Intelligent Input Bus
The main goals of the IBus project include: The draft "Specification of IM engine Service Provider Interface" document from the Northeast Asia OSS Forum Work Group 3 recommends bus-centric IM framework architectures with a bus implementation (similar to dbus). According to the specification, SCIM-1.4 is not considered suitable for further development as it is developed in C++, which usually causes ABI transition problems. Since then, succeeding projects like IM-BUS (led by James Su) and SCIM-2 (led by Zheng Hu) were started. However, both projects are suspended. Therefore, Huang Peng from Red Hat established the IBus project to prove the idea of IM-BUS by using Python, D-Bus and GLib rather than implementing the functions recommended by CJK OSS forum. In spite of that, IBus has already gained community acceptance, and FreeBSD and many Linux distribution such as Fedora and Ubuntu already have IBus in their package repositories. IBus became the new default input method framework in Fedora 11, and replaced SCIM in Ubuntu 9.10. IBus is developed in C and Python, thus avoiding the C++ ABI transition problem of SCIM <1.4.14. IBus provides most of its functionality through services. There are three kinds of services:

IBus employs D-Bus to communicate among ibus-daemon, services, and IM clients such as terminal emulators, editors and web browsers. ibus-daemon manages all clients and services by receiving registrations from services, and sending D-Bus message to corresponding services and IM client. It implements XIM protocol, and has GTK and Qt input method modules. ibus-m17n is an IME that uses input methods and corresponding icons in the m17n database. Unlike ibus-table which supports plain tables, m17n input methods also support states, whose labels are displayed on the IBus panel (language bar). M17n input methods also support surrounding text, consequently, languages such as Thai and IMs such as plain Zhuyin that require this feature are supported through ibus-m17n. ibus-table, developed by Yu Wei Yu, is an IME that loads tables of input methods which do not need complicated logic to select words. Many structure-based Chinese input methods such as Cangjie and Wubi are supported this way. Officially released IM tables:
Motivation
The Intelligent Input Bus (IBus, pronounced as I-Bus) is an input method (IM) framework for multilingual input in Unix-like operating-systems. The name "Bus" comes from its bus-like architecture.