eProsima Fast DDS Spy Documentation

eProsima

eProsima Fast DDS Spy is CLI interactive tool that allows to introspect a DDS network in human readable format. It is possible to query the network about the DomainParticipants connected, their endpoints (DataWriters and DataReaders) and the topics they communicate in. It is also possible to see the user data sent through network topics in a schematic format in run time.

Overview

eProsima Fast DDS Spy is a tool that introspect or “sniffing” DDS packages in the network and maintain a local database that is accessible from a interactive CLI. Fast DDS Spy responds to user commands introduced by text and print in stdin the information requested. This tool has several commands to interact with, that allows to get information regarding the status of the network. It supports to list topics existing, list Participants, DataReaders, DataWriters and even read user data in real time in a human readable format.

_images/overview.png

eProsima Fast DDS Spy is easily configurable and installed with a default setup, so that DDS topics, data types and entities are automatically discovered without the need to specify the types of data. This is because this tool exploits the DynamicTypes functionality of eProsima Fast DDS, the C++ implementation of the DDS (Data Distribution Service) Specification defined by the Object Management Group (OMG).

Contacts and Commercial support

Find more about us at eProsima’s webpage.

Support available at:

Contributing to the documentation

Fast DDS Spy Documentation is an open source project, and as such all contributions, both in the form of feedback and content generation, are most welcomed. To make such contributions, please refer to the Contribution Guidelines hosted in our GitHub repository.

Structure of the documentation

This documentation is organized into the sections below.

eProsima Fast DDS Spy Documentation

eProsima

eProsima Fast DDS Spy is CLI interactive tool that allows to introspect a DDS network in human readable format. It is possible to query the network about the DomainParticipants connected, their endpoints (DataWriters and DataReaders) and the topics they communicate in. It is also possible to see the user data sent through network topics in a schematic format in run time.

Overview

eProsima Fast DDS Spy is a tool that introspect or “sniffing” DDS packages in the network and maintain a local database that is accessible from a interactive CLI. Fast DDS Spy responds to user commands introduced by text and print in stdin the information requested. This tool has several commands to interact with, that allows to get information regarding the status of the network. It supports to list topics existing, list Participants, DataReaders, DataWriters and even read user data in real time in a human readable format.

_images/overview.png

eProsima Fast DDS Spy is easily configurable and installed with a default setup, so that DDS topics, data types and entities are automatically discovered without the need to specify the types of data. This is because this tool exploits the DynamicTypes functionality of eProsima Fast DDS, the C++ implementation of the DDS (Data Distribution Service) Specification defined by the Object Management Group (OMG).

Contacts and Commercial support

Find more about us at eProsima’s webpage.

Support available at:

Contributing to the documentation

Fast DDS Spy Documentation is an open source project, and as such all contributions, both in the form of feedback and content generation, are most welcomed. To make such contributions, please refer to the Contribution Guidelines hosted in our GitHub repository.

Structure of the documentation

This documentation is organized into the sections below.

Fast DDS Spy on Windows

Warning

The current version of Fast DDS Spy does not have installers for Windows platforms. Please refer to the Windows installation from sources section to learn how to build Fast DDS Spy on Windows from sources.

Fast DDS Spy on Linux

Warning

The current version of Fast DDS Spy does not have installers for Linux platforms. Please refer to the Linux installation from sources section to learn how to build Fast DDS Spy on Linux from sources.

Example of usage

This example will serve as a hands-on tutorial, aimed at introducing some of the key concepts and features that eProsima Fast DDS Spy has to offer.

Prerequisites

It is required to have eProsima Fast DDS Spy previously installed using one of the following installation methods:

Additionally, ShapesDemo is required to publish and subscribe shapes of different colors and sizes. Install it by following any of the methods described in the given links:

Start ShapesDemo

Let us launch a ShapesDemo instance and start publishing in topics Square with default settings.

_images/shapesdemo_publisher.png

Spy configuration

eProsima Fast DDS Spy runs with default configuration settings.

Additionally, it is possible to change the default configuration parameters by means of a YAML configuration file.

Note

Please refer to Configuration for more information on how to configure a eProsima Fast DDS Spy.

Spy execution

Source the following file to setup the eProsima Fast DDS Spy environment:

source install/setup.bash

Launch an eProsima Fast DDS Spy instance as executing the following command:

fastddsspy

Try out all the commands DDS Spy has to offer:

  • participants

- name: Fast DDS ShapesDemo Participant
  guid: 01.0f.44.59.21.58.14.d2.00.00.00.00|0.0.1.c1
- name: Fast DDS ShapesDemo Participant
  guid: 01.0f.44.59.da.57.de.ec.00.00.00.00|0.0.1.c1
- ...
  • datawriters

- name: Fast DDS ShapesDemo Participant
  guid: 01.0f.44.59.21.58.14.d2.00.00.00.00|0.0.1.c1
- name: Fast DDS ShapesDemo Participant
  guid: 01.0f.44.59.da.57.de.ec.00.00.00.00|0.0.1.c1
- ...
  • topics

- name: Circle
  type: ShapeType
  datawriters: 2
  datareaders: 2
  rate: 13.0298 Hz
- name: Square
  type: ShapeType
  datawriters: 3
  datareaders: 2
  rate: 26.6975 Hz
  • topics Square

name: Circle
type: ShapeType
datawriters:
  - 01.0f.44.59.da.57.de.ec.00.00.00.00|0.0.6.2
datareaders:
  - 01.0f.44.59.c9.65.78.e5.00.00.00.00|0.0.2.7
rate: 13.0418 Hz
dynamic_type_discovered: true
  • help

Insert a command for Fast DDS Spy:
>> help
Fast DDS Spy is an interactive CLI that allow to instrospect DDS networks.
Each command shows data related with the network in Yaml format.
Commands available and the information they show:
    help                   : this help.
    version                : tool version.
    quit                   : exit interactive CLI and close program.
    participants           : DomainParticipants discovered in the network.
    participants verbose   : verbose information about DomainParticipants discovered in the network.
    participants <Guid>    : verbose information related with a specific DomainParticipant.
    writers                : DataWriters discovered in the network.
    writers verbose        : verbose information about DataWriters discovered in the network.
    writers <Guid>         : verbose information related with a specific DataWriter.
    reader                 : DataReaders discovered in the network.
    reader verbose         : verbose information about DataReaders discovered in the network.
    reader <Guid>          : verbose information related with a specific DataReader.
    topics                 : Topics discovered in the network.
    topics verbose         : verbose information about Topics discovered in the network.
    topics <name>          : verbose information related with a specific Topic.
    show <name>            : data of a specific Topic (Data Type must be discovered).
    show <name> verbose    : data with additional source info of a specific Topic.
    show all               : verbose data of all topics (only those whose Data Type is discovered).

Notes and comments:
    To exit from data printing, press enter.
    Each command is accessible by using its first letter (h/v/q/p/w/r/t/s).

For more information about these commands and formats, please refer to the documentation:
https://fast-dds-spy.readthedocs.io/en/latest/

Stop eProsima Fast DDS Spy typing exit.

Next Steps

Since the main steps for running Fast DDS Spy have already been explained, you can now continue by applying a configuration file to this tool to adjust it to your monitoring and debugging needs. These configurations include settings to enable or disable the DDS communication transports used by Fast DDS Spy, set the DDS Domain to monitor, or define lists of allowed and blocked topics, among others.

Please refer to the Configuration section of this documentation to know more about all settings available for the Fast DDS Spy.

User Interface

eProsima Fast DDS Spy is a CLI user application executed from command line and configured through a YAML configuration file.

Run application

Run eProsima Fast DDS Spy application by using command fastddsspy.

Source Dependency Libraries

eProsima Fast DDS Spy depends on some eProsima projects as Fast DDS or DDS Pipe. In order to correctly execute the application, make sure that these dependencies are properly sourced.

source <path-to-fastdds-installation>/install/setup.bash

Note

If Fast DDS has been installed in the system, these libraries would be sourced by default.

Application Arguments

The eProsima Fast DDS Spy application supports several input arguments:

Command

Option

Long option

Value

Default Value

Help Argument

-h

--help

Version Argument

-v

--version

Configuration File Argument

-c

--config-path

Readable File Path

./FASTDDSSPY_CONFIGURATION.yaml

Help Argument

It shows the usage information of the application.

Usage: Fast DDS Spy
Start an interactive CLI to introspect a DDS network.
General options:

Application help and information.
-h --help           Print this help message.
-v --version        Print version, branch and commit hash.

Application parameters
-c --config-path    Path to the Configuration File (yaml format) [Default: ./FASTDDSSPY_CONFIGURATION.yaml].

Version Argument

It shows the current version of the Fast DDS Spy and the hash of the last commit of the compiled code.

Configuration File Argument

A Fast DDS Spy supports YAML configuration file. Please refer to Configuration for more information on how to build this configuration file.

This YAML configuration can passed as argument to Fast DDS Spy when executed. If no configuration file is provided as argument, Fast DDS Spy will attempt to load a file named FASTDDSSPY_CONFIGURATION.yaml that must be in the same directory where the application is executed. If no configuration file is found, Fast DDS Spy will use default configuration.

Reload Topics

This configuration file allows to allow and block DDS Topics. A modification in this file will modify the running application.

Interactive application

The standard way to use this application is by running the interactive CLI. This is a user interface that repeatedly ask the user for a command, expecting a stdin command and arguments in order to retrieve the data querying the internal database.

Insert a command for Fast DDS Spy:
>>

Check the following section to see the available commands and their arguments, or use help command to get this information in stdout.

Close Application

Use Quit to stop and close the application.

One-shot application

eProsima Fast DDS Spy can be executed as a one-shot application. This is, an application that connects to a DDS network, queries a specific command to the internal database generated from such DDS network, and retrieves the information by stdout. Thus it will not ask the user for commands, neither wait before closing.

In order to execute Fast DDS Spy in one-shot mode add the command and arguments right after the last tool argument.

This kind of application depends on the network size and speed in order to discover every entity before showing the information and close. In order to configure the amount of time elapsed before querying for the information requested, use Discovery Time.

Note

Running a Fast DDS Spy instance will create DDS entities that will discover and connect everything in the same network. Thus, running one-shot Fast DDS Spy applications very frequently could affect to network performance, as each instance will be created and destroyed in the process.

Example

Let’s assume we want to retrieve the information of every DomainParticipant running in a current network.

Using the Interactive application, this will be the process and the output:

<path>$ fastddsspy

 ____|             |        __ \   __ \    ___|        ___|
|     _` |   __|  __|      |   |  |   | \___ \      \___ \   __ \   |   |
__|  (   | \__ \  |        |   |  |   |       |           |  |   |  |   |
_|   \__,_| ____/ \__|     ____/  ____/  _____/      _____/   .__/  \__, |
                                                            _|     ____/


Insert a command for Fast DDS Spy:
>> participants
- name: Fast DDS ShapesDemo Participant
  guid: 01.0f.44.59.21.58.14.d2.00.00.00.00|0.0.1.c1

Insert a command for Fast DDS Spy:
>> quit
<path>$

However, using One-shot application this will be expected result:

<path>$ fastddsspy participants
- name: Fast DDS ShapesDemo Participant
  guid: 01.0f.44.59.21.58.14.d2.00.00.00.00|0.0.1.c1
<path>$

Configuration

A Fast DDS Spy instance can be configured by a YAML configuration file. In order to retrieve a configuration file to a Fast DDS Spy, use Configuration File Argument.

DDS Configurations

The YAML Configuration supports a dds optional tag that contains certain DDS configurations. The values available to configure are:

Topic Filtering

The Fast DDS Spy automatically detects the topics that are being used in a DDS Network. The Fast DDS Spy then creates internal DDS Readers for each topic to process the data published. The Fast DDS Spy allows filtering DDS Topics, that is, it allows users to configure the DDS Topics to process. These data filtering rules can be configured under the allowlist and blocklist tags. If the allowlist and blocklist are not configured, the Fast DDS Spy will process all the data published on the topics it discovers. If both the allowlist and blocklist are configured and a topic appears in both of them, the blocklist has priority and the topic will be blocked.

Topics are determined by the tags name (required) and type, both of which accept wildcard characters.

Note

Placing quotation marks around values in a YAML file is generally optional, but values containing wildcard characters do require single or double quotation marks.

Consider the following example:

allowlist:
  - name: AllowedTopic1
    type: Allowed

  - name: AllowedTopic2
    type: "*"

  - name: HelloWorldTopic
    type: HelloWorld

blocklist:
  - name: "*"
    type: HelloWorld

In this example, the data in the topic AllowedTopic1 with type Allowed and the data in the topic AllowedTopic2 with any type will be processed by the Fast DDS Spy. The data in the topic HelloWorldTopic with type HelloWorld will be blocked, since the blocklist is blocking all topics with any name and with type HelloWorld.

Topic QoS

The following is the set of QoS that are configurable for a topic. For more information on topics, please read the Fast DDS Topic section.

Quality of Service

Yaml tag

Data type

Default value

QoS set

Reliability

reliability

bool

false

RELIABLE / BEST_EFFORT

Durability

durability

bool

false

TRANSIENT_LOCAL / VOLATILE

Ownership

ownership

bool

false

EXCLUSIVE_OWNERSHIP_QOS / SHARED_OWNERSHIP_QOS

Partitions

partitions

bool

false

Topic with / without partitions

Key

keyed

bool

false

Topic with / without key

History Depth

history-depth

unsigned integer

5000

History Depth

Max Reception Rate

max-rx-rate

float

0 (unlimited)

Max Reception Rate

Downsampling

downsampling

unsigned integer

1

Downsampling

Warning

Manually configuring TRANSIENT_LOCAL durability may lead to incompatibility issues when the discovered reliability is BEST_EFFORT. Please ensure to always configure the reliability when configuring the durability to avoid the issue.

History Depth

The history-depth tag configures the history depth of the Fast DDS internal entities. By default, the depth of every RTPS History instance is 5000. Its value should be decreased when the sample size and/or number of created endpoints (increasing with the number of topics) are big enough to cause memory exhaustion issues.

Max Reception Rate

The max-rx-rate tag limits the frequency [Hz] at which samples are processed by discarding messages received before 1/max-rx-rate seconds have passed since the last processed message. It only accepts non-negative numbers. By default it is set to 0; it processes samples at an unlimited reception rate.

Downsampling

The downsampling tag reduces the sampling rate of the received data by only keeping 1 out of every n samples received (per topic), where n is the value specified under the downsampling tag. When the max-rx-rate tag is also set, downsampling only applies to messages that have passed the max-rx-rate filter. It only accepts positive integers. By default it is set to 1; it accepts every message.

Manual Topics

A subset of Topic QoS can be manually configured for a specific topic under the tag topics. The tag topics has a required name tag that accepts wildcard characters. It also has two optional tags: a type tag that accepts wildcard characters and a qos tag with the Topic QoS that the user wants to manually configure. If a qos is not manually configured, it will get its value by discovery.

topics:
  - name: "temperature/*"
    type: "temperature/types/*"
    qos:
      max-tx-rate: 15
      downsampling: 2

Note

The Topic QoS configured in the Manual Topics take precedence over the Specs Topic QoS.

DDS Domain Id

In order to execute a Fast DDS Spy instance in a Domain Id different than the default (0) use tag domain.

Ignore Participant Flags

A set of discovery traffic filters can be defined in order to add an extra level of isolation. This configuration option can be set through the ignore-participant-flags tag:

ignore-participant-flags: no_filter                          # No filter (default)
# or
ignore-participant-flags: filter_different_host              # Discovery traffic from another host is discarded
# or
ignore-participant-flags: filter_different_process           # Discovery traffic from another process on same host is discarded
# or
ignore-participant-flags: filter_same_process                # Discovery traffic from own process is discarded
# or
ignore-participant-flags: filter_different_and_same_process  # Discovery traffic from own host is discarded

See Ignore Participant Flags for more information.

Custom Transport Descriptors

By default, Fast DDS Spy internal participants are created with enabled UDP and Shared Memory transport descriptors. The use of one or the other for communication will depend on the specific scenario, and whenever both are viable candidates, the most efficient one (Shared Memory Transport) is automatically selected. However, a user may desire to force the use of one of the two, which can be accomplished via the transport configuration tag.

transport: builtin    # UDP & SHM (default)
# or
transport: udp        # UDP only
# or
transport: shm        # SHM only

Warning

When configured with transport: shm, Fast DDS Spy will only communicate with applications using Shared Memory Transport exclusively (with disabled UDP transport).

Interface Whitelist

Optional tag whitelist-interfaces allows to limit the network interfaces used by UDP and TCP transport. This may be useful to only allow communication within the host (note: same can be done with Ignore Participant Flags). Example:

whitelist-interfaces:
  - "127.0.0.1"    # Localhost only

See Interface Whitelist for more information.

Topic type format

The optional ros2-types tag enables specification of the format for displaying schemas. When set to true, schemas are displayed in ROS 2 message format (.msg). If set to false, schemas are displayed in OMG IDL format (.idl).

Specs Configurations

The YAML Configuration supports a specs optional tag that contains certain options related with the overall configuration of the application. The values available to configure are:

Number of Threads

specs supports a threads optional value that allows the user to set a maximum number of threads for the internal ThreadPool. This ThreadPool allows to limit the number of threads spawned by the application. This improves the performance of the data transmission between participants.

This value should be set by each user depending on each system characteristics. By default, this value is 12.

Discovery Time

specs supports a discovery-time optional value that allows the user to set the time (in milliseconds) before a One-shot application retrieves the output and closes. This parameter is useful for very big networks, as Fast DDS Spy may not discover the whole network fast enough to return a complete information. By default, this value is 1000 (1 second).

QoS

specs supports a qos optional tag to configure the default values of the Topic QoS.

Note

The Topic QoS configured in specs can be overwritten by the Manual Topics.

Default Configuration

This is a YAML file that uses all supported configurations and set them as default:

Warning

This example can be used as a quick reference, but it may not be correct due to incompatibility or exclusive properties. Do not take it as a working example.

dds:
  domain: 0

  allowlist:
    - name: "topic_name"
      type: "topic_type"

  blocklist:
    - name: "topic_name"
      type: "topic_type"

  topics:
    - name: "temperature/*"
      type: "temperature/types/*"
      qos:
        max-rx-rate: 5
        downsampling: 1

  ignore-participant-flags: no_filter
  transport: builtin
  whitelist-interfaces:
    - "127.0.0.1"

  ros2-types: false

specs:
  threads: 12
  discovery-time: 1000

  qos:
    history-depth: 5000
    max-rx-rate: 10
    downsampling: 2

Commands

These are the commands supported so far by Fast DDS Spy. Every command explained in this section is available from the Interactive application and from the One-shot application. Most of the commands and arguments available have shortcuts and other names related. Thus, multiple words execute the same commands (e.g. participant = participants = p).

Entity Commands

The information retrieved by these commands follows YAML format and queries the application database about the network current status.

Participants

Participants is a command that retrieves information of the DomainParticipants currently active in the network.

Key-words

These are the key-words recognize as this command: participant participants p P.

Arguments

Participants command support 0 or 1 argument:

No argument

When no arguments are given to this command, the information shown is a list with every participant currently active in the network, giving their Guid and names. The output format is as follows: Simple Participant info.

Verbose

This argument queries for more complete information about each of the DomainParticipants in the network. It adds the information about endpoints and the topics they communicate in of each of the participants. The output got is a list of data with verbose information. Check the verbose section in order to know which key-words are available for this argument.

Guid

This argument requires a string with Guid format. This command queries the database for a single DomainParticipant and retrieves its verbose information. This Guid must exist inside the DDS network.

Note

If you are using eProsima Fast DDS Spy as one-shot application, you will need to put GUID in quotes.

Output Format

The participant information is retrieved in 2 formats depending on the verbose option.

Simple Participant info
name: <participant name>
guid: <guid>
Verbose Participant info
name: <participant name>
guid: <guid>
datawriters:
    - <topic name> [<topic data type name>] (<number of datawriters>)
    - ...
datareaders:
    - <topic name> [<topic data type name>] (<number of datareaders>)
    - ...
Example

Let’s assume we have a DDS network where 2 ShapesDemo applications are running.

This would be the expected output for the command participants:

- name: Fast DDS ShapesDemo Participant
  guid: 01.0f.44.59.21.58.14.d2.00.00.00.00|0.0.1.c1
- name: Fast DDS ShapesDemo Participant
  guid: 01.0f.44.59.da.57.de.ec.00.00.00.00|0.0.1.c1
- ...

This would be the expected output for the command participants verbose:

- name: Fast DDS ShapesDemo Participant
  guid: 01.0f.44.59.21.58.14.d2.00.00.00.00|0.0.1.c1
  datawriters:
    - Triangle [ShapeType] (1)
  datareaders:
    - Square [ShapeType] (1)
- name: Fast DDS ShapesDemo Participant
  guid: 01.0f.44.59.da.57.de.ec.00.00.00.00|0.0.1.c1
  datawriters:
    - Square [ShapeType] (2)
    - Circle [ShapeType] (1)
- ...

This would be the expected output for the command participants 01.0f.44.59.da.57.de.ec.00.00.00.00|0.0.1.c1:

name: Fast DDS ShapesDemo Participant
guid: 01.0f.44.59.da.57.de.ec.00.00.00.00|0.0.1.c1
datawriters:
  - Square [ShapeType] (2)
  - Circle [ShapeType] (1)

Writers

Writers is a command that retrieves information of the DataWriters currently active in the network.

Key-words

These are the key-words recognize as this command: writer writers datawriter datawriters publication publications w W.

Arguments

Writers command support 0 or 1 argument:

No argument

When no arguments are given to this command, the information shown is a list with every DataWriter currently active in the network, giving their :term:<Guid>, the name of their respective DomainParticipants, and the topic name and topic data type name. The output format is as follows: Simple Writer info.

Verbose

This argument queries for more complete information about each of the DataWriters in the network. It adds information about the QoS. The output got is a list of DataWriters with verbose information. Check the verbose section in order to know which key-words are available for this argument.

Guid

This argument requires a string with Guid format. This command queries the database for a single DataWriter and retrieves its verbose information. This Guid must exist inside the DDS network.

Note

If you are using eProsima Fast DDS Spy as one-shot application, you will need to put GUID in quotes.

Output Format

The writer information is retrieved in 2 formats depending on the verbose option.

Simple Writer info
guid: <guid>
name: <participant name>
topic: <topic name> [<topic data type name>]
Verbose Writer info
name: <writer name>
guid: <guid>
topic:
    - <topic name>
    - <topic data type name>
qos:
    - durability: <volatile | transient-local>
    - reliability: <reliable | best-effort>
Example

Let’s assume we have a DDS network where 2 ShapesDemo applications are running.

This would be the expected output for the command writers:

- guid: 01.0f.44.59.21.58.14.d2.00.00.00.00|0.0.1.2
  participant: Fast DDS ShapesDemo Participant
  topic: Triangle [ShapeType]
- guid: 01.0f.44.59.da.57.de.ec.00.00.00.00|0.0.6.2
  participant: Fast DDS ShapesDemo Participant
  topic: Circle [ShapeType]
- ...

This would be the expected output for the command writers verbose:

- guid: 01.0f.44.59.21.58.14.d2.00.00.00.00|0.0.1.2
  participant: Fast DDS ShapesDemo Participant
  topic:
    name: Triangle
    type: ShapeType
  qos:
    durability: volatile
    reliability: best-effort
- guid: 01.0f.44.59.da.57.de.ec.00.00.00.00|0.0.6.2
  participant: Fast DDS ShapesDemo Participant
  topic:
    name: Circle
    type: ShapeType
  qos:
    durability: transient-local
    reliability: reliable
- ...

This would be the expected output for the command writers 01.0f.44.59.da.57.de.ec.00.00.00.00|0.0.6.2:

guid: 01.0f.44.59.da.57.de.ec.00.00.00.00|0.0.6.2
participant: Fast DDS ShapesDemo Participant
topic:
  name: Circle
  type: ShapeType
qos:
  durability: transient-local
  reliability: reliable

Readers

Readers is a command that retrieves information of the DataReaders currently active in the network.

Key-words

These are the key-words recognize as this command: reader readers datareader datareaders subscription subscriptions r R.

Arguments

Readers command support 0 or 1 argument:

No argument

When no arguments are given to this command, the information shown is a list with every DataReader currently active in the network, giving their Guid, the name of their respective DomainParticipants, and the topic name and topic data type name. The output format is as follows: Simple Reader info.

Verbose

This argument queries for more complete information about each of the DataReaders in the network. It adds information about the QoS. The output got is a list of DataReaders with verbose information. Check the verbose section in order to know which key-words are available for this argument.

Guid

This argument requires a string with Guid format. This command queries the database for a single DataReader and retrieves its verbose information. This Guid must exist inside the DDS network.

Note

If you are using eProsima Fast DDS Spy as one-shot application, you will need to put GUID in quotes.

Output Format

The reader information is retrieved in 2 formats depending on the verbose option.

Simple Reader info
guid: <guid>
name: <participant name>
topic: <topic name> [<topic data type name>]
Verbose Reader info
name: <reader name>
guid: <guid>
topic:
    - <topic name>
    - <topic data type name>
qos:
    - durability: <volatile | transient-local>
    - reliability: <reliable | best-effort>
Example

Let’s assume we have a DDS network where 2 ShapesDemo applications are running.

This would be the expected output for the command readers:

- guid: 01.0f.44.59.21.58.14.d2.00.00.00.00|0.0.1.2
  participant: Fast DDS ShapesDemo Participant
  topic: Triangle [ShapeType]
- guid: 01.0f.44.59.da.57.de.ec.00.00.00.00|0.0.6.2
  participant: Fast DDS ShapesDemo Participant
  topic: Circle [ShapeType]
- ...

This would be the expected output for the command readers verbose:

- guid: 01.0f.44.59.21.58.14.d2.00.00.00.00|0.0.1.2
  participant: Fast DDS ShapesDemo Participant
  topic:
    name: Triangle
    type: ShapeType
  qos:
    durability: volatile
    reliability: best-effort
- guid: 01.0f.44.59.da.57.de.ec.00.00.00.00|0.0.6.2
  participant: Fast DDS ShapesDemo Participant
  topic:
    name: Circle
    type: ShapeType
  qos:
    durability: transient-local
    reliability: reliable
- ...

This would be the expected output for the command readers 01.0f.44.59.da.57.de.ec.00.00.00.00|0.0.6.2:

guid: 01.0f.44.59.da.57.de.ec.00.00.00.00|0.0.6.2
participant: Fast DDS ShapesDemo Participant
topic:
  name: Circle
  type: ShapeType
qos:
  durability: transient-local
  reliability: reliable

Topic

Topic is a command that retrieves information of the Topics with at least one endpoint currently active in the network.

Key-words

These are the key-words recognize as this command: topic topics t T.

Arguments

Topic command support 0 or 1 argument:

No argument

When no arguments are given to this command, the information shown is a list with every topic with at least one endpoint currently active in the network. The information shown is the topic name, data type name, number of writers and readers and the subscription rate measured in samples per second. The output format is as follows: Simple Writer info.

Verbose

This argument queries for more complete information about each of the topics in the network. It adds the Guid of each endpoint on the topic and the whether the type has been discovered. The output is a list of data with verbose information. Check the verbose section in order to know which key-words are available for this argument.

Topic name

This argument requires a string with the topic name. This command queries the database for a single Topic and retrieves its verbose information. This Guid must exist inside the DDS network.

Note

If there are 2 topics with the same name and different Topic Data Type, only one of them could be visible. These is a circumstance that DDS allows, but it is strongly suggested not to do.

Output Format

The topic information is retrieved in 2 formats depending on the verbose option.

Simple Writer info
name: <topic name>
type: <data type name>
datawriters: <number of datawriters currently active>
datareaders: <number of datareaders currently active>
rate: <samples per second> Hz
Verbose Writer info
name: <topic name>
type: <data type name>
datawriters:
    - <Guid>
    - ...
datareaders:
    - <Guid>
    - ...
rate: <samples per second> Hz
dynamic_type_discovered: <bool>
Example

Let’s assume we have a DDS network where 2 ShapesDemo applications are running.

This would be the expected output for the command topics:

- name: Circle
  type: ShapeType
  datawriters: 2
  datareaders: 2
  rate: 13.0298 Hz
- name: Square
  type: ShapeType
  datawriters: 3
  datareaders: 2
  rate: 26.6975 Hz

This would be the expected output for the command topics verbose:

- name: Circle
  type: ShapeType
  datawriters:
    - 01.0f.44.59.da.57.de.ec.00.00.00.00|0.0.3.2
  datareaders:
    - 01.0f.44.59.c9.65.78.e5.00.00.00.00|0.0.2.7
  rate: 13.0286 Hz
  dynamic_type_discovered: true
- name: Square
  type: ShapeType
  datawriters:
    - 01.0f.44.59.da.57.de.ec.00.00.00.00|0.0.1.2
    - 01.0f.44.59.da.57.de.ec.00.00.00.00|0.0.2.2
  datareaders:
    - 01.0f.44.59.21.58.14.d2.00.00.00.00|0.0.2.7
    - 01.0f.44.59.da.57.de.ec.00.00.00.00|0.0.4.7
  rate: 26.685 Hz
  dynamic_type_discovered: true

This would be the expected output for the command topics Square:

name: Circle
type: ShapeType
datawriters:
  - 01.0f.44.59.da.57.de.ec.00.00.00.00|0.0.6.2
datareaders:
  - 01.0f.44.59.c9.65.78.e5.00.00.00.00|0.0.2.7
rate: 13.0418 Hz
dynamic_type_discovered: true

Data commands

This commands show user data being received by the application in real time.

Show

This command prints every User Data received in a human readable way. The information shown with this command is real-time data that is being received by Fast DDS Spy. In order to stop the command, press enter and the CLI will finish showing the data received.

Note

This is a real-time command that will not stop until enter is pressed.

Key-words

These are the key-words recognize as this command: show print s S.

Data Type discovered

In order for a Topic to be printable by the application, the Fast DDS Spy requires to know the data type of such topic. The information whether the topic data type is already discovered be the application can be shown by using Topic command.

Arguments

Show command support different combination of arguments:

Topic name

When a topic name is given, the information shown is the data received in real-time in the topic specified. The output format is as follows: Simple Data format.

Topic name + Verbose

Giving a topic name and the the verbose argument the output is the data received in real-time with additional meta-information as the topic name, the source timestamp, and the source DataWriter Guid. Data is printing using Verbose Data format.

All

This argument prints all topics which Data Type has been discovered. Data is printing using Verbose Data format.

Output Format

Note

The format of the data printed is not YAML. The correct YAML format will come in future releases.

The data information is retrieved in 2 formats depending on the verbose option.

Simple Data format

Only shows the data, by

---
<field name>: <value>
...
---
Verbose Data format
topic: <topic name> [<topic data type name>]
data: <Guid>
timestamp: <YYYY/MM/DD hh:mm:ss>
data:
---
<field name>: <value>
...
---
Example

Let’s assume we have a DDS network where 2 ShapesDemo applications are running.

This would be the expected output for the command show Circle:

---
color: GREEN
x: 168
y: 125
shapesize: 30
---

---
color: GREEN
x: 173
y: 121
shapesize: 30
---

...

This would be the expected output for the command show Circle verbose:

topic: Circle [ShapeType]
data: 01.0f.44.59.da.57.de.ec.00.00.00.00|0.0.6.2
timestamp: 2023/03/27 09:35:23
data:
---
color: GREEN
x: 72
y: 125
shapesize: 30
---

topic: Circle [ShapeType]
data: 01.0f.44.59.da.57.de.ec.00.00.00.00|0.0.6.2
timestamp: 2023/03/27 09:35:24
data:
---
color: GREEN
x: 66
y: 120
shapesize: 30
---

...

This would be the expected output for the command datas 01.0f.22.ba.3b.47.ab.3c.00.00.00.00|0.0.1.c1:

topic: Square [ShapeType]
data: 01.0f.44.59.da.57.de.ec.00.00.00.00|0.0.2.2
timestamp: 2023/03/27 09:35:25
data:
---
color: BLUE
x: 158
y: 70
shapesize: 20
---

topic: Triangle [ShapeType]
data: 01.0f.44.59.21.58.14.d2.00.00.00.00|0.0.1.2
timestamp: 2023/03/27 09:35:26
data:
---
color: YELLOE
x: 93
y: 75
shapesize: 25
---

...

Extra commands

These are other commands available in the application.

Help

Show the help information with all the commands available by Fast DDS Spy.

Key-words

These are the key-words recognize as this command: h help H man.

Version

Show the version information and commit of the application running.

Key-words

These are the key-words recognize as this command: version v V.

Quit

Stop and close the application.

Key-words

These are the key-words recognize as this command: q x quit quit() exit exit().

Input format

Input format for the application command arguments.

Verbose

verbose is a common argument for most of the Commands available. This argument generate more complete and complex output data for the query executed by the command. In order to see verbose information, add one of the key-words right after the command and its required arguments.

Key-words

These are the key-words recognize as this argument: verbose v -v --v V.

All

Some commands support an all argument.

Key-words

These are the key-words recognize as this argument: all a -a --a A.

Guid

Guid identifies a DDS entity by a unique Id.

Format

The format for the Guid is a string of 12 hexadecimal numbers separated by ., the Guid Prefix, followed by | and then 4 more hexadecimal values representing the Entity Id. e.g. 01.0f.22.ba.3b.47.ab.3c.00.00.00.00|00.00.01.c1.

Summary

Command

Description

Arguments

KeyWords

Participants

Show DomainParticipant info

_
verbose
<Guid>

participant participants
p P

Writers

Show DataWriter info

_
verbose
<Guid>

writer writers
datawriter datawriters
publication publications
w W

Readers

Show DataReader info

_
verbose
<Guid>

reader readers
datareader datareaders
subscription subscriptions
r R

Topic

Show Topic info

_
verbose
<topic name>

topic topics
t T

Show

Show real-time receiving user data.

<topic name>
<topic name> verbose
all

show print
s S

Help

Show help.

help man
h H

Version

Show version information.

version
v V

Quit

Stop and close application.

quit exit
quit() exit()
q Q x

Linux installation from sources

The instructions for installing the eProsima Fast DDS Spy from sources and its required dependencies are provided in this page. It is organized as follows:

Dependencies installation

Fast DDS Spy depends on eProsima Fast DDS library and certain Debian packages. This section describes the instructions for installing Fast DDS Spy dependencies and requirements in a Linux environment from sources. The following packages will be installed:

  • foonathan_memory_vendor, an STL compatible C++ memory allocation library.

  • fastcdr, a C++ library that serializes according to the standard CDR serialization mechanism.

  • fastrtps, the core library of eProsima Fast DDS library.

  • cmake_utils, an eProsima utils library for CMake.

  • cpp_utils, an eProsima utils library for C++.

  • ddspipe, an eProsima internal library that enables the communication of DDS interfaces.

First of all, the Requirements and Dependencies detailed below need to be met. Afterwards, the user can choose whether to follow either the colcon or the CMake installation instructions.

Requirements

The installation of eProsima Fast DDS Spy in a Linux environment from sources requires the following tools to be installed in the system:

CMake, g++, pip, wget and git

These packages provide the tools required to install eProsima Fast DDS Spy and its dependencies from command line. Install CMake, g++, pip, wget and git using the package manager of the appropriate Linux distribution. For example, on Ubuntu use the command:

sudo apt install cmake g++ pip wget git
Colcon

colcon is a command line tool based on CMake aimed at building sets of software packages. Install the ROS 2 development tools (colcon and vcstool) by executing the following command:

pip3 install -U colcon-common-extensions vcstool

Note

If this fails due to an Environment Error, add the --user flag to the pip3 installation command.

Gtest

Gtest is a unit testing library for C++. By default, eProsima Fast DDS Spy does not compile tests. It is possible to activate them with the opportune CMake options when calling colcon or CMake. For more details, please refer to the CMake options section. For a detailed description of the Gtest installation process, please refer to the Gtest Installation Guide.

It is also possible to clone the Gtest Github repository into the eProsima Fast DDS Spy workspace and compile it with colcon as a dependency package. Use the following command to download the code:

git clone --branch release-1.11.0 https://github.com/google/googletest src/googletest-distribution

Dependencies

eProsima Fast DDS Spy has the following dependencies, when installed from sources in a Linux environment:

Asio and TinyXML2 libraries

Asio is a cross-platform C++ library for network and low-level I/O programming, which provides a consistent asynchronous model. TinyXML2 is a simple, small and efficient C++ XML parser. Install these libraries using the package manager of the appropriate Linux distribution. For example, on Ubuntu use the command:

sudo apt install libasio-dev libtinyxml2-dev
OpenSSL

OpenSSL is a robust toolkit for the TLS and SSL protocols and a general-purpose cryptography library. Install OpenSSL using the package manager of the appropriate Linux distribution. For example, on Ubuntu use the command:

sudo apt install libssl-dev
yaml-cpp

yaml-cpp is a YAML parser and emitter in C++ matching the YAML 1.2 spec, and is used by Fast DDS Spy application to parse the provided configuration files. Install yaml-cpp using the package manager of the appropriate Linux distribution. For example, on Ubuntu use the command:

sudo apt install libyaml-cpp-dev
eProsima dependencies

If it already exists in the system an installation of Fast DDS and DDS Pipe libraries, just source this libraries when building eProsima Fast DDS Spy by running the following commands. In other case, just skip this step.

source <fastdds-installation-path>/install/setup.bash
source <ddspipe-installation-path>/install/setup.bash

Colcon installation

  1. Create a fastdds-spy directory and download the .repos file that will be used to install eProsima Fast DDS Spy and its dependencies:

    mkdir -p ~/fastdds-spy/src
    cd ~/fastdds-spy
    wget https://raw.githubusercontent.com/eProsima/Fast-DDS-Spy/v0.3.0/fastddsspy.repos
    vcs import src < fastddsspy.repos
    

    Note

    In case there is already a Fast DDS installation in the system it is not required to download and build every dependency in the .repos file. It is just needed to download and build the eProsima Fast DDS Spy project having sourced its dependencies. Refer to section eProsima dependencies in order to check how to source Fast DDS library.

  2. Build the packages:

    colcon build --packages-up-to-regex fastddsspy
    

Note

Being based on CMake, it is possible to pass the CMake configuration options to the colcon build command. For more information on the specific syntax, please refer to the CMake specific arguments page of the colcon manual.

CMake installation

There exist the possibility to install Fast DDS Spy by CMake, and could be see in following section. However Colcon installation is recommended.

Run an application

To run the Fast DDS Spy tool, source the installation path and execute the executable file that has been installed in <install-path>/fastddsspy_tool/bin/fastddsspy:

# If built has been done using colcon, all projects could be sourced as follows
source install/setup.bash
fastddsspy

Be sure that this executable has execution permissions.

Run tests

Windows installation from sources

The instructions for installing the eProsima Fast DDS Spy application from sources and its required dependencies are provided in this page. It is organized as follows:

Dependencies installation

eProsima Fast DDS Spy depends on eProsima Fast DDS library and certain Debian packages. This section describes the instructions for installing eProsima Fast DDS Spy dependencies and requirements in a Windows environment from sources. The following packages will be installed:

  • foonathan_memory_vendor, an STL compatible C++ memory allocation library.

  • fastcdr, a C++ library that serializes according to the standard CDR serialization mechanism.

  • fastrtps, the core library of eProsima Fast DDS library.

  • cmake_utils, an eProsima utils library for CMake.

  • cpp_utils, an eProsima utils library for C++.

  • ddspipe, an eProsima internal library that enables the communication of DDS interfaces.

First of all, the Requirements and Dependencies detailed below need to be met. Afterwards, the user can choose whether to follow either the colcon or the CMake installation instructions.

Requirements

The installation of eProsima Fast DDS in a Windows environment from sources requires the following tools to be installed in the system:

Visual Studio

Visual Studio is required to have a C++ compiler in the system. For this purpose, make sure to check the Desktop development with C++ option during the Visual Studio installation process.

If Visual Studio is already installed but the Visual C++ Redistributable packages are not, open Visual Studio and go to Tools -> Get Tools and Features and in the Workloads tab enable Desktop development with C++. Finally, click Modify at the bottom right.

Chocolatey

Chocolatey is a Windows package manager. It is needed to install some of eProsima Fast DDS’s dependencies. Download and install it directly from the website.

CMake, pip3, wget and git

These packages provide the tools required to install eProsima Fast DDS and its dependencies from command line. Download and install CMake, pip3, wget and git by following the instructions detailed in the respective websites. Once installed, add the path to the executables to the PATH from the Edit the system environment variables control panel.

Colcon

colcon is a command line tool based on CMake aimed at building sets of software packages. Install the ROS 2 development tools (colcon and vcstool) by executing the following command:

pip3 install -U colcon-common-extensions vcstool

Note

If this fails due to an Environment Error, add the --user flag to the pip3 installation command.

Gtest

Gtest is a unit testing library for C++. By default, eProsima Fast DDS Spy does not compile tests. It is possible to activate them with the opportune CMake options when calling colcon or CMake. For more details, please refer to the CMake options section.

Run the following commands on your workspace to install Gtest.

git clone https://github.com/google/googletest.git
cmake -DCMAKE_INSTALL_PREFIX='C:\Program Files\gtest' -Dgtest_force_shared_crt=ON -DBUILD_GMOCK=ON ^
    -B build\gtest -A x64 -T host=x64 googletest
cmake --build build\gtest --config Release --target install

or refer to the Gtest Installation Guide for a detailed description of the Gtest installation process.

Dependencies

eProsima Fast DDS Spy has the following dependencies, when installed from sources in a Windows environment:

Asio and TinyXML2 libraries

Asio is a cross-platform C++ library for network and low-level I/O programming, which provides a consistent asynchronous model. TinyXML2 is a simple, small and efficient C++ XML parser. They can be downloaded directly from the links below:

After downloading these packages, open an administrative shell with PowerShell and execute the following command:

choco install -y -s <PATH_TO_DOWNLOADS> asio tinyxml2

where <PATH_TO_DOWNLOADS> is the folder into which the packages have been downloaded.

OpenSSL

OpenSSL is a robust toolkit for the TLS and SSL protocols and a general-purpose cryptography library. Download and install the latest OpenSSL version for Windows at this link. After installing, add the environment variable OPENSSL_ROOT_DIR pointing to the installation root directory.

For example:

OPENSSL_ROOT_DIR=C:\Program Files\OpenSSL-Win64
yaml-cpp

yaml-cpp is a YAML parser and emitter in C++ matching the YAML 1.2 spec, and is used by Fast DDS Spy application to parse the provided configuration files. From an administrative shell with PowerShell, execute the following commands in order to download and install yaml-cpp for Windows:

git clone --branch yaml-cpp-0.7.0 https://github.com/jbeder/yaml-cpp
cmake -DCMAKE_INSTALL_PREFIX='C:\Program Files\yamlcpp' -B build\yamlcpp yaml-cpp
cmake --build build\yamlcpp --target install    # If building in Debug mode, add --config Debug
eProsima dependencies

If it already exists in the system an installation of Fast DDS and DDS Pipe libraries, just source this libraries when building the eProsima Fast DDS Spy application by using the command:

source <fastdds-installation-path>/install/setup.bash
source <ddspipe-installation-path>/install/setup.bash

In other case, just skip this step.

CMake installation

There exist the possibility to install Fast DDS Spy by CMake, and could be see in following section. However Colcon installation is recommended.

Run an application

If the eProsima Fast DDS Spy was compiled using colcon, when running an instance of a Fast DDS Spy, the colcon overlay built in the dedicated fastdds-spy directory must be sourced. There are two possibilities:

  • Every time a new shell is opened, prepare the environment locally by typing the command:

    setup.bat
    fastddsspy
    
  • Add the sourcing of the colcon overlay permanently, by opening the Edit the system environment variables control panel, and adding the installation path to the PATH.

However, when running an instance of a Fast DDS Spy compiled using CMake, it must be linked with its dependencies where the packages have been installed. This can be done by opening the Edit system environment variables control panel and adding to the PATH the eProsima Fast DDS Spy, Fast DDS, Fast CDR, DDS Pipe installation directories:

  • Fast DDS: C:\\Program Files\\fastrtps

  • Fast CDR: C:\\Program Files\\fastcdr

  • DDS Pipe: C:\\Program Files\\ddspipe

  • eProsima Fast DDS Spy: C:\\Program Files\\ddsrecord

CMake options

eProsima Fast DDS Spy provides numerous CMake options for changing the behavior and configuration of eProsima Fast DDS Spy. These options allow the developer to enable/disable certain eProsima Fast DDS Spy settings by defining these options to ON/OFF at the CMake execution, or set the required path to certain dependencies.

Warning

These options are only for developers who installed eProsima Fast DDS Spy following the compilation steps described in Linux installation from sources.

Option

Description

Possible values

Default

CMAKE_BUILD_TYPE

CMake optimization build type.

Release
Debug

Release

BUILD_DOCS

Build the eProsima Fast DDS Spy documentation.

OFF
ON

OFF

BUILD_TESTS

Build the eProsima Fast DDS Spy tools and documentation
tests.

OFF
ON

OFF

LOG_INFO

Activate eProsima Fast DDS Spy logs. It is
set to ON if CMAKE_BUILD_TYPE is set
to Debug.

OFF
ON

ON if Debug
OFF otherwise

ASAN_BUILD

Activate address sanitizer build.

OFF
ON

OFF

TSAN_BUILD

Activate thread sanitizer build.

OFF
ON

OFF

Version v0.3.0

This release includes the following Configuration Features:

  • Display data type information in either ROS 2 format (MSG) or DDS format (IDL).

  • Topic configuration.

  • Max Reception Rate per topic.

  • Downsampling per topic.

  • Remove the support for built-in Topics.

  • Set app_id and app_metadata attributes in eProsima Fast DDS Spy participants.

  • Make the trigger of the DDS Pipe callbacks configurable.

  • Support both fastcdr v1 and v2.

  • Add support for Fast DDS versions lower than v2.13.

This release includes the following Bugfixes: * Add participant and endpoint info topics to allowlist. * Add internal builtin topics as DDS Topics. * Reload internal topics when reloading the configuration file. * Process an empty YAML when a configuration file isn’t provided.

This release includes the following Documentation Updates: * Update next steps in main example and remove warning in docker installation. * Fix documentation build for Sphinx versions lower than 5.0.

This release includes the following Dependencies Update:

Repository

Old Version

New Version

Foonathan Memory Vendor

eProsima/foonathan_memory_vendor

v1.3.1

v1.3.1

Fast CDR

eProsima/Fast-CDR

v1.1.0

v2.1.3

Fast DDS

eProsima/Fast-DDS

v2.11.0

v2.13.1

Dev Utils

eProsima/dev-utils

v0.4.0

v0.5.0

DDS Pipe

eProsima/DDS-Pipe

v0.2.0

v0.3.0

Previous Versions

Version v0.2.0

This release includes the following Configuration Features:

This release includes the following Internal Changes and Bugfixes:

  • Print only active participants when using verbose mode in participants command.

  • Fix C++ namespace ambiguities in yaml configuration.

  • Change default log-filter to only show warning coming from DDS Spy source code.

  • Filter out topics associated to services (RPC).

  • Parameterize simulated endpoints.

This release includes the following Documentation Updates:

  • Update introduction section in README file.

This release includes the following change in the Continuous Integration process:

This release includes the following Dependencies Update:

Repository

Old Version

New Version

Foonathan Memory Vendor

eProsima/foonathan_memory_vendor

v1.3.0

v1.3.1

Fast CDR

eProsima/Fast-CDR

v1.0.27

v1.1.0

Fast DDS

eProsima/Fast-DDS

v2.10.1

v2.11.0

Dev Utils

eProsima/dev-utils

v0.3.0

v0.4.0

DDS Pipe

eProsima/DDS-Pipe

v0.1.0

v0.2.0

Version v0.1.0

This is the first release of eProsima Fast DDS Spy.

This release includes several features regarding the introspection of DDS data, configuration and user interaction.

This release includes the following User Interface features:

This release includes the following Configuration features:

This release includes the following Introspection features:

This release includes the following Documentation features:

  • This same documentation.

This release includes the following Installation features:

  • Dockerfile to build an image of the application Fast-DDS-Spy/docker.

Glossary

CLI

Command Line Interface This is a channel of communication between application and user using the Command Line, so-called Terminal.

DDS

Data Distribution Service protocol. Specification: https://www.omg.org/spec/DDS/.

YAML

YAML Ain’t Markup Language human-friendly data serialization language. Specification: https://yaml.org/.

DDS nomenclature

DataReader

DDS element that subscribes to a specific Topic. It belong to one and only one Participant, and it is uniquely identified by a Guid.

See Fast DDS documentation for further information.

DataWriter

DDS entity that publish data in a specific Topic. It belong to one and only one Participant, and it is uniquely identified by a Guid.

See Fast DDS documentation for further information.

Discovery Server

Discovery Server Discovery Protocol is a Fast DDS feature that enables a new Discovery mechanism based on a Server that filters and distribute the discovery information. This is highly recommended in networks where multicast is not available (e.g. WAN).

See Fast DDS documentation for further information.

Domain Id

The Domain Id is a virtual partition for DDS networks. Only DomainParticipants with the same Domain Id would be able to communicate to each other. DomainParticipants in different Domains will not even discover each other.

See Fast DDS documentation for further information.

DomainParticipant

A DomainParticipant is the entry point of the application to a DDS Domain. Every DomainParticipant is linked to a single domain from its creation, and cannot change such domain. It also acts as a factory for Publisher, Subscriber and Topic.

See Fast DDS documentation for further information.

Endpoint

DDS element that publish or subscribes in a specific Topic. Endpoint kinds are DataWriter or DataReader.

Entity Id

DDS Identifier created by 4 bytes, represented by 4 hexadecimal values separated by .. This identifier differentiates each of the entities inside a DomainParticipant. e.g. 00.00.01.c1.

Guid Prefix

DDS Identifier created by 12 bytes, represented by 12 hexadecimal values separated by .. Every entity that belongs to the same DomainParticipant has the same Guid Prefix. The EntityId uniquely identifies sub-entities inside a Participant. e.g. 01.0f.22.ba.3b.47.ab.3c.00.00.00.00.

Guid

Global Unique Identifier. It contains a Guid Prefix and an Entity Id. Identifies uniquely a DDS entity (DomainParticipant, DataWriter or DataReader). e.g. 01.0f.22.ba.3b.47.ab.3c.00.00.00.00|00.00.01.c1.

Topic

DDS isolation abstraction to encapsulate subscriptions and publications. Each Topic is uniquely identified by a topic name and a topic type name (name of the data type it transmits).

See Fast DDS documentation for further information.