Accessibility infrastructure

This repository contains the DBus interface definitions for AT-SPI (Assistive Technology Service Provider Interface) — the core of an accessibility stack for free software systems. It also contains the basic daemons of the accessibility stack, the ATK library to make applications and GUI toolkits accessible, and the internal hooks between AT-SPI and ATK.

The version control repository and bug tracker are at https://gitlab.gnome.org/GNOME/at-spi2-core/

You can visit an ever-changing roadmap in devel-docs/roadmap.md.

To write accessible applications, look into atk or your programming language's bindings for the xml DBus interfaces mentioned below.

While this module started within the GNOME project's umbrella, it is not used only in GNOME. Other sources of relevant information about AT-SPI and Accessibility include:

• GNOME Accessibility wiki
• KDE Accessibility wiki
• Accessibility documentation for GNOME users

Documentation

• ATK reference documentation
• libatspi reference documentation

Development resources

• Development guide for the accessibility infrastructure
• Code coverage report for the test suite
• Container registry for CI images
• Continuous integration pipelines
• Development documentation

Summary of this repository's contents

• xml - DBus interfaces for accessibility, described in DBus's XML introspection format. Ideally, your programming language's implementation of DBus makes use of these files to generate callable bindings.

• bus - Launcher for the session's accessibility bus; see its README.md for details.

• registryd - Daemon that keeps track of accessible applications in the user's session, and lets them talk to each other and to assistive technologies (ATs) like screen readers.

• atk - GObject-based API to implement accessible applications and GUI toolkits. It is not mandatory to use this library for an accessible application; your application or toolkit can use bindings to the xml DBus APIs directly.

• atspi - Hand-written binding for the xml DBus interface above, for use from C with GObject. This is not normally what you would use; use a language-specific binding instead. This module is for use mainly by atk-adaptor below.

• atk-adaptor - Translates from the ATK API to the atspi API. Application programmers can ignore this and just consider it as an implementation detail.

• dbind - DBus utilities for use by atspi above. atspi was written before the more modern C bindings like GDBusConnection were available, so there is a lot of hand-written IPC here.

• droute - DBus utilities for use by atk-adaptor above.

• Documentation for the Gitlab Continuous Integration pipeline.

Historical note

Versions 1.x of AT-SPI were based on CORBA for inter-process communication (IPC), using GNOME's ORBit implementation thereof. During the GNOME 2 and 3 release series, CORBA was phased out in favor of DBus, a more modern IPC mechanism.

The original CORBA interfaces for AT-SPI were based on Java's implementation of accessibility. Later, these CORBA interfaces were translated to DBus. This is why the interfaces sometimes have a 1990s feeling to them.

The project was started with a D-Bus performance review, the results of which are available on the GNOME wiki. Keep in mind that the D-Bus AT-SPI design documents on this page have not been kept up to date.

    https://wiki.gnome.org/Accessibility/Documentation/GNOME2/ATSPI2-Investigation