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 CONTRIBUTING.md 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.

Security
==

If you find a security vulnerability that is not known to the public,
please report it privately to dbus-security@lists.freedesktop.org
or by reporting a freedesktop.org bug that is marked as
restricted to the "D-BUS security group" (you might need to "Show
Advanced Fields" to have that option).

On Unix systems, the system bus (dbus-daemon --system) is designed
to be a security boundary between users with different privileges.

On Unix systems, the session bus (dbus-daemon --session) is designed
to be used by a single user, and only accessible by that user.

We do not currently consider D-Bus on Windows to be security-supported,
and we do not recommend allowing untrusted users to access Windows
D-Bus via TCP.

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 or without additional configuration flags. dbus requires GNU Make
(on BSD systems, this is typically called gmake) or a "make" implementation
with compatible extensions.

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

Configuration flags
===

When using autotools, run "./configure --help" to see the possible
configuration options and environment variables.

When using cmake, inspect README.cmake to see the possible
configuration options and environment variables.

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.

Bootstrapping D-Bus on new platforms
===

A full build of D-Bus, with all regression tests enabled and run, has some
dependencies which themselves depend on D-Bus, either for compilation or
for some of *their* regression tests: GLib, dbus-glib and dbus-python are
currently affected.

To avoid circular dependencies, when bootstrapping D-Bus for the first time
on a new OS or CPU architecture, you can either cross-compile some of
those components, or choose the build order and options carefully:

* build and install D-Bus without tests
  - do not use the --enable-modular-tests=yes configure option
  - do not use the --enable-tests=yes configure option
* build and install GLib, again without tests
* use those versions of libdbus and GLib to build and install dbus-glib
* ... and use those to install dbus-python
* rebuild libdbus; this time you can run all of the tests
* rebuild GLib; this time you can run all of the tests

This file describes how to compile dbus using the cmake build system

Requirements
------------
- cmake version >= 2.6.0 see http://www.cmake.org
- installed libexpat see http://sourceforge.net/projects/expat/
    unsupported RelWithDebInfo builds could be fetched
    from http://sourceforge.net/projects/kde-windows/files/expat/

Building
--------

Win32 MinGW-w64|32
1. install mingw-w64 from http://sourceforge.net/projects/mingw-w64/
2. install cmake and libexpat
3. get dbus sources
4. unpack dbus sources into a sub directory (referred as <dbus-src-root> later)
5. mkdir dbus-build
6. cd dbus-build
7. run
    cmake -G "MinGW Makefiles" [<options, see below>] <dbus-src-root>/cmake
    mingw32-make
    mingw32-make install

Win32 Microsoft nmake
1. install MSVC 2010 Express Version from http://www.microsoft.com/visualstudio/en-us/products/2010-editions/visual-cpp-express
2. install cmake and libexpat
3. get dbus sources
4. unpack dbus sources into a sub directory (referred as <dbus-src-root> later)
5. mkdir dbus-build
6. cd dbus-build
7. run
    cmake -G "NMake Makefiles" [<options, see below>] <dbus-src-root>/cmake
    nmake
    nmake install

Win32 Visual Studio 2010 Express IDE
1. install MSVC 2010 Express Version from http://www.microsoft.com/visualstudio/en-us/products/2010-editions/visual-cpp-express
2. install cmake and libexpat
3. get dbus sources
4. unpack dbus sources into a sub directory (referred as <dbus-src-root> later)
5. mkdir dbus-build
6. cd dbus-build
7. run
      cmake -G "Visual Studio 10" [<options, see below>] <dbus-src-root>/cmake
8a. open IDE with
      vcexpress dbus.sln
8b. for immediate build run
      vcexpress dbus.sln /build

Win32 Visual Studio 2010 Professional IDE
1. install MSVC 2010 Professional Version
2. install cmake and libexpat
3. get dbus sources
4. unpack dbus sources into a sub directory (referred as <dbus-src-root> later)
5. mkdir dbus-build
6. cd dbus-build
7. run
      cmake -G "Visual Studio 10" [<options, see below>] <dbus-src-root>/cmake
8a. open IDE with
      devenv dbus.sln
8b. for immediate build run
      devenv dbus.sln /build

Linux
1. install cmake and libexpat
2. get dbus sources
3. unpack dbus sources into a sub directory (referred as <dbus-src-root> later)
4. mkdir dbus-build
5. cd dbus-build
6. run
    cmake -G "<for available targets, see cmake --help for a list>" [<options, see below>] <dbus-src-root>/cmake
    make
    make install

For other compilers see cmake --help in the Generators section

Configuration flags
-------------------

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). The listed values
are the defaults (in a typical build - some are platform-specific).

// Choose the type of build, options are: None(CMAKE_CXX_FLAGS or
// CMAKE_C_FLAGS used) Debug Release RelWithDebInfo MinSizeRel.
CMAKE_BUILD_TYPE:STRING=Debug

// Include path for 3rdparty packages
CMAKE_INCLUDE_PATH:PATH=

// Library path for 3rdparty packages
CMAKE_LIBRARY_PATH:PATH=

// Install path prefix, prepended onto install directories.
CMAKE_INSTALL_PREFIX:PATH=C:/Program Files/dbus


// enable unit test code
DBUS_BUILD_TESTS:BOOL=ON

// The name of the dbus daemon executable
DBUS_DAEMON_NAME:STRING=dbus-daemon

// Disable assertion checking
DBUS_DISABLE_ASSERT:BOOL=OFF

// Disable public API sanity checking
DBUS_DISABLE_CHECKS:BOOL=OFF

// enable -ansi -pedantic gcc flags
DBUS_ENABLE_ANSI:BOOL=OFF

// build DOXYGEN documentation (requires Doxygen)
DBUS_ENABLE_DOXYGEN_DOCS:BOOL=OFF

// enable bus daemon usage statistics
DBUS_ENABLE_STATS:BOOL=OFF

// support verbose debug mode
DBUS_ENABLE_VERBOSE_MODE:BOOL=ON

// build XML  documentation (requires xmlto or meinproc4)
DBUS_ENABLE_XML_DOCS:BOOL=ON

// install required system libraries
DBUS_INSTALL_SYSTEM_LIBS:BOOL=OFF

// session bus default listening address
DBUS_SESSION_BUS_LISTEN_ADDRESS:STRING=autolaunch:

// session bus fallback address for clients
DBUS_SESSION_BUS_CONNECT_ADDRESS:STRING=autolaunch:

// system bus default address (only useful on Unix)
DBUS_SYSTEM_BUS_DEFAULT_ADDRESS:STRING=unix:path=/var/run/dbus/system_bus_socket

win32 only:
// enable win32 debug port for message output
DBUS_USE_OUTPUT_DEBUG_STRING:BOOL=OFF

gcc only:
// compile with coverage profiling instrumentation
DBUS_GCOV_ENABLED:BOOL=OFF

solaris only:
// enable console owner file
HAVE_CONSOLE_OWNER_FILE:BOOL=ON

// Directory to check for console ownership
DBUS_CONSOLE_OWNER_FILE:STRING=/dev/console

// Linux only:
// enable inotify as dir watch backend
DBUS_BUS_ENABLE_INOTIFY:BOOL=ON

*BSD only:
// enable kqueue as dir watch backend
DBUS_BUS_ENABLE_KQUEUE:BOOL=ON

x11 only:
// Build with X11 auto launch support
DBUS_BUILD_X11:BOOL=ON


Note: The above mentioned options could be extracted after
configuring from the output of running "<maketool> help-options"
in the build directory. The related entries start with
CMAKE_ or DBUS_.


How to compile in dbus into clients with cmake
----------------------------------------------

To compile dbus library into a client application with cmake
the following cmake commands are required:

1. call find_package to find dbus package

find_package(DBus1)

2. after specifing targets link dbus into target

add_executable(test test.c)
target_link_libraries(test ${DBus1_LIBRARIES})

Adding ${DBus1_LIBRARIES} to targets also adds required dbus
include dirs and compiler definitions by default. There is
no need to add them with include_directories and add_definitions.

To compile against dbus installed in a non standard location
specify -DDBus1_DIR=<dbus-install-root>/lib[64]/cmake/DBus1
on cmake command line.

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

The cygwin port of dbus is maintained by:

http://sourceware.org/cygwinports/

Launchd[1,2] replaces init, inetd and cron on Mac OS X since 10.4 "Tiger".
dbus uses this service to provide a common session bus address for each user
and so deprecates the X11 enabled dbus-launcher.

[1] http://developer.apple.com/MacOsX/launchd.html
[2] http://launchd.macosforge.org/


Setup
===

Configure with --enable-launchd and --without-x (X11 should not harm but it's
simply not necessary any more)
After installation, to prevent a reboot, load the dbus session starter into
launchd by executing:
$ launchctl load /Library/LaunchAgents/org.freedesktop.dbus-session.plist

You can change the launch agent dir via configure, but it's not recommended.
Make sure to execute the above line as the actual user for which you want to
use a session bus since launchd manages its agents on a per user basis.


How it works
===

Launchd allocates a socket and provides the unix path to it via the variable
DBUS_LAUNCHD_SESSION_BUS_SOCKET in launchd's environment. Every process
spawned by launchd (or dbus-daemon, if stared by launchd) can access it through
its own environment. Other processes can query launchd for it by executing:
$ launchctl getenv DBUS_LAUNCHD_SESSION_BUS_SOCKET
However, this is normally done by the dbus client lib for you.

If launchd start dbus-daemon with a config file containing a "launchd:env=FOO"
address, as the default session config does with env=DBUS_LAUNCHD_SESSION_BUS_SOCKET,
the daemon will get the file descriptor from launchd and start listening on it.
The environment variable is used to get the actual socket path which is passed
to every service spawned by dbus-daemon as a result from autolaunch messages.
Please note that it's not possible to start dbus-daemon manually when using a
"launchd:" address. Only child processes of launchd can access the above
mentioned file descriptor!

To create custom buses just set up an other launch agent. As a quick start copy
/Library/LaunchAgents/org.freedesktop.dbus-session.plist, change the label
to i.e. "org.freedesktop.dbus-foo" and change the SecureSocketWithKey value,
i.e. to "DBUS_LAUNCHD_FOO_BUS_SOCKET". This environment variable has to be set
in the config file for your new bus in the <listen> element (see session.config).
Then edit your /Library/LaunchAgents/org.freedesktop.dbus-foo.plist to start
dbus-daemon with "--config-file=/opt/local/etc/dbus-1/foo.conf" instead of
"--session". Now load the new plist onto launchd as described in the setup
section of this document.
Executing "launchctl export" should now give you two sockets, one in
DBUS_LAUNCHD_SESSION_BUS_SOCKET and the new DBUS_LAUNCHD_FOO_BUS_SOCKET.
To connect to this new bus use "launchd:env=DBUS_LAUNCHD_FOO_BUS_SOCKET".

Since Mac OS X 10.5 "Leopard" you can also configure launchd to start
dbus-daemon on demand as soon as some process connects to the socket. Since
it's broken on 10.4 this feature is disabled per default. Look at
/Library/LaunchAgents/org.freedesktop.dbus-session.plist to change it.

On the client side, the envvar DBUS_SESSION_BUS_ADDRESS can be normally used
but if it's not set, launchd is queried for the session bus socket.

Running D-Bus clients with Valgrind
====

When running programs using libdbus in Valgrind, some special care needs to be
taken so as to avoid incorrect detection of leaks in libdbus. To avoid these
false positives, do the following:

* Grab a copy of the D-Bus source code

* Run configure with the --enable-developer and --with-valgrind options

* Run make

* Either make sure your code calls dbus_shutdown() (at least while running in
  Valgrind) or set DBUS_MESSAGE_CACHE=0 in your environment

* Run Valgrind on your program with the /path/to/dbus/source/dbus/.libs in your
  LD_LIBRARY_PATH

Your Valgrind log should now be free of any (spurious) libdbus-related leaks.

For the curious, the DBUS_MESSAGE_CACHE=0 is required because by
default, libdbus uses a recyclable pool of message structs. These help
performance a bit.

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

Features and completeness
-------------------------
The windows port of dbus provides the dbus-1 library and mostly
applications which are already available on unix. These applications
are: dbus-daemon, dbus-launch, dbus-monitor and dbus-send.
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 yet and there is help needed to get them running.

Supported compilers
-------------------
On windows Microsoft Visual Studio 2010 (Express and professional variants)
and mingw-w64|32 are known to work.

Building
--------
DBus can be built on windows using automake or cmake. See the
file INSTALL for more information.

windbus and dbus4win Ports
--------------------------
The Windows ports from the windbus and dbus4win projects has been merged
into the freedesktop git master branch, as applicable. The spec has been
updated with windows specific stuff.


Tests
-----
 - run complete test suite
     make check
   or
     ctest [-V]

 - dbus library check
    ctest [-V] -R test-dbus

 - bus daemon check
    ctest [-V] -R test-bus

 - check available names
    ctest [-V] -R test-names

 - 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 session dbus-daemon
    either by running
        bin\dbus-launch
    or
        start bin\dbus-daemon --session

    Before running these commands you may execute
        set DBUS_VERBOSE=1
    for getting debug infos


 - call function registerd in dbus
    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

    note: When building with the Visual C++ IDE the *.exe files are in
          the bin/Debug and bin/Release folder, not in the bin folder.


FAQ
---

- 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 four years 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?

  dbus has been ported to wince, see README.wince for more information

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

  The OpenWengo dbus-c++ binding has been ported to windows see in WinDBus svn
  (http://sf.net/projects/windbus)
  The related test applications are running well.


TODO
----

October 2010:

- the code wrapped with DBUS_WIN_FIXME should be inspected if it required for windows

- create a dbus setup installer

- implement system bus and system bus service starter
  see http://windbus.svn.sourceforge.net/viewvc/windbus/trunk/bus/bus-service-win.c
  for a starting point

- implement a real login session bus
  The scope parameter of the autolaunch meta protocol could be extended to support user
  specific session busses (like already done with the amarok bundled dbus which use a
  shared memory area named "DBusDaemonAddressInfo:<username>".
  Also the dbus installer should start a session bus on user login.

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.