github.com/jingruilea/kubeedge@v1.2.0-beta.0.0.20200410162146-4bb8902b3879/docs/modules/edge/eventbus.md (about)

     1  # EventBus
     2  ## Overview
     3  Eventbus acts as an interface for sending/receiving messages on mqtt topics.
     4  
     5  It supports 3 kinds of mode:
     6  - internalMqttMode
     7  - externalMqttMode 
     8  - bothMqttMode
     9  ## Topic
    10  eventbus subscribes to the following topics:
    11  ```
    12  - $hw/events/upload/#
    13  - SYS/dis/upload_records
    14  - SYS/dis/upload_records/+
    15  - $hw/event/node/+/membership/get
    16  - $hw/event/node/+/membership/get/+
    17  - $hw/events/device/+/state/update
    18  - $hw/events/device/+/state/update/+
    19  - $hw/event/device/+/twin/+
    20  ```
    21  Note: topic wildcards
    22  
    23  | wildcard  |  Description |
    24  |---|---|
    25  | #  |  It must be the last character in the topic, and matches the current tree and all subtrees. |
    26  | +  |  It matches exactly one item in the topic tree. |
    27  
    28  
    29  ## Flow chart
    30  ### **1. eventbus sends messages from external client**
    31  ![eventbus sends messages from external client](../../images/eventbus/eventbus-handleMsgFromClient.jpg)
    32  
    33  ### **2. eventbus sends response messages to external client**
    34  
    35  ![eventbus sends response messages to external client](../../images/eventbus/eventbus-handleResMsgToClient.jpg)
    36