Service callback never called with a custom interfaces using strings

Hardware description: ESP32
RTOS: FreeRTOS
Installation type: idf component
Version or commit hash: humble

I made two custom interfaces, one typical AddThreeInts, and one ping :

The callback method in both cases looks like that :

void ping_callback(const void* request, void* response) {
    ESP_LOGI(TAG, "Received ping request");
}

When I create the service using my AddThreeInts or the example AddTwoInts, the callback is called properly.
But when I use my ping interfaces, it never goes into the callback...

Steps to reproduce the issue

How I create the service :

    // Create ping server with default config (Reliable QoS)
    const rosidl_service_type_support_t* type_support =
        ROSIDL_GET_SRV_TYPE_SUPPORT(ble2ros_interfaces, srv, Ping);
    RCCHECK(rclc_service_init_default(&ping_srv, &node, type_support, ping_srv_name));

    // Create executor
    executor = rclc_executor_get_zero_initialized_executor();
    RCCHECK(rclc_executor_init(&executor, &support.context, 4, &allocator));

    // Add ping server to executor
    RCCHECK(rclc_executor_add_service(
            &executor,
            &ping_srv,
            &ping_req,
            &ping_rsp,
            ping_callback
    ));

Could you share the .srv files of your custom interfaces?

Here is my Ping.srv from ble2ros_interfaces/srv (I have the package built and setup in ROS2 and in the extra_packages of the uROS component)

# Sends a ping to the BT Mesh provisioner
# Receives the response from provisioner
string ping
---
string pong

are you initializing the strings? https://micro.ros.org/docs/tutorials/advanced/handling_type_memory/

Not at all... Didn't think I had to do that but it makes sense.
If I understand correctly, I should use the automated memory handling from micro-ros-utilities ? And I can customize the string sizes using the micro_ros_utilities_memory_conf_t struct ?

And I must do it for both the request and response message ? The utility will know that those are service messages and do it automatically ?

You need to do it for both messages, req and res. You can assign memory directly or use the utilities. In the case that is a simple string, maybe is easier to assign memory manually. You have instructions for both approaches in the link above.

Please provide feedback so we can close this issue.

Works like a charm, thanks a lot ! I assigned memory directly like that : (writing it in case someone find this issue too)

    // Initializing request and response msg
    ping_req.ping.capacity = 100;
    ping_req.ping.data = (char*) malloc(ping_req.ping.capacity * sizeof(char));

    ping_rsp.pong.capacity = 100;
    ping_rsp.pong.data = (char*) malloc(ping_rsp.pong.capacity * sizeof(char));

Quick last question, it doesn't appear possible to create two services with the ESP32, the second one always makes an error. I saw here :micro-ROS/micro_ros_arduino#442 that the Teensy only supports one services. Is it also the case with the ESP32 ? (If not I will probably look further into that or make another issue)

micro_ros_espidf_component/colcon.meta

Line 43 in f426aa2

"-DRMW_UXRCE_MAX_SERVICES=1",