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.
- Attributes:
  - type: Input message type (eg. ignition.msgs.Boolean)
  - topic: Input message topic name
<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:
  - type: Output message type (eg. ignition.msgs.Boolean)
  - topic: Output message topic name
- 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:

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>
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>
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]	_entity	The entity this plugin is attached to.
[in]	_sdf	The SDF Element associated with this system plugin.
[in]	_ecm	The EntityComponentManager of the given simulation instance.
[in]	_eventMgr	The 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.