aimrt.channel

Configuration Overview

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

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

Detailed configuration description for aimrt.channel:

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

  • backends[i].type specifies the type of Channel backend. AimRT officially provides the local backend, while some plugins may offer additional Channel backend types.

  • backends[i].options contains initialization parameters passed by AimRT to each Channel backend. The configuration format is defined by each Channel backend type. Please refer to the corresponding Channel backend type documentation.

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

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

  • enable_backends is a string array indicating that if a 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 in this array determines the sequence in which messages are delivered to each Channel backend for processing.

  • enable_filters is a string array representing the list of framework-side pub/sub filters to be registered. The array order determines the registration sequence of filters. Some plugins provide framework-side filters for performing pre/post operations during channel calls.

  • Rules are checked from top to bottom. Once a Topic matches a rule, subsequent rules will not be checked for this Topic.

In AimRT, the Channel frontend interface and backend implementation are decoupled. After calling Publish in the interface, the actual publishing action is ultimately performed by the Channel backend. Messages are typically delivered sequentially to each Channel backend for processing in the current thread after calling Publish. Most Channel backends process messages asynchronously, but some special backends—such as the local backend—can be configured to block and call subscriber callbacks synchronously. Therefore, how long the Publish method blocks 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 official Channel backend provided by AimRT, used to publish messages to other modules within the same process. It automatically determines whether the publisher and subscriber are in the same Pkg and optimizes performance accordingly. All its configuration items are as follows:

Node	Type	Optional	Default Value	Purpose
subscriber_use_inline_executor	bool	Optional	true	Whether to use inline executor for subscriber callbacks
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 publisher’s executor is used directly to execute subscriber callbacks, which will block the Publish method until all subscriber callbacks are completed.

• subscriber_executor takes effect only when subscriber_use_inline_executor is false. The backend will asynchronously deliver subscriber callbacks to this executor, and the 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]