Event Broadcasting

This functionality enables a skeleton to broadcast events to multiple proxy subscribers across different clusters and within the same cluster.

Static View

The following software units are involved in event broadcasting:

  • Transceiver Unit (Skeleton side): Manages event emission and subscriber tracking (see Proxy/Skeleton Base for its class diagram)

  • Transceiver Unit (Proxy side): Receives and processes broadcast events (see Proxy/Skeleton Base)

  • Message Management Unit: Allocates event messages with reference counting

  • Cluster Connection Unit: Routes events to subscribed clusters

  • Message Queue Unit: Delivers events to proxy cores

' ******************************************************************************* ' Copyright (c) 2026 BMW AG ' ' 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 ' ******************************************************************************* @startuml left to right direction skinparam linetype ortho component "Proxy/Skeleton Base" as event_broadcasting_proxy_skeleton_base component "Cluster Connection" as event_broadcasting_cluster_connection component "Message Management" as event_broadcasting_message_management component "Message Queue" as event_broadcasting_message_queue event_broadcasting_proxy_skeleton_base --> event_broadcasting_message_management event_broadcasting_proxy_skeleton_base --> event_broadcasting_cluster_connection event_broadcasting_cluster_connection --> event_broadcasting_message_queue event_broadcasting_cluster_connection --> event_broadcasting_proxy_skeleton_base event_broadcasting_message_management --> event_broadcasting_proxy_skeleton_base @enduml

Event broadcasting component view

Notes:

  • EventSender broadcasts to all registered cluster connections.

  • Each cluster has its own queue.

  • Externally allocated payload is reference-counted for multi-cluster delivery (ref_count = num clusters).

  • The last cluster to process the event deallocates the payload.

Dynamic View

The dynamic view illustrates event broadcasting from skeleton to multiple proxies with reference counting.

' ******************************************************************************* ' Copyright (c) 2026 BMW AG ' ' 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 ' ******************************************************************************* @startuml hide footbox actor "Generated\nSkeleton" as generated_skeleton participant "Proxy/Skeleton Base" as proxy_skeleton_base_unit participant "Message Management" as message_management_unit participant "Cluster Connection" as cluster_connection_unit participant "Message Queue" as message_queue_unit activate proxy_skeleton_base_unit activate message_management_unit note over proxy_skeleton_base_unit Skeleton side prepares an event for multiple target clusters. end note generated_skeleton -> proxy_skeleton_base_unit : send(eventData) proxy_skeleton_base_unit -> proxy_skeleton_base_unit : createEventMessage(memberId) proxy_skeleton_base_unit -> message_management_unit : allocate(data, msg, numClusters=2) message_management_unit -> message_management_unit : set ref_count = 2 message_management_unit --> proxy_skeleton_base_unit : HRESULT::Ok note over message_management_unit : Payload allocated with ref_count = 2. loop repeated for each target cluster proxy_skeleton_base_unit -> cluster_connection_unit : sendMessage(msg) activate cluster_connection_unit cluster_connection_unit -> message_queue_unit : push(msg) activate message_queue_unit message_queue_unit --> cluster_connection_unit : success deactivate message_queue_unit cluster_connection_unit --> proxy_skeleton_base_unit : HRESULT::Ok deactivate cluster_connection_unit end proxy_skeleton_base_unit --> generated_skeleton : HRESULT::Ok note over message_queue_unit : Event is delivered to multiple clusters. note over proxy_skeleton_base_unit Repeated per subscribing proxy cluster: receive event and decrease refcount. end note cluster_connection_unit -> message_queue_unit : pop(msg) activate cluster_connection_unit activate message_queue_unit message_queue_unit --> cluster_connection_unit : event msg deactivate message_queue_unit cluster_connection_unit -> proxy_skeleton_base_unit : onNewMessageReceived(msg) proxy_skeleton_base_unit -> proxy_skeleton_base_unit : invoke event callback proxy_skeleton_base_unit -> message_management_unit : decrementRefCount(msg) message_management_unit -> message_management_unit : ref_count = 1 note over message_management_unit : First subscriber keeps one remaining reference. deactivate cluster_connection_unit cluster_connection_unit -> message_queue_unit : pop(msg) activate cluster_connection_unit activate message_queue_unit message_queue_unit --> cluster_connection_unit : event msg deactivate message_queue_unit cluster_connection_unit -> proxy_skeleton_base_unit : onNewMessageReceived(msg) proxy_skeleton_base_unit -> proxy_skeleton_base_unit : invoke event callback proxy_skeleton_base_unit -> message_management_unit : decrementRefCount(msg) message_management_unit -> message_management_unit : ref_count = 0 message_management_unit -> message_management_unit : deallocate payload note over message_management_unit : Last reference released; payload is deallocated. deactivate cluster_connection_unit deactivate message_management_unit deactivate proxy_skeleton_base_unit @enduml

Event broadcasting sequence