Connecting to Devices

Before interacting with OCA objects, the controller must establish a network connection to the device. libaes70 provides integration points for different networking libraries, so you can choose the one that fits your project.

Controller connections are supported for libuv, boost::asio, and lwIP (for embedded platforms). Choose the integration that fits your project.

An example for establishing a connection can be found in examples/simple_controller:

static void connect()
{
  std::cerr << "Trying to connect to device." << std::endl;
  libuv::tcp::connect<aes70::controller::connection>("127.0.0.1", 65123,
      [&](const char *error,
          std::shared_ptr<aes70::controller::connection> con) {
        if (!error)
        {
          std::cerr << "connected." << std::endl;
          con->set_keepalive_interval(1000);
          connected(con);
          subs.add(con->onclose(
              [](const aes70::controller::connection &) { closed(); }));
        }
        else
        {
          std::cerr << "connection failed: " << error << std::endl;
          closed();
        }
      });
}

int main(int argc, const char **argv)
{

  connect();

  return uv_run(uv_default_loop(), UV_RUN_DEFAULT);
}

Note

It is generally recommended to use set_keepalive_interval to enable keepalive messages. Otherwise, the detection of connection loss can be unreliable.

Observing a connection (auto-reconnect)

For long-running controllers that should stay connected to a device across temporary disconnects, use aes70::controller::observe_connection. It establishes a connection using a connect functor (e.g. from your networking integration’s connector_factory) and, when the connection closes or the initial connect fails, automatically retries. You supply a callback that runs each time a connection is established; typically it returns a subscription from observe_path or other observers so that when the connection drops, those subscriptions are cleaned up and reconnect is triggered.

• Header: aes70/controller/observe_connection.hpp
• Connect functor: Use libuv::tcp::connector_factory, aes70::boost::tcp::connector_factory, or lwip::tcp::connector_factory (each parameterized with aes70::controller::connection).
• Return value: A subscription. Keep it alive for as long as you want the controller to maintain and re-establish the connection; dropping it stops reconnection.

The esp32_mute_controller example (examples/esp32_mute_controller) uses observe_connection with the lwIP connector factory to connect to a device, observe a mute at a path, and toggle it on a timer.

Detecting connection loss

When not using observe_connection, long-running applications that must handle the loss of connections should use the onclose() method to handle connection close events and re-create a connection after some time interval.

Note

Note that the subscription returned from onclose() must be kept alive until the connection is lost. See aes70::controller::subscription for details.