PX4 · hamishwillee · Mar 13, 2025 · Feb 9, 2025 · Feb 26, 2025 · Feb 26, 2025
diff --git a/en/middleware/uorb.md b/en/middleware/uorb.md
@@ -125,7 +125,7 @@ Versioned messages include an additional field `uint32 MESSAGE_VERSION = x`, whe
 
 Versioned and non-versioned messages are separated in the file system:
 
-- Non-versioned topic message files and service message files remain in the [`msg/`](https://github.com/PX4/PX4-Autopilot/tree/main/msg) and [`srv/`](https://github.com/PX4/PX4-Autopilot/tree/main/srv) directories, respectively.
+- Non-versioned topic message files and [server service](../ros2/user_guide.md#px4-ros-2-service-servers) message files remain in the [`msg/`](https://github.com/PX4/PX4-Autopilot/tree/main/msg) and [`srv/`](https://github.com/PX4/PX4-Autopilot/tree/main/srv) directories, respectively.
 - The current (highest) version of message files are located in the `versioned` subfolders ([`msg/versioned`](https://github.com/PX4/PX4-Autopilot/tree/main/msg/versioned) and [`srv/versioned`](https://github.com/PX4/PX4-Autopilot/tree/main/srv/versioned)).
 - Older versions of messages are stored in nested `msg/px4_msgs_old/` subfolders ([`msg/px4_msgs_old/msg/`](https://github.com/PX4/PX4-Autopilot/tree/main/msg/px4_msgs_old/msg) and [`msg/px4_msgs_old/srv/`](https://github.com/PX4/PX4-Autopilot/tree/main/msg/px4_msgs_old/srv)).
   The files are also renamed with a suffix to indicate their version number.

diff --git a/en/middleware/uxrce_dds.md b/en/middleware/uxrce_dds.md
@@ -308,7 +308,7 @@ By default the client is started on localhost UDP port `8888` with no additional
 Environment variables are provided that override some [UXRCE-DDS parameters](../advanced_config/parameter_reference.md#uxrce-dds-client).
 These allow users to create custom startup files for their simulations:
 
-- `PX4_UXRCE_DDS_NS`: Use this to specify the topic [namespace](#customizing-the-topic-namespace).
+- `PX4_UXRCE_DDS_NS`: Use this to specify the topic [namespace](#customizing-the-namespace)).
 - `ROS_DOMAIN_ID`: Use this to replace [UXRCE_DDS_DOM_ID](../advanced_config/parameter_reference.md#UXRCE_DDS_DOM_ID).
 - `PX4_UXRCE_DDS_PORT`: Use this to replace [UXRCE_DDS_PRT](../advanced_config/parameter_reference.md#UXRCE_DDS_PRT).
 
@@ -347,16 +347,16 @@ Therefore,
   For more information see [DDS Topics YAML](#dds-topics-yaml) below.
   :::
 
-## Customizing the Topic Namespace
+## Customizing the Namespace
 
-Custom topic namespaces can be applied at build time (changing [dds_topics.yaml](https://github.com/PX4/PX4-Autopilot/blob/main/src/modules/uxrce_dds_client/dds_topics.yaml)) or at runtime (which is useful for multi vehicle operations):
+Custom topic and service namespaces can be applied at build time (changing [dds_topics.yaml](https://github.com/PX4/PX4-Autopilot/blob/main/src/modules/uxrce_dds_client/dds_topics.yaml)) or at runtime (which is useful for multi vehicle operations):
 
 - One possibility is to use the `-n` option when starting the [uxrce_dds_client](../modules/modules_system.md#uxrce-dds-client) from command line.
   This technique can be used both in simulation and real vehicles.
 - A custom namespace can be provided for simulations (only) by setting the environment variable `PX4_UXRCE_DDS_NS` before starting the simulation.
 
 ::: info
-Changing the namespace at runtime will append the desired namespace as a prefix to all `topic` fields in [dds_topics.yaml](https://github.com/PX4/PX4-Autopilot/blob/main/src/modules/uxrce_dds_client/dds_topics.yaml).
+Changing the namespace at runtime will append the desired namespace as a prefix to all `topic` fields in [dds_topics.yaml](https://github.com/PX4/PX4-Autopilot/blob/main/src/modules/uxrce_dds_client/dds_topics.yaml) and all [service servers](#dds-ros-2-services).
 Therefore, commands like:
 
 ```sh
@@ -490,6 +490,17 @@ Add a topic to the `subscriptions_multi` section to:
 You can arbitrarily change the configuration.
 For example, you could use different default namespaces or use a custom package to store the message definitions.
 
+## DDS (ROS 2) Services
+
+PX4 uXRCE-DDS middleware supports [ROS 2 services](https://docs.ros.org/en/jazzy/Concepts/Basic/About-Services.html).
+These are remote procedure calls, from one node to another, which return a result.
+They simplify communication between ROS 2 nodes and PX4 by encapsulating and associating the request and response topics, ensuring that replies are only returned to the specific requesting user.
+
+A service server is the entity that will accept a remote procedure request, perform some computation on it, and return the result.
+For example, the `/fmu/vehicle_command` service server defined in [`px4_msgs::srv::VehicleCommand`](https://github.com/PX4/px4_msgs/blob/main/srv/VehicleCommand.srv) can be called by ROS 2 applications to send PX4 [VehicleCommand](../msg_docs/VehicleCommand.md) uORB messages and receive PX4 [VehicleCommandAck](../msg_docs/VehicleCommandAck.md) uORB messages in response.
+
+For a list of services, details and examples see the [service documentation](../ros2/user_guide.md#px4-ros-2-service-servers) in the ROS 2 User Guide.
+
 ## Fast-RTPS to uXRCE-DDS Migration Guidelines
 
 These guidelines explain how to migrate from using PX4 v1.13 [Fast-RTPS](../middleware/micrortps.md) middleware to PX4 v1.14 `uXRCE-DDS` middleware.

diff --git a/en/ros2/multi_vehicle.md b/en/ros2/multi_vehicle.md
@@ -23,7 +23,7 @@ param set UXRCE_DDS_KEY $((px4_instance+1))
 By doing so, `UXRCE_DDS_KEY` will always coincide with [MAV_SYS_ID](../advanced_config/parameter_reference.md#MAV_SYS_ID).
 :::
 
-Moreover, when `px4_instance` is greater than zero, a unique ROS 2 [namespace prefix](../middleware/uxrce_dds.md#customizing-the-topic-namespace) in the form `px4_$px4_instance` is added:
+Moreover, when `px4_instance` is greater than zero, a unique ROS 2 [namespace prefix](../middleware/uxrce_dds.md#customizing-the-namespace) in the form `px4_$px4_instance` is added:
 
 ```sh
 uxrce_dds_ns="-n px4_$px4_instance"

diff --git a/en/ros2/px4_ros2_msg_translation_node.md b/en/ros2/px4_ros2_msg_translation_node.md
@@ -318,15 +318,15 @@ The example describes the process of updating the `VehicleAttitude` message defi
 
    For example, update `msg/versioned/VehicleAttitude.msg` from:
 
-   ```.msg
+   ```txt
    uint32 MESSAGE_VERSION = 3
    uint64 timestamp
    ...
    ```
 
    to
 
-   ```.msg
+   ```txt
    uint32 MESSAGE_VERSION = 4  # Increment
    uint64 timestamp
    float32 new_field           # Make definition changes