Skip to content

Latest commit

 

History

History
109 lines (74 loc) · 6.17 KB

echo_example.rst

File metadata and controls

109 lines (74 loc) · 6.17 KB
Raw

Echo Example

The following YAML configuration file configures a DDS Router to create a Simple Participant <user_manual_participants_simple> in Domain Id 0 and an Echo Participant <user_manual_participants_echo> that will print in stdout every message get in Domain 0, as well as information regarding discovery events.

../../resources/examples/echo.yaml

Configuration

Allowed Topics

This section lists the Topics <Topic> that the DDS Router will route from one Participant to the other. Topic HelloWorldTopic with datatype HelloWorld, and ROS 2 topic rt/chatter with datatype std_msgs::msg::dds_::String_ will be forwarded from SimpleParticipant to EchoParticipant, that will print the message in stdout.

../../resources/examples/echo.yaml

Simple Participant

This Participant is configured with a name, a kind and the Domain Id, which is 0 in this case.

../../resources/examples/echo.yaml

Echo Participant

This Participant is configured to display information regarding messages received, as well as discovery events. See Echo Participant Configuration <user_manual_participants_echo_configuration> for more details.

../../resources/examples/echo.yaml

Execute example

For a detailed explanation on how to execute the , refer to this section <user_manual_user_interface>.

Note

Internal entities for a specific topic are only created once a data receiver (Reader/Subscriber) is discovered. Hence, for these example to work, either substitute allowlist for builtin-topics <topic_filtering> in the configuration file, or launch a subscriber/listener in the same domain (0).

Execute with Fast DDS HelloWorld Example

Execute a Fast DDS HelloWorld example:

./DDSHelloWorldExample publisher

Execute with this configuration file (available in <path/to/ddsrouter_tool>/share/resources/configurations/examples/echo.yaml). The expected output from the DDS Router, printed by the Echo Participant is:

New endpoint discovered: Endpoint{01.0f.b8.d9.81.30.3d.a7.01.00.00.00|0.0.1.3;writer;DdsTopic{HelloWorldTopic;HelloWorld;Fuzzy{Level(20) TopicQoS{TRANSIENT_LOCAL;RELIABLE;SHARED;depth(5000)}}};SpecificEndpointQoS{Partitions{};OwnershipStrength{0}};Active;ParticipantId{SimpleParticipant}}.
In Endpoint: 01.0f.b8.d9.81.30.3d.a7.01.00.00.00|0.0.1.3 from Participant: ParticipantId{SimpleParticipant} in topic: DdsTopic{HelloWorldTopic;HelloWorld;Fuzzy{Level(20) TopicQoS{VOLATILE;BEST_EFFORT;SHARED;depth(5000)}}} payload received: Payload{00 01 00 00 01 00 00 00 0b 00 00 00 48 65 6c 6c 6f 57 6f 72 6c 64 00 00} with specific qos: SpecificEndpointQoS{Partitions{};OwnershipStrength{0}}.
In Endpoint: 01.0f.b8.d9.81.30.3d.a7.01.00.00.00|0.0.1.3 from Participant: ParticipantId{SimpleParticipant} in topic: DdsTopic{HelloWorldTopic;HelloWorld;Fuzzy{Level(20) TopicQoS{VOLATILE;BEST_EFFORT;SHARED;depth(5000)}}} payload received: Payload{00 01 00 00 02 00 00 00 0b 00 00 00 48 65 6c 6c 6f 57 6f 72 6c 64 00 00} with specific qos: SpecificEndpointQoS{Partitions{};OwnershipStrength{0}}.
...
In Endpoint: 01.0f.b8.d9.81.30.3d.a7.01.00.00.00|0.0.1.3 from Participant: ParticipantId{SimpleParticipant} in topic: DdsTopic{HelloWorldTopic;HelloWorld;Fuzzy{Level(20) TopicQoS{VOLATILE;BEST_EFFORT;SHARED;depth(5000)}}} payload received: Payload{00 01 00 00 0a 00 00 00 0b 00 00 00 48 65 6c 6c 6f 57 6f 72 6c 64 00 00} with specific qos: SpecificEndpointQoS{Partitions{};OwnershipStrength{0}}.

Execute with ROS 2 demo nodes

Execute a ROS 2 demo_nodes_cpp talker in default domain 0:

ros2 run demo_nodes_cpp talker

Execute with this configuration file (available in <path/to/ddsrouter_tool>/share/resources/configurations/examples/echo.yaml). The expected output from the DDS Router, printed by the Echo Participant is:

New endpoint discovered: Endpoint{01.0f.b8.d9.b6.3a.7d.95.01.00.00.00|0.0.1.3;writer;DdsTopic{ros_discovery_info;rmw_dds_common::msg::dds_::ParticipantEntitiesInfo_;Fuzzy{Level(20) TopicQoS{TRANSIENT_LOCAL;RELIABLE;SHARED;depth(5000)}}};SpecificEndpointQoS{Partitions{};OwnershipStrength{0}};Active;ParticipantId{SimpleParticipant}}.
New endpoint discovered: Endpoint{01.0f.b8.d9.b6.3a.7d.95.01.00.00.00|0.0.2.4;reader;DdsTopic{ros_discovery_info;rmw_dds_common::msg::dds_::ParticipantEntitiesInfo_;Fuzzy{Level(20) TopicQoS{TRANSIENT_LOCAL;RELIABLE;SHARED;depth(5000)}}};SpecificEndpointQoS{Partitions{};OwnershipStrength{0}};Active;ParticipantId{SimpleParticipant}}.
...
New endpoint discovered: Endpoint{01.0f.b8.d9.b6.3a.7d.95.01.00.00.00|0.0.12.3;writer;DdsTopic{rt/chatter;std_msgs::msg::dds_::String_;Fuzzy{Level(20) TopicQoS{VOLATILE;RELIABLE;SHARED;depth(5000)}}};SpecificEndpointQoS{Partitions{};OwnershipStrength{0}};Active;ParticipantId{SimpleParticipant}}.
In Endpoint: 01.0f.b8.d9.b6.3a.7d.95.01.00.00.00|0.0.12.3 from Participant: ParticipantId{SimpleParticipant} in topic: DdsTopic{rt/chatter;std_msgs::msg::dds_::String_;Fuzzy{Level(0) TopicQoS{VOLATILE;BEST_EFFORT;SHARED;depth(1000)}}} payload received: Payload{00 01 00 00 0f 00 00 00 48 65 6c 6c 6f 20 57 6f 72 6c 64 3a 20 31 00 00} with specific qos: SpecificEndpointQoS{Partitions{};OwnershipStrength{0}}.
In Endpoint: 01.0f.b8.d9.b6.3a.7d.95.01.00.00.00|0.0.12.3 from Participant: ParticipantId{SimpleParticipant} in topic: DdsTopic{rt/chatter;std_msgs::msg::dds_::String_;Fuzzy{Level(0) TopicQoS{VOLATILE;BEST_EFFORT;SHARED;depth(1000)}}} payload received: Payload{00 01 00 00 0f 00 00 00 48 65 6c 6c 6f 20 57 6f 72 6c 64 3a 20 32 00 00} with specific qos: SpecificEndpointQoS{Partitions{};OwnershipStrength{0}}.
...