# NAME Protocol::DBus - D-Bus in pure Perl # SYNOPSIS (NB: Examples below assume use of [subroutine signatures](https://metacpan.org/pod/perlsub#Signatures).) For blocking I/O: my $dbus = Protcol::DBus::Client::system(); # Authentication and “Hello” call/response: $dbus->initialize(); $dbus->send_call( path => '/org/freedesktop/DBus', interface => 'org.freedesktop.DBus.Properties', member => 'GetAll', destination => 'org.freedesktop.DBus', signature => 's', body => [ 'org.freedesktop.DBus' ], )->then( sub ($resp_msg) { .. } ); my $msg = $dbus->get_message(); For non-blocking I/O, it is recommended to use an event loop. This distribution includes some connectors to simplify that work: - [Protocol::DBus::Client::IOAsync](https://metacpan.org/pod/Protocol%3A%3ADBus%3A%3AClient%3A%3AIOAsync) (for [IO::Async](https://metacpan.org/pod/IO%3A%3AAsync)) - [Protocol::DBus::Client::Mojo](https://metacpan.org/pod/Protocol%3A%3ADBus%3A%3AClient%3A%3AMojo) (for [Mojolicious](https://metacpan.org/pod/Mojolicious)) - [Protocol::DBus::Client::AnyEvent](https://metacpan.org/pod/Protocol%3A%3ADBus%3A%3AClient%3A%3AAnyEvent) (for [AnyEvent](https://metacpan.org/pod/AnyEvent)) Example: my $loop = IO::Async::Loop->new(); my $dbus = Protcol::DBus::Client::IOAsync::login_session($loop); $dbus->initialize()->then( sub ($dbus) { return $dbus->send_call( … ); # same arguments as above }, )->finally( sub { $loop->stop() } ); $loop->run(); You can also interface with a manually-written event loop. See [the example](#example-using-manually-written-event-loop) below. # DESCRIPTION
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This is an original, pure-Perl implementation of client messaging logic for [the D-Bus protocol](https://dbus.freedesktop.org/doc/dbus-specification.html). It’s not much more than an implementation of the wire protocol; it doesn’t know about objects, services, or anything else besides the actual messages. This is fine, of course, if all you want to do is, e.g., replace an invocation of `gdbus` or `dbus-send` with pure Perl. If you want an interface that mimics D-Bus’s actual object system, you’ll need to implement it yourself or use something like [Net::DBus](https://metacpan.org/pod/Net%3A%3ADBus). (See ["DIFFERENCES FROM Net::DBus"](#differences-from-net-dbus) below.) # STATUS This project is in BETA status. While the API should be pretty stable now, breaking changes can still happen. If you use this module in your project, you **MUST** check the changelog before deploying a new version. Please file bug reports as appropriate. # EXAMPLES See [Protocol::DBus::Client](https://metacpan.org/pod/Protocol%3A%3ADBus%3A%3AClient) and the above samples for a starting point. Also see the distribution’s `examples/` directory. # DIFFERENCES FROM Net::DBus [Net::DBus](https://metacpan.org/pod/Net%3A%3ADBus) is an XS binding to [libdbus](https://www.freedesktop.org/wiki/Software/dbus/), the reference D-Bus implementation. It is CPAN’s most mature D-Bus implementation. There are several reasons why you might prefer this module instead, though, such as: - Net::DBus discerns how to send a method call via D-Bus introspection. While handy, this costs extra network overhead and requires an XML parser. With Protocol::DBus you give a signature directly to send a method call. - Protocol::DBus can work smoothly with any event system you like, including custom-written ones. (The distribution ships with connectors for three popular ones.) Net::DBus, on the other hand, expects you to use its own event loop, [Net::DBus::Reactor](https://metacpan.org/pod/Net%3A%3ADBus%3A%3AReactor). - Protocol::DBus has a considerably lighter memory footprint. - Protocol::DBus is pure Perl, so on most OSes you can fat-pack it for easy distribution. - Protocol::DBus exposes a simpler API. Of course, there are tradeoffs: most notably, Protocol::DBus’s API is simpler because it doesn’t attempt to implement D-Bus’s object system. (You never **need** the object system, but it can be a useful abstraction.) An XS-powered D-Bus library is also likely to outperform a pure-Perl one, introspection overhead notwithstanding. YMMV. BYOB. # NOTES - UNIX FD support requires that [Socket::MsgHdr](https://metacpan.org/pod/Socket%3A%3AMsgHdr) be loaded at authentication time. - Certain OSes may require [Socket::MsgHdr](https://metacpan.org/pod/Socket%3A%3AMsgHdr) in order to authenticate via a UNIX socket. (Linux, notably, does not.) It depends if your OS can send local socket credentials without using [sendmsg(2)](http://man.he.net/man2/sendmsg). - EXTERNAL and DBUS\_COOKIE\_SHA1 authentications are supported. # EXAMPLE USING MANUALLY-WRITTEN EVENT LOOP my $dbus = Protcol::DBus::Client::system(); $dbus->blocking(0); my $fileno = $dbus->fileno(); # You can use whatever polling method you prefer; # the following is just for demonstration: vec( my $mask, $fileno, 1 ) = 1; while (!$dbus->initialize()) { if ($dbus->init_pending_send()) { select( undef, my $wout = $mask, undef, undef ); } else { select( my $rout = $mask, undef, undef, undef ); } } $dbus->send_call( .. ); # same parameters as above while (1) { my $wout = $dbus->pending_send() || q<>; $wout &&= $mask; select( my $rout = $mask, $wout, undef, undef ); if ($wout =~ tr<\0><>c) { $dbus->flush_write_queue(); } if ($rout =~ tr<\0><>c) { # It’s critical to get_message() until undef is returned. 1 while $dbus->get_message(); } } Life is easier if you use someone else’s event loop. :)