Crate zbus

Expand description

zbus

This is the main subcrate of the zbus project, that provides the API to interact with D-Bus. It takes care of the establishment of a connection, the creation, sending and receiving of different kind of D-Bus messages (method calls, signals etc) for you.

Status: Stable.

Getting Started

The best way to get started with zbus is the book, where we start with basic D-Bus concepts and explain with code samples, how zbus makes D-Bus easy.

Example code

Client

This code display a notification on your Freedesktop.org-compatible OS:

use std::{collections::HashMap, error::Error};

use zbus::{Connection, dbus_proxy};
use zvariant::Value;

#[dbus_proxy(
    interface = "org.freedesktop.Notifications",
    default_service = "org.freedesktop.Notifications",
    default_path = "/org/freedesktop/Notifications"
)]
trait Notifications {
    fn notify(
        &self,
        app_name: &str,
        replaces_id: u32,
        app_icon: &str,
        summary: &str,
        body: &str,
        actions: &[&str],
        hints: &HashMap<&str, &Value<'_>>,
        expire_timeout: i32,
    ) -> zbus::Result<u32>;
}

// Although we use `async-std` here, you can use any async runtime of choice.
#[async_std::main]
async fn main() -> Result<(), Box<dyn Error>> {
    let connection = Connection::session().await?;

    // `dbus_proxy` macro creates `NotificationProxy` based on `Notifications` trait.
    let proxy = NotificationsProxy::new(&connection).await?;
    let reply = proxy.notify(
        "my-app",
        0,
        "dialog-information",
        "A summary",
        "Some body",
        &[],
        &HashMap::new(),
        5000,
    ).await?;
    dbg!(reply);

    Ok(())
}

Server

A simple service that politely greets whoever calls its SayHello method:

use std::{error::Error, future::pending};
use zbus::{ConnectionBuilder, dbus_interface};

struct Greeter {
    count: u64
}

#[dbus_interface(name = "org.zbus.MyGreeter1")]
impl Greeter {
    // Can be `async` as well.
    fn say_hello(&mut self, name: &str) -> String {
        self.count += 1;
        format!("Hello {}! I have been called {} times.", name, self.count)
    }
}

// Although we use `async-std` here, you can use any async runtime of choice.
#[async_std::main]
async fn main() -> Result<(), Box<dyn Error>> {
    let greeter = Greeter { count: 0 };
    let _ = ConnectionBuilder::session()?
        .name("org.zbus.MyGreeter")?
        .serve_at("/org/zbus/MyGreeter", greeter)?
        .build()
        .await?;

    // Do other things or go to wait forever
    pending::<()>().await;

    Ok(())
}

You can use the following command to test it:

$ busctl --user call org.zbus.MyGreeter /org/zbus/MyGreeter org.zbus.MyGreeter1 SayHello s "Maria"
s "Hello Maria! I have been called 1 times."

Blocking API

While zbus is primarily asynchronous (since 2.0), blocking wrappers are provided for convenience.

Compatibility with async runtimes

zbus is runtime-agnostic and should work out of the box with different Rust async runtimes. However, in order to achieve that, zbus spawns a thread per connection to handle various internal tasks. If that is something you would like to avoid, you need to:

Use ConnectionBuilder and disable the internal_executor flag.
Ensure the internal executor keeps ticking continuously.

Moreover, by default zbus makes use of async-io for all I/O, which also launches its own thread to run its own internal executor.

Special tokio support

Since tokio is the most popular async runtime, zbus provides an easy way to enable tight integration with it without you having to worry about any of the above: Enabling the tokio feature and disabling the default async-io feature:

[dependencies]
zbus = { version = "2", default-features = false, features = ["tokio"] }

That’s it! No threads launched behind your back by zbus (directly or indirectly) now and no need to tick any executors etc. 😼

Note: On Windows, the async-io feature is currently required for UNIX domain socket support, see the corresponding tokio issue on GitHub.

Re-exports

pub use zbus_names as names;

pub use zvariant;

Modules

blocking

The blocking API.

fdo

D-Bus standard interfaces.

xml

Introspection XML support (xml feature)

Structs

Connection

A D-Bus connection.

ConnectionBuilder

A builder for zbus::Connection.

Guid

A D-Bus server GUID.

InterfaceDeref

Opaque structure that derefs to an Interface type.

InterfaceDerefMut

Opaque structure that mutably derefs to an Interface type.

InterfaceRef

Wrapper over an interface, along with its corresponding SignalContext instance. A reference to the underlying interface may be obtained via InterfaceRef::get and InterfaceRef::get_mut.

Message

A D-Bus Message.

MessageBuilder

A builder for Message

MessageFields

A collection of MessageField instances.

MessageHeader

The message header, containing all the metadata about the message.

MessagePrimaryHeader

The primary message header, which is present in all D-Bus messages.

MessageSequence

A position in the stream of Message objects received by a single zbus::Connection.