/** \page page_daemon PipeWire Daemon

The PipeWire daemon is the central process that manages data exchange between
devices and clients.

Typically general, users run one PipeWire daemon that listens for incoming
connections and manages devices. Clients (including the \ref
page_session_manager) are separate processes that talk to the daemon using the
PipeWire socket (default: `$XDG_RUNTIME_DIR/pipewire-0`). This approach
provides provides address-space separation between the privileged daemon and
non-privileged clients.

@dot
digraph pw {
  compound=true;
  node [shape="box"];

  subgraph cluster_pw {
	rankdir="TB";
	label="PipeWire daemon";
	style="dashed";

	subgraph cluster_prot_native {
		label="pipewire-module-protocol-native";
		style="solid";
		socket [label="$XDG_RUNTIME_DIR/pipewire-0"];
		mod_impl [label="module implementation"];

		socket -> mod_impl;
	}
	core [label="PipeWire Core"];
	alsa [label="PipeWire ALSA support"];

	mod_impl -> core;
	core -> alsa;
  }

  kernel

  client1 [ label="Media Player" ];
  client2 [ label="Audio Software" ];
  sm [ label="Session Manager", style="dotted" ];

  client1 -> socket;
  client2 -> socket;
  sm -> socket;
  alsa -> kernel;
}
@enddot

As shown above, the protocol is handled by the \ref
page_module_protocol_native. From PipeWire's point-of-view this module is just
another module.

\section sec_config Configuration Files

On startup, the daemon reads a configuration file to configure itself.
It executes a series of commands listed in the config file. The lookup order
for configuration files are:

- `$XDG_CONFIG_HOME/pipewire/pipewire.conf` (usually `$HOME/.config/pipewire/pipewire.conf`)
- `$sysconfdir/pipewire/pipewire.conf` (usually `/etc/pipewire/pipewire.conf`)
- `$datadir/pipewire/pipewire.conf` (usually `/usr/share/pipewire/pipewire.conf`)

The first configuration file found is loaded, the PipeWire daemon does not
currently combine configuration files.

The environment variables `PIPEWIRE_CONFIG_DIR`, `PIPEWIRE_CONFIG_PREFIX`
and `PIPEWIRE_CONFIG_NAME` can be used to specify an alternative config
directory, subdirectory and filename, respectively.

\subsection sec_config_format Configuration File Format

PipeWire's configuration file format is JSON. In addition to true JSON,
PipeWire also understands a more compact JSON representation where
`"` can be omitted around strings, no trailing commas are required and
`:` or `=` can be used to separate object keys from their values.
Also, `#` can be used to start a comment until the end of the line.

The configuration file format is grouped into sections.  A section is
either a dictionary (`{}`) or an array (`[]`). Dictionary and array entries
are separated by whitespace and may be simple value assignment, an array or
a dictionary. For example:

```
# A dictionary section
context.properties = {
       # Keys often have a dot notation
       core.daemon = true
}

# An array section containing three dictionary objects
context.modules = [
    # a dictionary object with one key assigned to a string
    { name = libpipewire-module-protocol-native }
    { name = libpipewire-module-profiler }

    # a dictionary object with two keys, one assigned to a string
    # the other one to an array of strings
    { name = libpipewire-module-portal
      flags = [ ifexists nofail ]
    }
]
```

Allowed configuration file sections are:

- **context.properties**  (dictionary):   These   properties  configure  the
  pipewire instance.

- **context.spa-libs** (dictionary): Maps plugin features with globs to a
  spa library.

- **context.modules** (array): Each entry in the array is a dictionary with
  the name of the module to load, including optional args and flags. Most
  modules support being loaded multiple times.

- **context.objects** (array):  Each entry in the array is a dictionary con‐
  taining the factory to create an object from and optional  extra  argu‐
  ments specific to that factory.

- **context.exec**  (array): Each entry in the array is dictionary containing
  the path of a program to execute on startup and optional args. This ar‐
  ray usually contains an entry to start the session manager.


\section sec_logging Logging

The `PIPEWIRE_DEBUG` environment variable can be used to enable
more debugging. The format is:

`<level>[<category>;...]`

- `<level>` specifies the log level:
  + `0`: no logging is enabled
  + `1`: Error logging is enabled
  + `2`: Warnings are enabled
  + `3`: Informational messages are enabled
  + `4`: Debug messages are enabled
  + `5`: Trace messages are enabled. These messages can be logged
     	from the realtime threads.

- `<category>`:  Specifies a string category to enable. Many categories
     	  can be separated by commas. Current categories are:
  + `connection`: to log connection messages

*/