aimrt.channel

Configuration Overview

The aimrt.channel configuration item is used to configure the Channel feature. Detailed configuration items are described below:

Node	Type	Optional	Default	Purpose
backends	array	Optional	[]	List of Channel backends
backends[i].type	string	Required	“”	Type of the Channel backend
backends[i].options	map	Optional	-	Configuration for the specific Channel backend
pub_topics_options	array	Optional	“”	Configuration for Channel Pub Topics
pub_topics_options[i].topic_name	string	Required	“”	Name of the Channel Pub Topic, supports regular expressions
pub_topics_options[i].enable_backends	string array	Required	[]	List of allowed Channel backends for the Channel Pub Topic
pub_topics_options[i].enable_filters	string array	Optional	[]	List of framework-side filters to be loaded for the Channel Pub Topic
sub_topics_options	array	Optional	“”	Configuration for Channel Sub Topics
sub_topics_options[i].topic_name	string	Required	“”	Name of the Channel Sub Topic, supports regular expressions
sub_topics_options[i].enable_backends	string array	Required	[]	List of allowed Channel backends for the Channel Sub Topic
sub_topics_options[i].enable_filters	string array	Optional	[]	List of framework-side filters to be loaded for the Channel Sub Topic

Detailed configuration instructions for aimrt.channel:

• backends is an array used to configure various Channel backends.

  • backends[i].type is the type of the Channel backend. AimRT officially provides the local backend, and some plugins also provide certain Channel backend types.

  • backends[i].options are the initialization parameters passed by AimRT to each Channel backend. The format of this configuration is defined by each Channel backend type; please refer to the documentation of the corresponding Channel backend type.

• pub_topics_options and sub_topics_options are rule lists used to control the Channel backend rules used by each Topic when publishing or subscribing to messages, where:

  • topic_name indicates the Topic name for this rule, configured as a regular expression. If the Topic name matches this regular expression, this rule will be applied.

  • enable_backends is a string array indicating that if the Topic name matches this rule, all messages published under this Topic will be delivered to all Channel backends in this list for processing. Note:

    • All names appearing in this array must have been configured in backends.

    • The order of Channel backends configured in this array determines the order in which messages are delivered to each Channel backend for processing.

  • enable_filters is a string array indicating the list of framework-side filters to be registered on the pub/sub side, with the order in the array being the order of filter registration. Some plugins provide framework-side filters for performing pre/post operations during channel invocation.

  • Rules are checked from top to bottom; once a Topic matches a rule, no further rules will be checked for that Topic.

In AimRT, the front-end interface and back-end implementation of the Channel are decoupled. After a message is Published through the interface, the actual publishing action is carried out by the Channel backend. Typically, after the Publish call, the message is sequentially delivered to various Channel backends for processing within the current thread. Most Channel backends handle messages asynchronously, but some special backends—such as the local backend—can be configured to invoke subscriber callbacks in a blocking manner. Therefore, how long the Publish method will block is undefined and depends on the specific backend configuration.

Here is a simple example:

aimrt:
  channel:
    backends:
      - type: local
      - type: mqtt
    pub_topics_options:
      - topic_name: "(.*)"
        enable_backends: [local]
        enable_filters: []
    sub_topics_options:
      - topic_name: "(.*)"
        enable_backends: [local]
        enable_filters: []

local Type Channel Backend

The local type Channel backend is an officially provided Channel backend by AimRT, used to publish messages to other modules within the same process. It automatically determines whether the publisher and subscriber are within the same Pkg and optimizes performance accordingly. All its configuration items are as follows:

Node	Type	Optional	Default	Purpose
subscriber_use_inline_executor	bool	Optional	true	Whether the subscriber callback uses the inline executor
subscriber_executor	string	Required when subscriber_use_inline_executor is false	“”	Name of the executor used for subscriber callbacks

Usage notes:

• If subscriber_use_inline_executor is set to true, the subscriber callback will be executed directly using the publisher’s executor, blocking the publisher’s Publish method until all subscriber callbacks have completed execution.

• subscriber_executor only takes effect when subscriber_use_inline_executor is false. The backend will deliver all subscriber callbacks to this executor for asynchronous execution, and the publisher’s Publish method will return immediately.

Here is a simple example:

aimrt:
  executor:
    executors:
      - name: work_thread_pool
        type: asio_thread
        options:
          thread_num: 4
  channel:
    backends:
      - type: local
        options:
          subscriber_use_inline_executor: false
          subscriber_executor: work_thread_pool
    pub_topics_options:
      - topic_name: "(.*)"
        enable_backends: [local]
    sub_topics_options:
      - topic_name: "(.*)"
        enable_backends: [local]