Original author(s) | Bart Massey |
---|---|
Developer(s) | Jamey Sharp, Josh Triplett, Bart Massey |
Initial release | 2001 |
Stable release |
1.12 / 18 May 2016
|
Written in | C |
Operating system | POSIX |
Type | |
License | MIT License |
Website | xcb |
XCB (X protocol C-language Binding) is a library implementing the client-side of the display server protocol. XCB is written in the C programming language and distributed under the MIT License. The project was started in 2001 by Bart Massey and aims to replace Xlib.
XCB was designed as a smaller, modernized replacement for Xlib, previously the primary C library for communicating with the X window system, coinciding with a more complete overhaul of the X implementation that took place during the early 2000s. The main goals of XCB are to
The required size reduction is achieved primarily by restricting XCB's scope to handling the X protocol and omitting Xlib functionality such as its extensive utility library, much of which saw little use by applications. This results in a factor thirty reduction of the compiled library size (as of 2004). Secondary goals include making the C interface asynchronous, facilitating better multithreading and making it easier to implement extensions (via XML protocol descriptions).
The core and extension protocol descriptions are in XML, with a program written in Python creating the C bindings. (Previous versions used XSLT and M4.)
A further goal is to be able to use these protocol descriptions to create protocol documentation, more language bindings, and server-side stubs.
Massey and others have worked to prove key portions of XCB formally correct using Z notation. (Xlib has long been known to contain errors.)
Xlib/XCB provides application binary interface compatibility with both Xlib and XCB, providing an incremental porting path. Xlib/XCB uses the protocol layer of Xlib, but replaces the Xlib transport layer with XCB, and provides access to the underlying XCB connection for direct use of XCB. Xlib/XCB allows an application to open a single connection to the X display server and use both XCB and Xlib, possibly through a mixture of libraries designed for one or the other.