Gazebo Gazebo

API Reference

3.15.1
TriggeredPublisher Class Reference

The triggered publisher system publishes a user specified message on an output topic in response to an input message that matches user specified criteria. More...

#include <TriggeredPublisher.hh>

Public Member Functions

 TriggeredPublisher ()=default
 Constructor. More...
 
 ~TriggeredPublisher () override
 Destructor. More...
 
void Configure (const Entity &_entity, const std::shared_ptr< const sdf::Element > &_sdf, EntityComponentManager &_ecm, EventManager &_eventMgr) override
 Configure the system. More...
 
void DoWork ()
 Thread that handles publishing output messages. More...
 
bool MatchInput (const transport::ProtoMsg &_inputMsg)
 Helper function that calls Match on every InputMatcher available. More...
 
- Public Member Functions inherited from System
 System ()
 Constructor. More...
 
virtual ~System ()
 Destructor. More...
 

Detailed Description

The triggered publisher system publishes a user specified message on an output topic in response to an input message that matches user specified criteria.

System Parameters

  • <input> The tag contains the input message type, topic and matcher information.
  • <input><match>: Contains configuration for matchers. Multiple <match> tags are possible. An output message is triggered if all Matchers match.
    • Attributes:
      • logic_type("positive" or "negative"): Specifies whether a comparison must succeed or fail in order to trigger an output message. A "positive" value triggers a match when a comparison succeeds. A "negative" value triggers a match when a comparson fails. The default value is "positive"
      • tol: Tolerance for floating point comparisons.
      • field: If specified, only this field inside the input message is compared for a match.
    • Value: String used to construct the protobuf message against which input messages are matched. This is the human-readable representation of a protobuf message as used by ign topic for publishing messages
  • <output>: Contains configuration for output messages: Multiple <output> tags are possible. A message will be published on each output topic for each input that matches.
    • Attributes:
    • Value: String used to construct the output protobuf message . This is the human-readable representation of a protobuf message as used by ign topic for publishing messages

Examples:

  1. Any receipt of a Boolean messages on the input topic triggers an output
    <plugin>
    <input type="ignition.msgs.Boolean" topic="/input_topic"/>
    <output type="ignition.msgs.Empty" topic="/output_topic"/>
    </plugin>
  2. Full match: An output is triggered when a Boolean message with a value of "true" is received
    <plugin>
    <input type="ignition.msgs.Boolean" topic="/input_topic">
    <match>
    data: true
    </match>
    </input>
    <output type="ignition.msgs.Empty" topic="/output_topic"/>
    </plugin>
  3. Field match: An output is triggered when a specific field matches
    <plugin>
    <input type="ignition.msgs.Vector2d" topic="/input_topic">
    <match field="x">1.0</match>
    <match field="y">2.0</match>
    </input>
    <output type="ignition.msgs.Empty" topic="/output_topic"/>
    </plugin>

The logic_type attribute can be used to negate a match. That is, to trigger an output when the input does not equal the value in <match> For example, the following will trigger an ouput when the input does not equal 1 AND does not equal 2.

<plugin>
<input type="ignition.msgs.Int32" topic="/input_topic">
<match logic_type="negative">1</match>
<match logic_type="negative">2</match>
</input>
<output type="ignition.msgs.Empty" topic="/output_topic"/>
</plugin>

Repeated Fields

When a field matcher is used with repeated fields, the content of the repeated field is treated as a set and the comparison operator is set containment. For example, the data field of ignition.msgs.Int32_V is a repeated Int32 message. To match an input that contains the values 1 and 2 the following matcher can be used:

<plugin>
<input type="ignition.msgs.Int32_V" topic="/input_topic">
<match field="data">1</match>
<match field="data">2</match>
</input>
<output type="ignition.msgs.Empty" topic="/output_topic"/>
</plugin>

To match an Int32_V message with the exact contents {1, 2}, the full matcher is used instead

<plugin>
<input type="ignition.msgs.Int32_V" topic="/input_topic">
<match>
data: 1
data: 2
</match>
</input>
<output type="ignition.msgs.Empty" topic="/output_topic"/>
</plugin>

Limitations

The current implementation of this system does not support specifying a subfield of a repeated field in the "field" attribute. i.e, if field="f1.f2", f1 cannot be a repeated field.

Constructor & Destructor Documentation

◆ TriggeredPublisher()

TriggeredPublisher ( )
default

Constructor.

◆ ~TriggeredPublisher()

~TriggeredPublisher ( )
override

Destructor.

Member Function Documentation

◆ Configure()

void Configure ( const Entity _entity,
const std::shared_ptr< const sdf::Element > &  _sdf,
EntityComponentManager _ecm,
EventManager _eventMgr 
)
overridevirtual

Configure the system.

Parameters
[in]_entityThe entity this plugin is attached to.
[in]_sdfThe SDF Element associated with this system plugin.
[in]_ecmThe EntityComponentManager of the given simulation instance.
[in]_eventMgrThe EventManager of the given simulation instance.

Implements ISystemConfigure.

◆ DoWork()

void DoWork ( )

Thread that handles publishing output messages.

◆ MatchInput()

bool MatchInput ( const transport::ProtoMsg _inputMsg)

Helper function that calls Match on every InputMatcher available.

Parameters
[in]_inputMsgInput message
Returns
True if all of the matchers return true

The documentation for this class was generated from the following file: