Re: [g-a-devel] Overview of DBus ATSPI design

[Rob Taylor <rob taylor codethink co uk>]

Li Yuan wrote:
> On 一, 2008-01-07 at 17:14 +0000, Rob Taylor wrote:
>> == Process Architecture ==
>>
>> (see attached png)
>>
>> In the current system, all IPC is direct between processes, and there
>> is
>> the registry daemon that deals with passing events and monitoring X
>> events and sending DeviceEventListener events.
>>
>> The D-Bus session bus already acts as a central process for passing
>> messages and signals. In this respect it is well suited to acting as a
>> replacement for the registry daemon. The D-Bus session bus also has
>> advanced filtering mechanisms for deciding what signals a process
>> wishes
>> to receive. Messages can be filtered by object path, interface, and
>> even
>> message body. This could allow AT-SPI clients to register to receive
>> certain events from particular applications, and cut down on IPC
>> traffic.
>>
>> A process will still be required to monitor and forward device events
>> to
>> the message bus. The D-Bus bus daemon could be modified to perform
>> this
>> task, but it is just as easy to use a separate process. The use of a
>> separate process will mean the D-Bus session bus can be used. This is
>> already present in all distributions using D-Bus, making acceptance
>> easier.
> 
> Yes, this is what I am thinking about. One question is how do we handle
> remote applications that show on the current display?

Well, as we've discussed in previous mails, the options for a
user/distro are:

 1) use a modified sshd that forwards your session bus along with the
X11 connection [1], or

 2) enable TCP connections for the session bus for the display and set
up your DBUS_SESSION_BUS_ADDRESS environment variable to point to that
address/port.

It'd be great to be able to support 1). I've had contract the occasional
volunteer to write such a patch for openssh, but I haven't seen any code
yet. It shouldn't be too hard to write though getting it in openssh
itself may take a while. Distros could always choose to ship with such a
patch.

Thanks,
Rob

[1] http://lists.freedesktop.org/archives/dbus/2007-March/007199.html

> Li
> 


-- 
Rob Taylor, Codethink Ltd. -  http://codethink.co.uk