[Accessibility-handlers] what is expert handlers

[Alexander Surkov]

Hello.

Here I'll try to continue the discussion based on Pete's comments (
https://lists.linux-foundation.org/pipermail/accessibility-handlers/2008-April/000349.htmland
https://lists.linux-foundation.org/pipermail/accessibility-handlers/2008-April/000350.html
).

1. The case of browser EH plug-inWhen browser doesn't support the certain
XML dialect (it doesn't know how to expose it to AT) then browser EH plug-in
is used. This plug-in is needed to expose the XML content to AT via AT API.

1.1. Implementation of browser EH plug-in

1.1.1. C++ implementation (usage of plug-in mechanism of browser)

1.1.1.1. What mechanisms does Firefox have?
Firefox has plug-in mechanism and XPCOM mechanism to extend browser. IIRC
plug-in mechanism is used to write new control elements (for example it's
used to add Java applet and Flash support). XPCOM mechanism is used to add
new functionality (provide new components and interfaces). Possibly we can
use XPCOM mechanism to implement browser EH plug-in (by Gecko SDK usage).

1.1.1.2. Gecko SDK and Gecko accessibility.
In the meantime Gecko SDK doesn't contain accessibility interfaces (though I
think it may be fixed easy enough). But Gecko accessibility module doesn't
have interfaces to allow EH plug-in be integrated into accessibility module.
We need integration because a) accessibility module supports common things
like ARIA that shouldn't be reimplemented by browser EH plug-in and b)
browser EH plug-in should integrate XML content into existing accessible
tree of the browser. I think in the meantime the current state fo Gecko
accessibility is a bit far to provide similar ability. But for sure we could
think about Gecko accessibility SDK to fit these needs.

1.1.1.3. Disadvantages.
There is one big disadvantage: browser EH plugin should be implemented for
each browser (no code sharing).

1.1.2. XBL/XTF implementation.
It is also Firefox only thing. XTF+XBL allows to implement new XML dialects
for Firefox (the great example is XForms extension). We could think how to
add accessibility support for this stuff (I put initial thoughts at
http://wiki.mozilla.org/Accessibility/CustomWidgets). But again no code
sharing.

1.1.3. JS implementation.
The great stuff we don't need to reimplement browser EH plugin for each
browser every time. Could we think about extension of JavaScript to
introduce new objects (like there is some JS extension for Java
http://developer.mozilla.org/en/docs/Core_JavaScript_1.5_Reference#LiveConnect_Class_Reference)?
But here there is biggest disadvantage: how many years do we need before
browsers will support that?

2. AT EH plug-in.
I still don't get how it can be used. If for example browser EH plugin
expose XML content to AT via AT APIs and AT uses AT APIs then where is the
place for AT EH plug-in? An example would be really good.

3. XML dialect a11y support.
I still don't get how the certain XML dialect should be exposed via AT API
(either by browser or browser EH plugin). I think somewhere here ontologies
should play their own role. But I don't see how. Any comments?

Thank you for your answers and comments.
Alexander.


On Tue, Apr 29, 2008 at 3:38 AM, Pete Brunet <brunet at us.ibm.com> wrote:

>
> >1) What is expert handlers?
> >It is the way to link the client software (like Firefox) and server
> software (screen readers) in order to expose XML languages (like MathML) to
> server software (make it accessible).
>
> PB: yes - but I think of client software in terms of a COM client and in
> that case the AT is the MSAA/IA2 COM client and the browser is the COM
> server
>
> >2) How does it look?
> >There is mediator that transforms information about XML language used on
> the certain web page (in the case of web browser) into some XML structure
> (by RDF/OWL usage). This XML structure should be exposed to AT (screen
> readers). Here I can see two possible approaches: AT deals with XML
> structure or there is another mediator that transform that XML structure to
> the certain AT API calls (like IA2 or ATK).
>
> PB:  Maybe this is not the right way do to it, but what I was thinking was
> that when the browser encountered the XML it would activate an EH, which
> would be written in code that could implement MSAA/IA2 (or ATK) and which
> would then parse the XML, build its own structure, provide UI (key handlers)
> to navigate the structure, fire a11y events, e.g. when a EH node received
> focus, and responsd to a11y requests for information about the object which
> currently has focus.
>
> >If the item above makes sense then I have following up questions:
> >1) Why do we need the mediator and why do we need to use RDF/OWL? Doesn't
> AT API allow to expose interested XML languages directly?
>
> PB: I don't understand the question.
>
> >2) How should it look for accessible XML languages like HTML. Will
> something be changed in their handling?
>
> PB: I don't think so.
>
> I will answer your other post in a few minutes.
>
> *Pete Brunet*
>
> IBM Accessibility Architecture and Development
> 11501 Burnet Road, MS 9022E004, Austin, TX 78758
> Voice: (512) 838-4594, Cell: (512) 689-4155
> Ionosphere: WS4G
>
>
>
>  *"Alexander Surkov" <surkov.alexander at gmail.com>*
> Sent by: accessibility-handlers-bounces at lists.linux-foundation.org
>
> 04/17/2008 02:26 AM
>   To
> accessibility-handlers at a11y.org  cc
>   Subject
> [Accessibility-handlers] what is expert handlers
>
>
>
>
> Hi.
>
> Originally I look for the way how to make accessible MathML in Firefox, I
> look for ideas and any experience in this field. I ran through expert
> handlers pages and tried to catch general idea. Unfortunately I didn't find
> any technical details how it should helps with MathML accessibility. So I'll
> try to form some questions and in some cases I'll try to give my
> understanding of this.
>
> 1) What is expert handlers?
> It is the way to link the client software (like Firefox) and server
> software (screen readers) in order to expose XML languages (like MathML) to
> server software (make it accessible).
>
> 2) How does it look?
> There is mediator that transforms information about XML language used on
> the certain web page (in the case of web browser) into some XML structure
> (by RDF/OWL usage). This XML structure should be exposed to AT (screen
> readers). Here I can see two possible approaches: AT deals with XML
> structure or there is another mediator that transform that XML structure to
> the certain AT API calls (like IA2 or ATK).
>
> If the item above makes sense then I have following up questions:
> 1) Why do we need the mediator and why do we need to use RDF/OWL? Doesn't
> AT API allow to expose interested XML languages directly?
> 2) How should it look for accessible XML languages like HTML. Will
> something be changed in their handling?
>
> Thank you for advice.
> Alexander._______________________________________________
> Accessibility-handlers mailing list
> Accessibility-handlers at lists.linux-foundation.org
> https://lists.linux-foundation.org/mailman/listinfo/accessibility-handlers
>
>
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