#include <string>
+#include <unordered_map>
+
+#include "interfaces/afb/IAFBApi.h"
+#include "interfaces/capabilities/ICapability.h"
+#include "interfaces/utilities/logging/ILogger.h"
+
+using namespace std;
+
+namespace vshl {
+namespace capabilities {
+namespace core {
+/*
+ * This class is responsible for forwarding the messages publishing
+ * to the actual clients using AFB.
+ */
+class SubscriberForwarder {
+public:
+  // Create a SubscriberForwarder.
+  static std::shared_ptr<SubscriberForwarder>
+  create(shared_ptr<vshl::common::interfaces::ILogger> logger,
+         shared_ptr<vshl::common::interfaces::IAFBApi> afbApi,
+         shared_ptr<vshl::common::interfaces::ICapability> capability);
+
+  // Publish a capability message to the actual client.
+  bool forwardMessage(const string action, const string payload);
+
+  // Subscribe
+  bool subscribe(vshl::common::interfaces::IAFBRequest &request,
+                 const string action);
+
+  // Destructor
+  ~SubscriberForwarder();
+
+private:
+  // Constructor
+  SubscriberForwarder(
+      shared_ptr<vshl::common::interfaces::ILogger> logger,
+      shared_ptr<vshl::common::interfaces::IAFBApi> afbApi,
+      shared_ptr<vshl::common::interfaces::ICapability> capability);
+
+  // Creates both upstream and downstream events
+  void createEvents();
+
+  // Binding API reference
+  shared_ptr<vshl::common::interfaces::IAFBApi> mAfbApi;
+
+  // Capability
+  shared_ptr<vshl::common::interfaces::ICapability> mCapability;
+
+  // Maps of capability action events to its corresponding Event object.
+  // Event name maps to Action Name
+  unordered_map<string, shared_ptr<common::interfaces::IAFBApi::IAFBEvent>>
+      mUpstreamEventsMap;
+  unordered_map<string, shared_ptr<common::interfaces::IAFBApi::IAFBEvent>>
+      mDownstreamEventsMap;
+
+  // Logger
+  shared_ptr<vshl::common::interfaces::ILogger> mLogger;
+};
+
+} // namespace core
+} // namespace capabilities
+} // namespace vshl
+
+#endif // VSHL_CAPABILITIES_CORE_SUBSCRIBERFORWARDER_H_
diff --git a/src/plugins/capabilities/core/src/MessageChannel.cpp b/src/plugins/capabilities/core/src/MessageChannel.cpp
new file mode 100644
index 0000000..eaa1349
--- /dev/null
+++ b/src/plugins/capabilities/core/src/MessageChannel.cpp
@@ -0,0 +1,51 @@
+/*
+ * Copyright 2018-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *     http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+#include "capabilities/core/include/MessageChannel.h"
+
+namespace vshl {
+namespace capabilities {
+namespace core {
+
+// Create a MessageChannel.
+std::shared_ptr<MessageChannel> MessageChannel::create(
+    shared_ptr<vshl::common::interfaces::ILogger> logger,
+    shared_ptr<vshl::common::interfaces::IAFBApi> api,
+    shared_ptr<vshl::common::interfaces::ICapability> capability) {
+    auto messageChannel = std::shared_ptr<MessageChannel>(new MessageChannel(logger, api, capability));
+    return messageChannel;
+}
+
+MessageChannel::MessageChannel(
+    shared_ptr<vshl::common::interfaces::ILogger> logger,
+    shared_ptr<vshl::common::interfaces::IAFBApi> api,
+    shared_ptr<vshl::common::interfaces::ICapability> capability) {
+    // Subscriber forwarder
+    mSubscriberForwarder = SubscriberForwarder::create(logger, api, capability);
+    // Publisher forwarder
+    mPublisherForwarder = PublisherForwarder::create(logger, capability);
+    mPublisherForwarder->setSubscriberForwarder(mSubscriberForwarder);
+}
+
+bool MessageChannel::publish(const string action, const string payload) {
+    return mPublisherForwarder->forwardMessage(action, payload);
+}
+
+bool MessageChannel::subscribe(vshl::common::interfaces::IAFBRequest& request, const string action) {
+    return mSubscriberForwarder->subscribe(request, action);
+}
+
+}  // namespace core
+}  // namespace capabilities
+}  // namespace vshl
diff --git a/src/plugins/capabilities/core/src/PublisherForwarder.cpp b/src/plugins/capabilities/core/src/PublisherForwarder.cpp
new file mode 100644
index 0000000..81de6a0
--- /dev/null
+++ b/src/plugins/capabilities/core/src/PublisherForwarder.cpp
@@ -0,0 +1,69 @@
+/*
+ * Copyright 2018-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *     http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+#include "capabilities/core/include/PublisherForwarder.h"
+
+static string TAG = "vshl::capabilities::PublisherForwarder";
+
+using Level = vshl::common::interfaces::ILogger::Level;
+
+namespace vshl {
+namespace capabilities {
+namespace core {
+
+// Create a PublisherForwarder.
+std::shared_ptr<PublisherForwarder> PublisherForwarder::create(
+    shared_ptr<vshl::common::interfaces::ILogger> logger,
+    shared_ptr<vshl::common::interfaces::ICapability> capability) {
+    if (logger == nullptr) {
+        return nullptr;
+    }
+
+    if (capability == nullptr) {
+        logger->log(Level::ERROR, TAG, "Failed to create PublisherForwarder: Capability null");
+        return nullptr;
+    }
+
+    auto publisherForwarder = std::shared_ptr<PublisherForwarder>(new PublisherForwarder(logger, capability));
+    return publisherForwarder;
+}
+
+// Constructor
+PublisherForwarder::PublisherForwarder(
+    shared_ptr<vshl::common::interfaces::ILogger> logger,
+    shared_ptr<vshl::common::interfaces::ICapability> capability) {
+    mCapability = capability;
+    mLogger = logger;
+}
+
+// Destructor
+PublisherForwarder::~PublisherForwarder() {
+}
+
+void PublisherForwarder::setSubscriberForwarder(shared_ptr<SubscriberForwarder> subscriberForwarder) {
+    mSubscriberForwarder = subscriberForwarder;
+}
+
+bool PublisherForwarder::forwardMessage(const string action, const string payload) {
+    if (!mSubscriberForwarder) {
+        mLogger->log(Level::ERROR, TAG, "Failed to forward message for capability: " + mCapability->getName());
+        return false;
+    }
+
+    return mSubscriberForwarder->forwardMessage(action, payload);
+}
+
+}  // namespace core
+}  // namespace capabilities
+}  // namespace vshl
diff --git a/src/plugins/capabilities/core/src/SubscriberForwarder.cpp b/src/plugins/capabilities/core/src/SubscriberForwarder.cpp
new file mode 100644
index 0000000..ea42305
--- /dev/null
+++ b/src/plugins/capabilities/core/src/SubscriberForwarder.cpp
@@ -0,0 +1,139 @@
+/*
+ * Copyright 2018-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *     http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+#include "capabilities/core/include/SubscriberForwarder.h"
+
+static string TAG = "vshl::capabilities::SubscriberForwarder";
+
+using Level = vshl::common::interfaces::ILogger::Level;
+
+namespace vshl {
+namespace capabilities {
+namespace core {
+
+// Create a SubscriberForwarder.
+std::shared_ptr<SubscriberForwarder> SubscriberForwarder::create(
+    shared_ptr<vshl::common::interfaces::ILogger> logger,
+    shared_ptr<vshl::common::interfaces::IAFBApi> afbApi,
+    shared_ptr<vshl::common::interfaces::ICapability> capability) {
+    if (logger == nullptr) {
+        return nullptr;
+    }
+
+    if (afbApi == nullptr) {
+        logger->log(Level::ERROR, TAG, "Failed to create SubscriberForwarder: AFB API null");
+        return nullptr;
+    }
+
+    if (capability == nullptr) {
+        logger->log(Level::ERROR, TAG, "Failed to create SubscriberForwarder: Capability null");
+        return nullptr;
+    }
+
+    auto subscriberForwarder =
+        std::shared_ptr<SubscriberForwarder>(new SubscriberForwarder(logger, afbApi, capability));
+    return subscriberForwarder;
+}
+
+SubscriberForwarder::SubscriberForwarder(
+    shared_ptr<vshl::common::interfaces::ILogger> logger,
+    shared_ptr<vshl::common::interfaces::IAFBApi> afbApi,
+    shared_ptr<vshl::common::interfaces::ICapability> capability) :
+        mAfbApi(afbApi),
+        mLogger(logger),
+        mCapability(capability) {
+    createEvents();
+}
+
+SubscriberForwarder::~SubscriberForwarder() {
+    mUpstreamEventsMap.clear();
+    mDownstreamEventsMap.clear();
+}
+
+void SubscriberForwarder::createEvents() {
+    if (!mCapability) {
+        mLogger->log(Level::NOTICE, TAG, "Create Events failed. No capability assigned.");
+        return;
+    }
+
+    // Upstream events
+    auto upstreamEvents = mCapability->getUpstreamMessages();
+    for (auto upstreamEventName : upstreamEvents) {
+        auto it = mUpstreamEventsMap.find(upstreamEventName);
+        if (it == mUpstreamEventsMap.end() && mAfbApi) {
+            // create a new event and add it to the map.
+            shared_ptr<common::interfaces::IAFBApi::IAFBEvent> event = mAfbApi->createEvent(upstreamEventName);
+            if (event == nullptr) {
+                mLogger->log(Level::ERROR, TAG, "Failed to create upstream event: " + upstreamEventName);
+            } else {
+                mUpstreamEventsMap.insert(make_pair(upstreamEventName, event));
+            }
+        }
+    }
+
+    // Downstream events
+    auto downstreamEvents = mCapability->getDownstreamMessages();
+    for (auto downstreamEventName : downstreamEvents) {
+        auto it = mDownstreamEventsMap.find(downstreamEventName);
+        if (it == mDownstreamEventsMap.end() && mAfbApi) {
+            // create a new event and add it to the map.
+            shared_ptr<common::interfaces::IAFBApi::IAFBEvent> event = mAfbApi->createEvent(downstreamEventName);
+            if (event == nullptr) {
+                mLogger->log(Level::ERROR, TAG, "Failed to create downstream event: " + downstreamEventName);
+            } else {
+                mDownstreamEventsMap.insert(make_pair(downstreamEventName, event));
+            }
+        }
+    }
+}
+
+bool SubscriberForwarder::forwardMessage(const string action, const string payload) {
+    auto upstreamEventIt = mUpstreamEventsMap.find(action);
+    if (upstreamEventIt != mUpstreamEventsMap.end()) {
+        mLogger->log(Level::NOTICE, TAG, "Publishing upstream event: " + action);
+        upstreamEventIt->second->publishEvent(json_object_new_string(payload.c_str()));
+        return true;
+    }
+
+    auto downstreamEventIt = mDownstreamEventsMap.find(action);
+    if (downstreamEventIt != mDownstreamEventsMap.end()) {
+        mLogger->log(Level::NOTICE, TAG, "Publishing downstream event: " + action);
+        downstreamEventIt->second->publishEvent(json_object_new_string(payload.c_str()));
+        return true;
+    }
+
+    mLogger->log(Level::NOTICE, TAG, "Failed to publish upstream event: " + action);
+    return false;
+}
+
+bool SubscriberForwarder::subscribe(vshl::common::interfaces::IAFBRequest& request, const string action) {
+    auto upstreamEventIt = mUpstreamEventsMap.find(action);
+    if (upstreamEventIt != mUpstreamEventsMap.end()) {
+        mLogger->log(Level::NOTICE, TAG, "Subscribing to upstream event: " + action);
+        return upstreamEventIt->second->subscribe(request);
+    }
+
+    auto downstreamEventIt = mDownstreamEventsMap.find(action);
+    if (downstreamEventIt != mDownstreamEventsMap.end()) {
+        mLogger->log(Level::NOTICE, TAG, "Subscribing to downstream event: " + action);
+        return downstreamEventIt->second->subscribe(request);
+    }
+
+    mLogger->log(Level::NOTICE, TAG, "Failed to subscribe to upstream event: " + action);
+    return false;
+}
+
+}  // namespace core
+}  // namespace capabilities
+}  // namespace vshl
diff --git a/src/plugins/capabilities/guimetadata/include/GuiMetadataCapability.h b/src/plugins/capabilities/guimetadata/include/GuiMetadataCapability.h
new file mode 100644
index 0000000..199f49a
--- /dev/null
+++ b/src/plugins/capabilities/guimetadata/include/GuiMetadataCapability.h
@@ -0,0 +1,52 @@
+/*
+ * Copyright 2018-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *     http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+
+#ifndef VSHL_CAPABILITIES_GUIMETADATA_CAPABILITY_H_
+#define VSHL_CAPABILITIES_GUIMETADATA_CAPABILITY_H_
+
+#include <memory>
+
+#include "interfaces/capabilities/ICapability.h"
+
+namespace vshl {
+namespace capabilities {
+namespace guimetadata {
+
+/*
+ * GuiMetadata capability
+ */
+class GuiMetadata : public common::interfaces::ICapability {
+public:
+    // Create a GuiMetadata.
+    static std::shared_ptr<GuiMetadata> create();
+
+    ~GuiMetadata() = default;
+
+protected:
+    string getName() const override;
+
+    list<string> getUpstreamMessages() const override;
+
+    list<string> getDownstreamMessages() const override;
+
+private:
+    GuiMetadata() = default;
+};
+
+}  // namespace guimetadata
+}  // namespace capabilities
+}  // namespace vshl
+
+#endif  // VSHL_CAPABILITIES_GUIMETADATA_CAPABILITY_H_
diff --git a/src/plugins/capabilities/guimetadata/include/GuiMetadataMessages.h b/src/plugins/capabilities/guimetadata/include/GuiMetadataMessages.h
new file mode 100644
index 0000000..783b401
--- /dev/null
+++ b/src/plugins/capabilities/guimetadata/include/GuiMetadataMessages.h
@@ -0,0 +1,50 @@
+/*
+ * Copyright 2018-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *     http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+#ifndef VSHL_CAPABILITIES_GUIMETADATA_ACTIONS_H_
+#define VSHL_CAPABILITIES_GUIMETADATA_ACTIONS_H_
+
+#include <list>
+#include <string>
+
+using namespace std;
+
+namespace vshl {
+namespace capabilities {
+namespace guimetadata {
+
+static string NAME = "guimetadata";
+
+// Supported actions from VA -> Apps
+static string GUIMETADATA_RENDER_TEMPLATE = "render_template";
+static string GUIMETADATA_CLEAR_TEMPLATE = "clear_template";
+static string GUIMETADATA_RENDER_PLAYER_INFO = "render_player_info";
+static string GUIMETADATA_CLEAR_PLAYER_INFO = "clear_player_info";
+
+// Supported actions from Apps -> VA
+
+// List of actions that are delivered from VA -> Apps
+static list<string> GUIMETADATA_UPSTREAM_ACTIONS = {GUIMETADATA_RENDER_TEMPLATE,
+                                                    GUIMETADATA_CLEAR_TEMPLATE,
+                                                    GUIMETADATA_RENDER_PLAYER_INFO,
+                                                    GUIMETADATA_CLEAR_PLAYER_INFO};
+
+// List of actions that are delivered from Apps -> VA
+static list<string> GUIMETADATA_DOWNSTREAM_ACTIONS = {};
+
+}  // namespace guimetadata
+}  // namespace capabilities
+}  // namespace vshl
+
+#endif  // VSHL_CAPABILITIES_GUIMETADATA_ACTIONS_H_
diff --git a/src/plugins/capabilities/guimetadata/src/GuiMetadataCapability.cpp b/src/plugins/capabilities/guimetadata/src/GuiMetadataCapability.cpp
new file mode 100644
index 0000000..106fe99
--- /dev/null
+++ b/src/plugins/capabilities/guimetadata/src/GuiMetadataCapability.cpp
@@ -0,0 +1,42 @@
+/*
+ * Copyright 2018-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *     http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+#include "capabilities/guimetadata/include/GuiMetadataCapability.h"
+#include "capabilities/guimetadata/include/GuiMetadataMessages.h"
+
+namespace vshl {
+namespace capabilities {
+namespace guimetadata {
+
+// Create a GuiMetadata.
+shared_ptr<GuiMetadata> GuiMetadata::create() {
+    auto guiMetadata = std::shared_ptr<GuiMetadata>(new GuiMetadata());
+    return guiMetadata;
+}
+
+string GuiMetadata::getName() const {
+    return NAME;
+}
+
+list<string> GuiMetadata::getUpstreamMessages() const {
+    return GUIMETADATA_UPSTREAM_ACTIONS;
+}
+
+list<string> GuiMetadata::getDownstreamMessages() const {
+    return GUIMETADATA_DOWNSTREAM_ACTIONS;
+}
+
+}  // namespace guimetadata
+}  // namespace capabilities
+}  // namespace vshl
diff --git a/src/plugins/capabilities/navigation/include/NavigationCapability.h b/src/plugins/capabilities/navigation/include/NavigationCapability.h
new file mode 100644
index 0000000..66109d5
--- /dev/null
+++ b/src/plugins/capabilities/navigation/include/NavigationCapability.h
@@ -0,0 +1,52 @@
+/*
+ * Copyright 2018-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *     http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+
+#ifndef VSHL_CAPABILITIES_NAVIGATION_CAPABILITY_H_
+#define VSHL_CAPABILITIES_NAVIGATION_CAPABILITY_H_
+
+#include <memory>
+
+#include "interfaces/capabilities/ICapability.h"
+
+namespace vshl {
+namespace capabilities {
+namespace navigation {
+
+/*
+ * Navigation capability
+ */
+class Navigation : public common::interfaces::ICapability {
+public:
+  // Create a Navigation.
+  static std::shared_ptr<Navigation> create();
+
+  ~Navigation() = default;
+
+protected:
+  string getName() const override;
+
+  list<string> getUpstreamMessages() const override;
+
+  list<string> getDownstreamMessages() const override;
+
+private:
+  Navigation() = default;
+};
+
+} // namespace navigation
+} // namespace capabilities
+} // namespace vshl
+
+#endif // VSHL_CAPABILITIES_NAVIGATION_CAPABILITY_H_
diff --git a/src/plugins/capabilities/navigation/include/NavigationMessages.h b/src/plugins/capabilities/navigation/include/NavigationMessages.h
new file mode 100644
index 0000000..aed9b9e
--- /dev/null
+++ b/src/plugins/capabilities/navigation/include/NavigationMessages.h
@@ -0,0 +1,48 @@
+/*
+ * Copyright 2018-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *     http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+#ifndef VSHL_CAPABILITIES_NAVIGATION_ACTIONS_H_
+#define VSHL_CAPABILITIES_NAVIGATION_ACTIONS_H_
+
+#include <list>
+#include <string>
+
+using namespace std;
+
+namespace vshl {
+namespace capabilities {
+namespace navigation {
+
+static string NAME = "navigation";
+
+// Supported actions from VA -> Apps
+static string NAVIGATION_SET_DESTINATION = "set_destination";
+static string NAVIGATION_CANCEL = "cancel_navigation";
+
+// Supported actions from Apps -> VA
+
+// List of actions that are delivered from VA -> Apps
+static list<string> NAVIGATION_UPSTREAM_ACTIONS = {
+    NAVIGATION_SET_DESTINATION,
+    NAVIGATION_CANCEL,
+};
+
+// List of actions that are delivered from Apps -> VA
+static list<string> NAVIGATION_DOWNSTREAM_ACTIONS = {};
+
+}  // namespace navigation
+}  // namespace capabilities
+}  // namespace vshl
+
+#endif  // VSHL_CAPABILITIES_NAVIGATION_ACTIONS_H_
diff --git a/src/plugins/capabilities/navigation/src/NavigationCapability.cpp b/src/plugins/capabilities/navigation/src/NavigationCapability.cpp
new file mode 100644
index 0000000..d4a5119
--- /dev/null
+++ b/src/plugins/capabilities/navigation/src/NavigationCapability.cpp
@@ -0,0 +1,42 @@
+/*
+ * Copyright 2018-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *     http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+#include "capabilities/navigation/include/NavigationCapability.h"
+#include "capabilities/navigation/include/NavigationMessages.h"
+
+namespace vshl {
+namespace capabilities {
+namespace navigation {
+
+// Create a Navigation.
+shared_ptr<Navigation> Navigation::create() {
+    auto navigation = std::shared_ptr<Navigation>(new Navigation());
+    return navigation;
+}
+
+string Navigation::getName() const {
+    return NAME;
+}
+
+list<string> Navigation::getUpstreamMessages() const {
+    return NAVIGATION_UPSTREAM_ACTIONS;
+}
+
+list<string> Navigation::getDownstreamMessages() const {
+    return NAVIGATION_DOWNSTREAM_ACTIONS;
+}
+
+}  // namespace navigation
+}  // namespace capabilities
+}  // namespace vshl
diff --git a/src/plugins/capabilities/test/CapabilityMessagingServiceTest.cpp b/src/plugins/capabilities/test/CapabilityMessagingServiceTest.cpp
new file mode 100644
index 0000000..741a8aa
--- /dev/null
+++ b/src/plugins/capabilities/test/CapabilityMessagingServiceTest.cpp
@@ -0,0 +1,96 @@
+/*
+ * Copyright 2018-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *     http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+#include <gtest/gtest.h>
+
+#include "capabilities/CapabilityMessagingService.h"
+
+#include "test/common/ConsoleLogger.h"
+#include "test/mocks/AFBApiMock.h"
+#include "test/mocks/AFBEventMock.h"
+#include "test/mocks/AFBRequestMock.h"
+#include "test/mocks/CapabilityMock.h"
+
+using namespace vshl::common::interfaces;
+using namespace vshl::capabilities;
+using namespace vshl::test::common;
+
+namespace vshl {
+namespace test {
+
+class CapabilityMessagingServiceTest : public ::testing::Test {
+protected:
+    void SetUp() override {
+        mConsoleLogger = std::make_shared<ConsoleLogger>();
+        mAfbApi = std::make_shared<::testing::NiceMock<AFBApiMock>>();
+    }
+
+    std::shared_ptr<::testing::NiceMock<AFBApiMock>> mAfbApi;
+    std::shared_ptr<ConsoleLogger> mConsoleLogger;
+};
+
+TEST_F(CapabilityMessagingServiceTest, failsInitializationOnInvalidParams) {
+    auto service = CapabilityMessagingService::create(mConsoleLogger, nullptr);
+    ASSERT_EQ(service, nullptr);
+
+    service = CapabilityMessagingService::create(nullptr, mAfbApi);
+    ASSERT_EQ(service, nullptr);
+}
+
+TEST_F(CapabilityMessagingServiceTest, initializesSuccessfully) {
+    auto service = CapabilityMessagingService::create(mConsoleLogger, mAfbApi);
+    ASSERT_NE(service, nullptr);
+}
+
+TEST_F(CapabilityMessagingServiceTest, canSubscribeAndPublishCapabilityEvents) {
+    auto service = CapabilityMessagingService::create(mConsoleLogger, mAfbApi);
+
+    auto capability = std::make_shared<::testing::NiceMock<CapabilityMock>>();
+    std::list<std::string> upstreamEvents({"up-ev1", "up-ev2"});
+    std::list<std::string> downstreamEvents({"down-ev1", "down-ev2"});
+    std::string capabilityName = "weather";
+
+    ON_CALL(*capability, getName()).WillByDefault(::testing::Return(capabilityName));
+    ON_CALL(*capability, getUpstreamMessages()).WillByDefault(::testing::Return(upstreamEvents));
+    ON_CALL(*capability, getDownstreamMessages()).WillByDefault(::testing::Return(downstreamEvents));
+
+    // We don't care if and how many times subscribe method is called on event.
+    std::shared_ptr<AFBEventMock> mockEvent(new ::testing::NiceMock<AFBEventMock>());
+    ON_CALL(*mockEvent, subscribe(::testing::_)).WillByDefault(::testing::Return(true));
+    ON_CALL(*mockEvent, publishEvent(::testing::_)).WillByDefault(::testing::Return(true));
+    auto eventCreator = [mockEvent](const std::string& eventName) -> std::shared_ptr<IAFBApi::IAFBEvent> {
+        mockEvent->setName(eventName);
+        return mockEvent;
+    };
+
+    ON_CALL(*mAfbApi, createEvent(::testing::_)).WillByDefault(::testing::Invoke(eventCreator));
+
+    auto request = std::make_shared<::testing::StrictMock<AFBRequestMock>>();
+    std::string payload = "The answer to life the universe and everything = 42";
+
+    bool result = service->publish(capability, *upstreamEvents.begin(), payload);
+    ASSERT_FALSE(result);  // Without subscribing to the event. Publish should fail.
+
+    result = service->subscribe(*request, capability, *upstreamEvents.begin());
+    ASSERT_TRUE(result);
+
+    result = service->subscribe(*request, capability, *downstreamEvents.begin());
+    ASSERT_TRUE(result);
+
+    result = service->publish(capability, *downstreamEvents.begin(), payload);
+    ASSERT_TRUE(result);
+}
+
+}  // namespace test
+}  // namespace vshl
\ No newline at end of file
diff --git a/src/plugins/capabilities/test/PublisherForwarderTest.cpp b/src/plugins/capabilities/test/PublisherForwarderTest.cpp
new file mode 100644
index 0000000..d0ba319
--- /dev/null
+++ b/src/plugins/capabilities/test/PublisherForwarderTest.cpp
@@ -0,0 +1,116 @@
+/*
+ * Copyright 2018-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *     http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+#include <gtest/gtest.h>
+
+#include "capabilities/core/include/PublisherForwarder.h"
+#include "capabilities/core/include/SubscriberForwarder.h"
+
+#include "test/common/ConsoleLogger.h"
+#include "test/mocks/AFBApiMock.h"
+#include "test/mocks/AFBEventMock.h"
+#include "test/mocks/CapabilityMock.h"
+
+using namespace vshl::common::interfaces;
+using namespace vshl::capabilities::core;
+using namespace vshl::test::common;
+
+namespace vshl {
+namespace test {
+
+class PublisherForwarderTest : public ::testing::Test {
+protected:
+    void SetUp() override {
+        mConsoleLogger = std::make_shared<ConsoleLogger>();
+        mAfbApi = std::make_shared<::testing::StrictMock<AFBApiMock>>();
+
+        mEventCreatorFn = [](const std::string& eventName) -> std::shared_ptr<IAFBApi::IAFBEvent> {
+            std::shared_ptr<AFBEventMock> mockEvent(new ::testing::StrictMock<AFBEventMock>());
+            mockEvent->setName(eventName);
+            return mockEvent;
+        };
+    }
+
+    std::shared_ptr<SubscriberForwarder> createSubscriberForwarder(
+        std::shared_ptr<::testing::StrictMock<CapabilityMock>> capability) {
+        EXPECT_CALL(*capability, getUpstreamMessages()).Times(1);
+        EXPECT_CALL(*capability, getDownstreamMessages()).Times(1);
+
+        return SubscriberForwarder::create(mConsoleLogger, mAfbApi, capability);
+    }
+
+    std::shared_ptr<PublisherForwarder> createPublisherForwarder(
+        std::shared_ptr<::testing::StrictMock<CapabilityMock>> capability) {
+        return PublisherForwarder::create(mConsoleLogger, capability);
+    }
+
+    std::shared_ptr<::testing::StrictMock<AFBApiMock>> mAfbApi;
+    std::shared_ptr<ConsoleLogger> mConsoleLogger;
+    std::function<std::shared_ptr<IAFBApi::IAFBEvent>(const std::string&)> mEventCreatorFn;
+    std::shared_ptr<::testing::StrictMock<AFBEventMock>> mAfbEventMock;
+};
+
+TEST_F(PublisherForwarderTest, failsInitializationOnInvalidParams) {
+    auto capability = std::make_shared<::testing::StrictMock<CapabilityMock>>();
+
+    auto forwarder = PublisherForwarder::create(mConsoleLogger, nullptr);
+    ASSERT_EQ(forwarder, nullptr);
+
+    forwarder = PublisherForwarder::create(nullptr, capability);
+    ASSERT_EQ(forwarder, nullptr);
+}
+
+TEST_F(PublisherForwarderTest, initializesCorrectly) {
+    auto capability = std::make_shared<::testing::StrictMock<CapabilityMock>>();
+    auto forwarder = createPublisherForwarder(capability);
+
+    ASSERT_NE(forwarder, nullptr);
+}
+
+TEST_F(PublisherForwarderTest, canForwardMessages) {
+    std::shared_ptr<AFBEventMock> mockEvent(new ::testing::StrictMock<AFBEventMock>());
+    ON_CALL(*mockEvent, publishEvent(::testing::_)).WillByDefault(::testing::Return(true));
+    EXPECT_CALL(*mockEvent, publishEvent(::testing::_)).Times(4);
+    auto eventCreator = [mockEvent](const std::string& eventName) -> std::shared_ptr<IAFBApi::IAFBEvent> {
+        return mockEvent;
+    };
+
+    ON_CALL(*mAfbApi, createEvent(::testing::_)).WillByDefault(::testing::Invoke(eventCreator));
+    EXPECT_CALL(*mAfbApi, createEvent(::testing::_)).Times(4);
+
+    auto capability = std::make_shared<::testing::StrictMock<CapabilityMock>>();
+    std::list<std::string> upstreamEvents({"up-ev1", "up-ev2"});
+    std::list<std::string> downstreamEvents({"down-ev1", "down-ev2"});
+    ON_CALL(*capability, getUpstreamMessages()).WillByDefault(::testing::Return(upstreamEvents));
+    ON_CALL(*capability, getDownstreamMessages()).WillByDefault(::testing::Return(downstreamEvents));
+
+    auto publisherForwarder = createPublisherForwarder(capability);
+    ASSERT_NE(publisherForwarder, nullptr);
+
+    auto subscriberForwarder = createSubscriberForwarder(capability);
+    ASSERT_NE(subscriberForwarder, nullptr);
+
+    std::string payload = "The answer to life the universe and everything = 42";
+    publisherForwarder->setSubscriberForwarder(subscriberForwarder);
+
+    auto itCapability = downstreamEvents.begin();
+    ASSERT_TRUE(publisherForwarder->forwardMessage(*itCapability++, payload));
+    ASSERT_TRUE(publisherForwarder->forwardMessage(*itCapability++, payload));
+    itCapability = upstreamEvents.begin();
+    ASSERT_TRUE(publisherForwarder->forwardMessage(*itCapability++, payload));
+    ASSERT_TRUE(publisherForwarder->forwardMessage(*itCapability++, payload));
+}
+
+}  // namespace test
+}  // namespace vshl
\ No newline at end of file
diff --git a/src/plugins/capabilities/test/SubscriberForwarderTest.cpp b/src/plugins/capabilities/test/SubscriberForwarderTest.cpp
new file mode 100644
index 0000000..ff438df
--- /dev/null
+++ b/src/plugins/capabilities/test/SubscriberForwarderTest.cpp
@@ -0,0 +1,262 @@
+/*
+ * Copyright 2018-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *     http://aws.amazon.com/apache2.0/
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+#include <gtest/gtest.h>
+
+#include "capabilities/core/include/SubscriberForwarder.h"
+
+#include "test/common/ConsoleLogger.h"
+#include "test/mocks/AFBApiMock.h"
+#include "test/mocks/AFBEventMock.h"
+#include "test/mocks/AFBRequestMock.h"
+#include "test/mocks/CapabilityMock.h"
+
+using namespace vshl::common::interfaces;
+using namespace vshl::capabilities::core;
+using namespace vshl::test::common;
+
+namespace vshl {
+namespace test {
+
+class SubscriberForwarderTest : public ::testing::Test {
+protected:
+    void SetUp() override {
+        mConsoleLogger = std::make_shared<ConsoleLogger>();
+        mAfbApi = std::make_shared<::testing::StrictMock<AFBApiMock>>();
+
+        mEventCreatorFn = [](const std::string& eventName) -> std::shared_ptr<IAFBApi::IAFBEvent> {
+            std::shared_ptr<AFBEventMock> mockEvent(new ::testing::StrictMock<AFBEventMock>());
+            mockEvent->setName(eventName);
+            return mockEvent;
+        };
+    }
+
+    std::shared_ptr<SubscriberForwarder> createSubscriberForwarder(
+        std::shared_ptr<::testing::StrictMock<CapabilityMock>> capability) {
+        EXPECT_CALL(*capability, getUpstreamMessages()).Times(1);
+        EXPECT_CALL(*capability, getDownstreamMessages()).Times(1);
+
+        return SubscriberForwarder::create(mConsoleLogger, mAfbApi, capability);
+    }
+
+    std::shared_ptr<::testing::StrictMock<AFBApiMock>> mAfbApi;
+    std::shared_ptr<ConsoleLogger> mConsoleLogger;
+    std::function<std::shared_ptr<IAFBApi::IAFBEvent>(const std::string&)> mEventCreatorFn;
+    std::shared_ptr<::testing::StrictMock<AFBEventMock>> mAfbEventMock;
+};
+
+TEST_F(SubscriberForwarderTest, failsInitializationOnInvalidParams) {
+    auto capability = std::make_shared<::testing::StrictMock<CapabilityMock>>();
+
+    auto forwarder = SubscriberForwarder::create(mConsoleLogger, mAfbApi, nullptr);
+    ASSERT_EQ(forwarder, nullptr);
+
+    forwarder = SubscriberForwarder::create(mConsoleLogger, nullptr, capability);
+    ASSERT_EQ(forwarder, nullptr);
+
+    forwarder = SubscriberForwarder::create(nullptr, mAfbApi, capability);
+    ASSERT_EQ(forwarder, nullptr);
+}
+
+TEST_F(SubscriberForwarderTest, initializesCorrectly) {
+    auto capability = std::make_shared<::testing::StrictMock<CapabilityMock>>();
+    auto forwarder = createSubscriberForwarder(capability);
+
+    ASSERT_NE(forwarder, nullptr);
+}
+
+TEST_F(SubscriberForwarderTest, createsEventsOnInitialization) {
+    ON_CALL(*mAfbApi, createEvent(::testing::_)).WillByDefault(::testing::Invoke(mEventCreatorFn));
+
+    std::list<std::string> upstreamEvents({"up-ev1", "up-ev2"});
+    std::list<std::string> downstreamEvents({"down-ev1", "down-ev2"});
+
+    auto capability = std::make_shared<::testing::StrictMock<CapabilityMock>>();
+    ON_CALL(*capability, getUpstreamMessages()).WillByDefault(::testing::Return(upstreamEvents));
+    ON_CALL(*capability, getDownstreamMessages()).WillByDefault(::testing::Return(downstreamEvents));
+
+    auto itCapability = upstreamEvents.begin();
+    EXPECT_CALL(*mAfbApi, createEvent(*itCapability)).Times(1);
+    itCapability++;
+    EXPECT_CALL(*mAfbApi, createEvent(*itCapability)).Times(1);
+
+    itCapability = downstreamEvents.begin();
+    EXPECT_CALL(*mAfbApi, createEvent(*itCapability)).Times(1);
+    itCapability++;
+    EXPECT_CALL(*mAfbApi, createEvent(*itCapability)).Times(1);
+
+    auto forwarder = createSubscriberForwarder(capability);
+    ASSERT_NE(forwarder, nullptr);
+}
+
+TEST_F(SubscriberForwarderTest, canNotSubscribeToNonExistentEvents) {
+    ON_CALL(*mAfbApi, createEvent(::testing::_)).WillByDefault(::testing::Invoke(mEventCreatorFn));
+    EXPECT_CALL(*mAfbApi, createEvent(::testing::_)).Times(4);
+
+    std::list<std::string> upstreamEvents({"up-ev1", "up-ev2"});
+    std::list<std::string> downstreamEvents({"down-ev1", "down-ev2"});
+
+    auto capability = std::make_shared<::testing::StrictMock<CapabilityMock>>();
+    ON_CALL(*capability, getUpstreamMessages()).WillByDefault(::testing::Return(upstreamEvents));
+    ON_CALL(*capability, getDownstreamMessages()).WillByDefault(::testing::Return(downstreamEvents));
+
+    auto forwarder = createSubscriberForwarder(capability);
+    ASSERT_NE(forwarder, nullptr);
+
+    auto nonExistentEvents = std::list<std::string>({"non", "existent", "events"});
+    auto itCapability = nonExistentEvents.begin();
+    auto request = std::make_shared<::testing::StrictMock<AFBRequestMock>>();
+    ASSERT_FALSE(forwarder->subscribe(*request, *itCapability++));
+    ASSERT_FALSE(forwarder->subscribe(*request, *itCapability++));
+    ASSERT_FALSE(forwarder->subscribe(*request, *itCapability++));
+}
+
+TEST_F(SubscriberForwarderTest, canNotSubscribeOnEventCreationFailure) {
+    // Fail the event creation and return null event.
+    ON_CALL(*mAfbApi, createEvent(::testing::_)).WillByDefault(::testing::Return(nullptr));
+    EXPECT_CALL(*mAfbApi, createEvent(::testing::_)).Times(4);
+
+    std::list<std::string> upstreamEvents({"up-ev1", "up-ev2"});
+    std::list<std::string> downstreamEvents({"down-ev1", "down-ev2"});
+
+    auto capability = std::make_shared<::testing::StrictMock<CapabilityMock>>();
+    ON_CALL(*capability, getUpstreamMessages()).WillByDefault(::testing::Return(upstreamEvents));
+    ON_CALL(*capability, getDownstreamMessages()).WillByDefault(::testing::Return(downstreamEvents));
+
+    auto forwarder = createSubscriberForwarder(capability);
+    ASSERT_NE(forwarder, nullptr);
+
+    auto itCapability = downstreamEvents.begin();
+    auto request = std::make_shared<::testing::StrictMock<AFBRequestMock>>();
+    std::string payload = "The answer to life the universe and everything = 42";
+    ASSERT_FALSE(forwarder->subscribe(*request, *itCapability++));
+    ASSERT_FALSE(forwarder->subscribe(*request, *itCapability++));
+    itCapability = upstreamEvents.begin();
+    ASSERT_FALSE(forwarder->subscribe(*request, *itCapability++));
+    ASSERT_FALSE(forwarder->subscribe(*request, *itCapability++));
+}
+
+TEST_F(SubscriberForwarderTest, canSubscribeToEvents) {
+    std::shared_ptr<AFBEventMock> mockEvent(new ::testing::StrictMock<AFBEventMock>());
+    ON_CALL(*mockEvent, subscribe(::testing::_)).WillByDefault(::testing::Return(true));
+    EXPECT_CALL(*mockEvent, subscribe(::testing::_)).Times(4);
+    auto eventCreator = [mockEvent](const std::string& eventName) -> std::shared_ptr<IAFBApi::IAFBEvent> {
+        return mockEvent;
+    };
+
+    ON_CALL(*mAfbApi, createEvent(::testing::_)).WillByDefault(::testing::Invoke(eventCreator));
+    EXPECT_CALL(*mAfbApi, createEvent(::testing::_)).Times(4);
+
+    std::list<std::string> upstreamEvents({"up-ev1", "up-ev2"});
+    std::list<std::string> downstreamEvents({"down-ev1", "down-ev2"});
+
+    auto capability = std::make_shared<::testing::StrictMock<CapabilityMock>>();
+    ON_CALL(*capability, getUpstreamMessages()).WillByDefault(::testing::Return(upstreamEvents));
+    ON_CALL(*capability, getDownstreamMessages()).WillByDefault(::testing::Return(downstreamEvents));
+
+    auto forwarder = createSubscriberForwarder(capability);
+    ASSERT_NE(forwarder, nullptr);
+
+    auto itCapability = downstreamEvents.begin();
+    auto request = std::make_shared<::testing::StrictMock<AFBRequestMock>>();
+    ASSERT_TRUE(forwarder->subscribe(*request, *itCapability++));
+    ASSERT_TRUE(forwarder->subscribe(*request, *itCapability));
+    itCapability = upstreamEvents.begin();
+    ASSERT_TRUE(forwarder->subscribe(*request, *itCapability++));
+    ASSERT_TRUE(forwarder->subscribe(*request, *itCapability));
+}
+
+TEST_F(SubscriberForwarderTest, canNotPublishNonExistentEvents) {
+    std::shared_ptr<AFBEventMock> mockEvent(new ::testing::StrictMock<AFBEventMock>());
+    EXPECT_CALL(*mockEvent, publishEvent(::testing::_)).Times(0);
+    auto eventCreator = [mockEvent](const std::string& eventName) -> std::shared_ptr<IAFBApi::IAFBEvent> {
+        return mockEvent;
+    };
+
+    ON_CALL(*mAfbApi, createEvent(::testing::_)).WillByDefault(::testing::Invoke(eventCreator));
+    EXPECT_CALL(*mAfbApi, createEvent(::testing::_)).Times(4);
+
+    std::list<std::string> upstreamEvents({"up-ev1", "up-ev2"});
+    std::list<std::string> downstreamEvents({"down-ev1", "down-ev2"});
+
+    auto capability = std::make_shared<::testing::StrictMock<CapabilityMock>>();
+    ON_CALL(*capability, getUpstreamMessages()).WillByDefault(::testing::Return(upstreamEvents));
+    ON_CALL(*capability, getDownstreamMessages()).WillByDefault(::testing::Return(downstreamEvents));
+
+    auto forwarder = createSubscriberForwarder(capability);
+    ASSERT_NE(forwarder, nullptr);
+
+    auto nonExistentEvents = std::list<std::string>({"non", "existent", "events"});
+    auto itCapability = nonExistentEvents.begin();
+    ASSERT_FALSE(forwarder->forwardMessage(*itCapability++, "My-Payload"));
+    ASSERT_FALSE(forwarder->forwardMessage(*itCapability++, "My-Payload"));
+    ASSERT_FALSE(forwarder->forwardMessage(*itCapability++, "My-Payload"));
+}
+
+TEST_F(SubscriberForwarderTest, canNotPublishOnEventCreationFailure) {
+    // Fail the event creation and return null event.
+    ON_CALL(*mAfbApi, createEvent(::testing::_)).WillByDefault(::testing::Return(nullptr));
+    EXPECT_CALL(*mAfbApi, createEvent(::testing::_)).Times(4);
+
+    std::list<std::string> upstreamEvents({"up-ev1", "up-ev2"});
+    std::list<std::string> downstreamEvents({"down-ev1", "down-ev2"});
+
+    auto capability = std::make_shared<::testing::StrictMock<CapabilityMock>>();
+    ON_CALL(*capability, getUpstreamMessages()).WillByDefault(::testing::Return(upstreamEvents));
+    ON_CALL(*capability, getDownstreamMessages()).WillByDefault(::testing::Return(downstreamEvents));
+
+    auto forwarder = createSubscriberForwarder(capability);
+    ASSERT_NE(forwarder, nullptr);
+
+    auto itCapability = downstreamEvents.begin();
+    std::string payload = "The answer to life the universe and everything = 42";
+    ASSERT_FALSE(forwarder->forwardMessage(*itCapability++, payload));
+    ASSERT_FALSE(forwarder->forwardMessage(*itCapability++, payload));
+    itCapability = upstreamEvents.begin();
+    ASSERT_FALSE(forwarder->forwardMessage(*itCapability++, payload));
+    ASSERT_FALSE(forwarder->forwardMessage(*itCapability++, payload));
+}
+
+TEST_F(SubscriberForwarderTest, canPublishEvents) {
+    std::shared_ptr<AFBEventMock> mockEvent(new ::testing::StrictMock<AFBEventMock>());
+    ON_CALL(*mockEvent, publishEvent(::testing::_)).WillByDefault(::testing::Return(true));
+    EXPECT_CALL(*mockEvent, publishEvent(::testing::_)).Times(4);
+    auto eventCreator = [mockEvent](const std::string& eventName) -> std::shared_ptr<IAFBApi::IAFBEvent> {
+        return mockEvent;
+    };
+
+    ON_CALL(*mAfbApi, createEvent(::testing::_)).WillByDefault(::testing::Invoke(eventCreator));
+    EXPECT_CALL(*mAfbApi, createEvent(::testing::_)).Times(4);
+
+    std::list<std::string> upstreamEvents({"up-ev1", "up-ev2"});
+    std::list<std::string> downstreamEvents({"down-ev1", "down-ev2"});
+
+    auto capability = std::make_shared<::testing::StrictMock<CapabilityMock>>();
+    ON_CALL(*capability, getUpstreamMessages()).WillByDefault(::testing::Return(upstreamEvents));
+    ON_CALL(*capability, getDownstreamMessages()).WillByDefault(::testing::Return(downstreamEvents));
+
+    auto forwarder = createSubscriberForwarder(capability);
+    ASSERT_NE(forwarder, nullptr);
+
+    auto itCapability = downstreamEvents.begin();
+    std::string payload = "The answer to life the universe and everything = 42";
+    ASSERT_TRUE(forwarder->forwardMessage(*itCapability++, payload));
+    ASSERT_TRUE(forwarder->forwardMessage(*itCapability++, payload));
+    itCapability = upstreamEvents.begin();
+    ASSERT_TRUE(forwarder->forwardMessage(*itCapability++, payload));
+    ASSERT_TRUE(forwarder->forwardMessage(*itCapability++, payload));
+}
+
+}  // namespace test
+}  // namespace vshl
\ No newline at end of file