1. User Interface

eProsima DDS Router is a user application executed from the command line and configured through a YAML configuration file.

1.1. Source Dependency Libraries

eProsima DDS Router depends on Fast DDS fastrtps and fastcdr libraries. In order to correctly execute the Router, make sure that fastrtps and fastcdr are properly sourced.

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


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

1.2. Application Arguments

The DDS Router application supports several input arguments:



Long option


Default Value

Help Argument



Version Argument



Configuration File Argument



Readable File Path


Reload Time Argument



Unsigned Integer


Debug Argument



Log Verbosity Argument


info warning error


Log Filter Argument




1.2.1. Help Argument

It shows the usage information of the application.

Usage: Fast DDS Router
Connect different DDS networks via DDS through LAN or WAN.
It will build a communication bridge between the different Participants included in the provided configuration file.
To stop the execution gracefully use SIGINT (C^) or SIGTERM (kill) signals.
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: ./DDS_ROUTER_CONFIGURATION.yaml].
-r --reload-time    Time period in seconds to reload configuration file. This is needed when FileWatcher functionality is not available (e.g. config file is a symbolic link). Value 0 does not reload file. [Default: 0].
-t --timeout        Set a maximum time in seconds for the Router to run. Value 0 does not set maximum. [Default: 0].

Debug options
-d --debug          Set log verbosity to Info (Using this option with --log-filter and/or --log-verbosity will head to undefined behaviour).
    --log-filter     Set a Regex Filter to filter by category the info and warning log entries. [Default = "DDSROUTER"].
    --log-verbosity  Set a Log Verbosity Level higher or equal the one given. (Values accepted: "info","warning","error" no Case Sensitive) [Default = "warning"].

1.2.2. Version Argument

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

1.2.3. Configuration File Argument

Please refer to Configuration File for more information on how to build this configuration file.

1.2.4. Reload Time Argument

Set the Reload Timer in seconds.

1.2.5. Timeout Argument

This argument allow to set a maximum time while the application will be running. Setting this argument will set the number of seconds the application will run until it is killed. While the application is waiting for timeout, it is still possible to kill it via signal. Default value 0 means that the application will run forever (until kill via signal).

1.2.6. Debug Argument

This argument enables the DDS Router logs so the execution can be followed by internal debugging information. This argument sets Log Verbosity Argument to info and Log Filter Argument to DDSROUTER. For more information about debugging options, refer to Log.


If this argument is used with any of the other arguments of debugging, the behavior depends on the order of parser of the arguments.

1.2.7. Log Verbosity Argument

Set the verbosity level so only log messages with equal or higher importance level are shown.

1.2.8. Log Filter Argument

Set a regex string as filter. Only log messages with a category that matches this regex will be printed (ERROR messages will be always shown unless Log Verbosity Argument is set to ERROR).

1.3. Configuration File

A DDS Router requires one and only one YAML configuration file as the operation of this application is configured via this YAML configuration file. Please refer to Configuration for more information on how to build this configuration file.

This YAML configuration file must be passed as argument to the DDS Router when executed. If no configuration file is provided as argument, the DDS Router will attempt to load a file named DDS_ROUTER_CONFIGURATION.yaml that must be in the same directory where the application is executed. If no configuration file is passed as argument, and the default configuration file does not exist in the current directory, the application will fail.

1.4. Reload Topics

The topics that the DDS Router is routing could be changed at runtime. Including topics in configuration’s allowlist will create new Writers and Readers for each Participant in the Router. Removing a topic from allowlist will disable this topic, and so it will stop routing data in such topic. Be aware that disabling a topic does not eliminate the entities of that topic. So, if a topic has been active before, the Writers and Readers will still be present in the DDS Router and will still receive data.

There exist two methods to reload the list of allowed topics, an active and a passive one. Both methods work over the same configuration file with which the DDS Router has been initialized.

1.4.1. File Watcher

A File Watcher is a process that runs in the background and tracks changes in the DDS Router configuration file. Every time the file is changed, the OS sends a notification, and the File Watcher listens such notification and interacts with the DDS Router in order to reload the topics. This event occurs every time the configuration file is saved.

FileWatcher is used in every DDS Router execution by default. However, this method does not work properly in specific scenarios where the file being watched is not a real file but a link (e.g. Kubernetes executions).

1.4.2. Reload Timer

A timer can be set in order to periodically reload the configuration file. The configuration file will be automatically reloaded according to the specified time period.

1.5. Log

Log module of DDS Router uses the Fast DDS logging module. This log has 3 severity levels: INFO, WARNING and ERROR. Every log has also a category associated. This is how a log looks like:

Date                     Category         Severity     Log message                   Function
2022-11-16 14:58:13.375 [MODULE_SUBMODULE Error] It has happen ... because of ... -> Function main

Every log entry has several parts:

  • Date: format: year-month-day hour::minute::second::millisecond with millisecond accuracy. This is the time when the log was added to the log queue, not when it is printed.

  • Category: Reference to the module where the log was raised. It is used to filter logs.

  • Severity: Could be Info, Warning or Error.

  • Log message: The actual log message.

  • Function: Name of the function or method that has produced this log entry.


For INFO logs to be compiled, the DDS Router must have been compiled with CMake option CMAKE_BUILD_TYPE=Debug, or compiled with CMake option LOG_INFO=ON.

If Fast DDS has been compiled in debug mode, it will print the logs of the DDS Router and Fast DDS mixed. In order to skip Fast DDS logs, compile fastrtps library with CMake option -DLOG_NO_INFO=ON or CMAKE_BUILD_TYPE different to Debug, or use the argument ``

1.6. Close Application

In order to stop a DDS Router application, use one of the following OS signals:

1.6.1. SIGINT

Send an interruption SIGINT | ^C signal (signal value 2) to the process. Press Ctrl + C in the terminal where the process is running.

1.6.2. SIGTERM

Send an interruption SIGTERM signal (signal value 15) to the process by executing the command kill <pid> in a different terminal, where <pid> is the id of the process running the DDS Router. Use the ps or top programs to check the processes’ ids.

1.6.3. TIMEOUT

Setting a maximum amount of seconds that the application will work using argument --timeout will close the application once the time has expired.