Re: what is AT-SPI ?

["Steve Lee" <steve fullmeasure co uk>]

On 5/24/07, Gautam Ravi <gautam ravichandran gmail com> wrote:
> I read some where that after doing all these things, I have to export all
> these to AT-SPI layer. What is this AT-SPI layer?
> Is it really needed to my system (Mine is an embedded system).
>
> Is AT-SPI a protocol ? or Daemon ? .. Is it very essential ?
> Can I do without this?
> Will my custom widget be accessible without this layer? or Should I also
> install this in to my system?

Hi Guatam, I'm pretty new to the Linux side but this summary that I
just sent to someone might help

"The Gnome a11y infrastructure allows end user assistive
technology (AT) programs such as screen readers to get rich
information about an application's UI state. Application's use the ATK
library to serve information but for stock GTK+ widgets the GAIL
library does this automatically when the Gnome Accessibility option
for Enable Assistive Technology is turned on. ATs access the
information via AT-SPI protocols (Corba based). KDE are now looking at
implementing it as well and IAccessibility2 extends Microsofts MSAA to
be very similar semantically.

http://live.gnome.org/GAP
"

So AT-SPI is the platform, consisting of a standard protocol
implemented on CORBA (there's talk of D-BUS for KDE) . ATs use AT-SPI
directly to access a11y info from applications like yours and *IS* a
vital part of the infrastructure. (I'm not sure how that pans out if
you're embedded as I expect CORBA is quite resource hungry.) ATK
provides a library api that applications use to serve up the a11y info
for widgets. They don't need to deal with AT-SPI directly. A third
component is a broker or registry that manages event traffic allowing
applications to source and ATS to sink various broadcast-based message
flows by subscription.

This presentation from Bill Haneman is good.
http://www.gnome.org/~billh/ArchitecturalOverview.odp
and there's more here from Mozilla
http://www.mozilla.org/access/unix/architecture

That's the overview, perhaps someone could correct or expand on this
and provide the practical steps?

--
Steve Lee
--
Open Source Assistive Technology Software
PowerTalk - your presentations can speak for themselves
www.fullmeasure.co.uk