Sections in this file describe:
 - introduction and overview
 - low-level vs. high-level API
 - version numbers
 - options to the configure script
 - ABI stability policy

Introduction
===

D-Bus is a simple system for interprocess communication and coordination.

The "and coordination" part is important; D-Bus provides a bus daemon that does things like:
 - notify applications when other apps exit
 - start services on demand
 - support single-instance applications

See http://www.freedesktop.org/software/dbus/ for lots of documentation,
mailing lists, etc.

See also the file HACKING for notes of interest to developers working on D-Bus.

If you're considering D-Bus for use in a project, you should be aware
that D-Bus was designed for a couple of specific use cases, a "system
bus" and a "desktop session bus." These are documented in more detail
in the D-Bus specification and FAQ available on the web site.

If your use-case isn't one of these, D-Bus may still be useful, but
only by accident; so you should evaluate carefully whether D-Bus makes
sense for your project.

Note: low-level API vs. high-level binding APIs
===

A core concept of the D-Bus implementation is that "libdbus" is
intended to be a low-level API. Most programmers are intended to use
the bindings to GLib, Qt, Python, Mono, Java, or whatever. These
bindings have varying levels of completeness and are maintained as
separate projects from the main D-Bus package. The main D-Bus package
contains the low-level libdbus, the bus daemon, and a few command-line
tools such as dbus-launch.

If you use the low-level API directly, you're signing up for some
pain. Think of the low-level API as analogous to Xlib or GDI, and the
high-level API as analogous to Qt/GTK+/HTML.

Version numbers
===

D-Bus uses the common "Linux kernel" versioning system, where
even-numbered minor versions are stable and odd-numbered minor
versions are development snapshots.

So for example, development snapshots: 1.1.1, 1.1.2, 1.1.3, 1.3.4
Stable versions: 1.0, 1.0.1, 1.0.2, 1.2.1, 1.2.3

All pre-1.0 versions were development snapshots.

Development snapshots make no ABI stability guarantees for new ABI
introduced since the last stable release. Development snapshots are
likely to have more bugs than stable releases, obviously.

Configuration
===

dbus could be build by using autotools or cmake.

When using autotools the configure step is initiated by running ./configure
with our without additional configuration flags.

When using cmake the configure step is initiated by running the cmake
program with our without additional configuration flags.

Configuration flags
===

When using autools the dbus-specific configuration flags that can be given to
the ./configure program are these

  --enable-tests             enable unit test code
  --enable-verbose-mode      support verbose debug mode
  --enable-asserts           include assertion checks
  --enable-checks            include sanity checks on public API
  --enable-xml-docs          build XML documentation (requires xmlto)
  --enable-doxygen-docs      build DOXYGEN documentation (requires Doxygen)
  --enable-gcov              compile with coverage profiling instrumentation (gcc only)
  --enable-abstract-sockets  use abstract socket namespace (linux only)
  --enable-selinux           build with SELinux support
  --enable-dnotify           build with dnotify support (linux only)
  --enable-kqueue            build with kqueue support (*BSD only)
  --with-xml=libxml/expat           XML library to use
  --with-init-scripts=redhat        Style of init scripts to install
  --with-session-socket-dir=dirname Where to put sockets for the per-login-session message bus
  --with-test-socket-dir=dirname    Where to put sockets for make check
  --with-system-pid-file=pidfile    PID file for systemwide daemon
  --with-system-socket=filename     UNIX domain socket for systemwide daemon
  --with-console-auth-dir=dirname   directory to check for console ownerhip
  --with-dbus-user=<user>           User for running the DBUS daemon (messagebus)
  --with-gnu-ld                     assume the C compiler uses GNU ld [default=no]
  --with-tags[=TAGS]                include additional configurations [automatic]
  --with-x                          use the X Window System

When using the cmake build system the dbus-specific configuration flags that can be given
to the cmake program are these (use -D<key>=<value> on command line)

    CMAKE_BUILD_TYPE                   set dbus build mode - one of Debug|Release|RelWithDebInfo|MinSizeRel
    DBUS_BUILD_TESTS                   enable unit test code  default=ON
    DBUS_BUILD_X11                     Build X11-dependent code default=ON
    HAVE_CONSOLE_OWNER_FILE            enable console owner file (solaris only) ) default=ON
    DBUS_DISABLE_ASSERTS               Disable assertion checking default=OFF
    DBUS_DISABLE_CHECKS                Disable public API sanity checking default=OFF
    DBUS_ENABLE_ABSTRACT_SOCKETS       enable support for abstract sockets (linux only) default=ON
    DBUS_ENABLE_ANSI                   enable -ansi -pedantic gcc flags default=OFF
    DBUS_ENABLE_DNOTIFY                build with dnotify support (linux only) default=ON
    DBUS_ENABLE_VERBOSE_MODE           support verbose debug mode default=ON
    DBUS_ENABLE_DOXYGEN_DOCS           build DOXYGEN documentation (requires Doxygen) default=ON
    DBUS_GCOV_ENABLED                  compile with coverage profiling instrumentation (gcc only) default=OFF
    DBUS_INSTALL_SYSTEM_LIBS           install required system libraries default (windows only) =OFF
    DBUS_USE_EXPAT                     Use expat (== ON) or libxml2 (==OFF) default=ON [1]
    DBUS_USE_NONCE_TCP_DEFAULT_ADDRESS Use nonce tcp default address default=OFF
    DBUS_USE_OUTPUT_DEBUG_STRING       enable win32 debug port for message output default=OFF

    [1] requires installed development package of the related dependency


API/ABI Policy
===

Now that D-Bus has reached version 1.0, the objective is that all
applications dynamically linked to libdbus will continue working
indefinitely with the most recent system and session bus daemons.

 - The protocol will never be broken again; any message bus should
   work with any client forever. However, extensions are possible
   where the protocol is extensible.

 - If the library API is modified incompatibly, we will rename it
   as in http://ometer.com/parallel.html - in other words,
   it will always be possible to compile against and use the older
   API, and apps will always get the API they expect.

Interfaces can and probably will be _added_. This means both new
functions and types in libdbus, and new methods exported to
applications by the bus daemon.

The above policy is intended to make D-Bus as API-stable as other
widely-used libraries (such as GTK+, Qt, Xlib, or your favorite
example). If you have questions or concerns they are very welcome on
the D-Bus mailing list.

NOTE ABOUT DEVELOPMENT SNAPSHOTS AND VERSIONING

Odd-numbered minor releases (1.1.x, 1.3.x, 2.1.x, etc. -
major.minor.micro) are devel snapshots for testing, and any new ABI
they introduce relative to the last stable version is subject to
change during the development cycle.

Any ABI found in a stable release, however, is frozen.

ABI will not be added in a stable series if we can help it. i.e. the
ABI of 1.2.0 and 1.2.5 you can expect to be the same, while the ABI of
1.4.x may add more stuff not found in 1.2.x.

NOTE ABOUT STATIC LINKING

We are not yet firmly freezing all runtime dependencies of the libdbus
library. For example, the library may read certain files as part of
its implementation, and these files may move around between versions.

As a result, we don't yet recommend statically linking to
libdbus. Also, reimplementations of the protocol from scratch might
have to work to stay in sync with how libdbus behaves.

To lock things down and declare static linking and reimplementation to
be safe, we'd like to see all the internal dependencies of libdbus
(for example, files read) well-documented in the specification, and
we'd like to have a high degree of confidence that these dependencies
are supportable over the long term and extensible where required.

NOTE ABOUT HIGH-LEVEL BINDINGS

Note that the high-level bindings are _separate projects_ from the
main D-Bus package, and have their own release cycles, levels of
maturity, and ABI stability policies. Please consult the documentation
for your binding.

The cygwin dbus port is included in master branch of
dbus git repository since 1.3.1.

See cygwin/README for more informations about
the cygwin dbus port.

The cygwin port of dbus is maintained by:

http://sourceware.org/cygwinports/

On 2009-10-21 I (Tor Lillqvist <tml@iki.fi>) cherry-picked a bunch of
commits from the dbus4win-noncetcp branch of the dbus4win repository
to (my clone of) dbus upstream's master branch.

The dbus4win repository is at least currently at
git://repo.or.cz/dbus4win.git

I went through the commits done to the dbus4win-noncetcp branch since
the dbus-1.2.14 tag, i.e. commit f719d454329a1a54ff2d569feaf10ceee7cead50.

The following commits were left out because they either 0) were
already upstream, 1) seemed broken, or 2) seemed pointless to me,
especially if the commit message didn't say much. For each commit left
out, below is three lines: its id, the first log comment line, and an
explanation why I left it out.

f719d454329a1a54ff2d569feaf10ceee7cead50
configure.in: not all gccs support -Wno-pointer-sign
already upstream

6eddb6e1229b617ad44c8d61107983229dc7d589
configure.in: fail abstract socket test gracefully when cross-compilin
already upstream

c54dd9eefa5ed0d54be3b09cf30c12f05130fda1
r783: one ifdef lesser
probably pointless

93c288ca3e86e7760d3ac3fa6490257c1b6dc544
r783: compile if ENOMEM or EINTR is undefined.
huh, ENOMEM and EINTR is defined in the Microsoft C library

4f4ba13357da15c35a9d4ad111bf972a5d0d5db0
r783: introduced _dbus_daemon_release() function called in _dbus_loop_quit()...
this can't be right, there can be nested dbus loops afaik

124eb334324472a10de2c7e0a1455d353431f08f
unix build fixes against windbus-svn
can't be right to make a char* const when the code below then assigns through it

594bd19a0c45822d8763871e3491d99beb4d22cb
introduce DBUS_DIR_SEPERATOR and make use of it. On windows, disable some system service tests
"forward" slashes work fine on Windows, no need to uglify code with DBUS_DIR_SEPARATOR

cd2cdb3457f72cf058d5b19796ee691ceca6b52c
r783: introduced DBUS_CLEANUP_OLD_SERVICES that does cleanup prev zombie-instances...
unsure about this. something specific to KDE-on-Windows?

eeedba5b2f5b008819619764943caddd52441adf
build fixes for OS X, xcode 3.1.2, gcc 4.2.1
doesn't apply, seems to be upstream?

7dc7f71cf3003e006f6e177b5460d14a7cdbf2de
configure.in: fix pthread detection
doesn't apply

05b37fa87b1f6aa670de9007879f53a8198a7a89
configure.in: suppress -fPIC, -fPIE for W32
doesn't apply

b0d14fed92d9f539cd3478e72dc2f3ea75f3941a
configure.in: only check for wspiapi.h on Windows
nah, no harm checking for it on UNIX too

1724fc10e516e2d570537d522d8608abba90be5e
prototypes cleanup
related to cd2cdb3457f72cf058d5b19796ee691ceca6b52c which was skipped above

DBus Daemon for Windows CE/Windows Mobile 6.5
=============================================

Bugs in upstream for any window version:
* MoveFileExA < 0 result check bug
* double dbus_free somewhere I forgot where (check in -ugly)
* alignment issue
* CreateProcess process information handle leak
* _dbus_getsid NULL vs INVALID_HANDLE_VALUE
* win_account_to_sid

Customisation
=============

1) At installation, the following registry value should be set to the
installation directory of the dbus installation (the directory
containing the bin, etc, share folders):

HKLM\Software\freedesktop\DBus\Install Directory

2) Instead of environment variable DBUS_VERBOSE, use
HKLM\Software\freedesktop\DBus\Verbose

2) The keyring directory is MYDOCUMENTS\dbus-keyrings, not
HOMEPATH\.dbus-keyrings.


Compilation
===========

./configure --host=arm-mingw32ce CPPFLAGS=-I/path/to/expat/include LDFLAGS=-L/path/to/expat/lib

A recent version of libtool is required, with this change:

2010-02-28  Pierre Ossman  <ossman@ossman.lkpg.cendio.se>  (tiny change)
            Ralf Wildenhues <Ralf.Wildenhues@gmx.de>

       Fix deplibs check fallback for 64-bit Windows and Windows CE.
       * libltdl/m4/libtool.m4 (_LT_CHECK_MAGIC_METHOD): Accept file formats
       'pe-arm-wince' and 'pe-x86-64'.  Add note about consistency with ...
       * libltdl/config/ltmain.m4sh (func_win32_libid): ... the respective
       pattern here; sync pattern from the former.
       * tests/deplibs-mingw.at (deplibs without file command): New
       file, new test.
       * Makefile.am (TESTSUITE_AT): Update.
       * NEWS: Update.


MB vs WCHAR
===========

Windows CE only supports the Unicode interface, while DBus Daemon uses
the Multi-Byte interface on Windows by default.  The glue code does
not support multibyte in all cases.  In particular, the _mbsrchr
function is not correctly implemented.  It could be correctly
implemented, or dbus daemon could use the wchar interface more
consistently on all Windows targets.  For now, the Windows CE port
will only work for filesystems without some weird characters in file
names.  Is this a serious limitation?


Known Issues
============

Autolaunch is broken so far.

Environment variables are faked.  Some are punted to the registry, but
in any case they can not be used reliably for IPC.

The test suite is not ported yet.

dbus-pipe.c:
 * Uses libc file descriptors.  Needed for --print-address and
   --print-pid which probably don't work yet.

dbus-sysdeps-win.c:
 * Backtraces have been disabled.
 * _dbus_fd_set_close_on_exec Not supported, maybe we should disable
   the warning.
 * SearchPathA: Uses HKLM\\Software\\freedesktop\\DBus\\Install Directory
   to locate binaries.

This README.windbus file below originates from the "windbus" fork. It
does not reflect reality here. Changes from both windbus and the
separate "dbus4win" fork have been merged into this code repository,
as applicable.

----------------------------------------
Windows port of the freedesktop.org D-Bus
----------------------------------------

Requirements
------------
- cmake version >= 2.4.4 see http://www.cmake.org
- installed libxml2 or libexpat from http://82.149.170.66/kde-windows/win32libs

Build
-----

unix
1. install cmake and libxml or libexpat
2. get dbus sources
3. mkdir dbus-build
4. cd dbus-build
5. cmake <dbus-src-root>/cmake or cmake -DDBUS_USE_EXPAT=on <dbus-src-root>/cmake in case libexpat should de used
5. make
6. make install

win32
1. Install your prefered compiler
	- Mingw from www.mingw.org
	- Visual C++ 2005 Express/Studio

2. Install libxml2 or libexpat packages from
     http://82.149.170.66/kde-windows/win32libs
   into a subdir win32libs in your program installation eg
     - german  => "c:\Programme\win32libs"
     - english => "c:\Program Files\win32libs"

3. download and install the most recent CMake version from http://www.cmake.org/files/

4. apply dbus-win.patch: 'patch -p0 -i dbus-win.patch'

5. open command shell and run in the created build folder which resides side by side
   to the D-Bus sources:
   	- for mingw:
		cmake -G "MinGW Makefiles" <options> ..\<dbus-source-root>\cmake
	- for Visual C++
		cmake ..\<dbus-source-root>\cmake

7. build


Tests
-----
(when build with the Visual C++ IDE the *.exe files are
in the bin/Debug and bin/Release folder)

 - dbus library check
		bin\dbus-test.exe .\test\data

 - bus daemon check
		bin\bus-test.exe .\test\data

 - check available names
		bin\test_names.exe

 - check if dbus-daemon is accessable
		bin\dbus-send.exe --session --type=method_call --print-reply --dest=org.freedesktop.DBus / org.freedesktop.DBus.ListNames method return sender=org.freedesktop.DBus -> dest=:1.4 array [ 	      string "org.freedesktop.DBus"string ":1.4"]

 - start dbus-daemon
		* set DBUS_VERBOSE=0  (=1 for getting debug infos)
		* start bin\dbus-daemon --session
		* bin\dbus-send.exe  --dest=org.freedesktop.DBus --print-reply --type=method_call / org.freedesktop.DBus.StartServiceByName string:org.freedesktop.DBus.TestSuiteEchoService  uint32:455 method return sender=org.freedesktop.DBus -> dest=:1.8 uint32 2



Some build options
-------------
    key                        description                            default value
    ---                        -----------                            -------------
DBUS_USE_EXPAT              "Use expat (== ON) or libxml2 (==OFF)         OFF
DBUS_DISABLE_ASSERTS        "Disable assertion checking"                  OFF
DBUS_BUILD_TESTS            "enable unit test code"                       ON
DBUS_ENABLE_ANSI            "enable -ansi -pedantic gcc flags"            OFF
DBUS_ENABLE_GCOV            "compile with coverage profiling
                             instrumentation (gcc only)"                  OFF
DBUS_ENABLE_VERBOSE_MODE    "support verbose debug mode"                  ON
DBUS_DISABLE_CHECKS         "Disable public API sanity checking"          OFF
DBUS_INSTALL_SYSTEM_LIBS    "install required system libraries
                             (mingw: libxml2, libiconv, mingw10)"         OFF
CMAKE_BUILD_TYPE            "build type (== debug) or (== release)        release



Developers
----------

Running the tests in Visual Studio:

 To successfully run the tests by the IDE you must add
 the FULL patch to test\data in your build directory
 (e.g. c:\dbus\build\test\data)
 in something like
  -> Project Settings
    -> Debugging
       -> Command line arguments



FAQ
---

- How much work remains till DBUS win32 can be merged with the main project?

There are some patches outstanding and the most effort is required in
discussions with the main dbus team how to implement some parts. One of
the main dbus team estimated the open work to one fulltime week.
http://lists.freedesktop.org/archives/dbus/2006-November/006264.html

I assume they will answer ALL your questions, and they are very
interested in fully supporting win32.

- How far is WinDBus from being usable for production ?
dbus comes with a test suite which is used on unix to guarantate
production quality and this test suite runs mostly. There are some
test not running and we need help to get them running.

In the pratice I and some other people are using dbus for at least more
than a half year in conjunction with kde on windows without any problems.


- On UNIX D-Bus uses UNIX sockets to communicate (correct me if I'm wrong).
  What is used on Windows ?

tcp sockets, there are some efforts to get named pipe running, but some
design problems of the win32 api, we are not able to solve without
bigger changes to the dbus code base let us stop this effort.


- Do you have any clue if dbus-win32 can run in a Windows CE environment?

I was told that windows ce does not have posix function
open/close/select/... and dbus code uses such function in some area.


- Do you know if the C++ binding made by OpenWengo will be easily portable to Windows?

We have already ported the OpenWengo dbus-c++ binding, see in WinDBus svn  (http://sf.net/projects/windbus)
The related test applicationa are running well.


TODO
----

February 2007:

- all changes of dbus-win.patch should become part of the official D-Bus code

- all code currently disabled by DBUS_WIN_FIXME should work

- clean up:
    * bus/bus-service-win.c
    * bus/dir-watch.c
    * dbus/dbus-spawn-win.c
    * dbus/dbus-sysdeps-util-win.c
    * dbus/dbus-sysdeps-win.c


see also:
http://lists.freedesktop.org/archives/dbus/2006-July/005076.html