qemu/QMP
Mark Wu 1c1d46cc0b qmp: add test tool for QMP
Anthony wrote this quickly to aid in testing.  It's similar to qmp-shell with
a few important differences:

1) It is not interactive.  That makes it useful for scripting.

2) qmp-shell:

(QEMU) set_password protocol=vnc password=foo

3) qmp:

$ qmp set_password --protocol=vnc --password=foo

4) Extensible, git-style interface.  If an invalid command name is
passed, it will try to exec qmp-$1.

5) It attempts to pretty print the JSON responses in a shell friendly
format such that tools can work with the output.

Hope others will also find it useful.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Mark Wu <wudxw@linux.vnet.ibm.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2011-12-06 11:40:00 -02:00
..
qmp qmp: add test tool for QMP 2011-12-06 11:40:00 -02:00
qmp-events.txt fix spelling in QMP sub directory 2011-12-02 10:50:57 +00:00
qmp-shell QMP/qmp-shell: Introduce HMP mode 2010-11-17 09:52:24 -02:00
qmp-spec.txt QMP: Add "Downstream extension of QMP" to spec 2010-05-19 12:04:08 -03:00
qmp.py QMP: add server mode to QEMUMonitorProtocol 2011-06-01 11:43:18 -03:00
README QMP: Drop vm-info example script 2010-11-17 09:51:07 -02:00

                          QEMU Monitor Protocol
                          =====================

Introduction
-------------

The QEMU Monitor Protocol (QMP) allows applications to communicate with
QEMU's Monitor.

QMP is JSON[1] based and currently has the following features:

- Lightweight, text-based, easy to parse data format
- Asynchronous messages support (ie. events)
- Capabilities Negotiation

For detailed information on QMP's usage, please, refer to the following files:

o qmp-spec.txt      QEMU Monitor Protocol current specification
o qmp-commands.txt  QMP supported commands (auto-generated at build-time)
o qmp-events.txt    List of available asynchronous events

There is also a simple Python script called 'qmp-shell' available.

IMPORTANT: It's strongly recommended to read the 'Stability Considerations'
section in the qmp-commands.txt file before making any serious use of QMP.


[1] http://www.json.org

Usage
-----

To enable QMP, you need a QEMU monitor instance in "control mode". There are
two ways of doing this.

The simplest one is using the '-qmp' command-line option. The following
example makes QMP available on localhost port 4444:

  $ qemu [...] -qmp tcp:localhost:4444,server

However, in order to have more complex combinations, like multiple monitors,
the '-mon' command-line option should be used along with the '-chardev' one.
For instance, the following example creates one user monitor on stdio and one
QMP monitor on localhost port 4444.

   $ qemu [...] -chardev stdio,id=mon0 -mon chardev=mon0,mode=readline \
                -chardev socket,id=mon1,host=localhost,port=4444,server \
                -mon chardev=mon1,mode=control

Please, refer to QEMU's manpage for more information.

Simple Testing
--------------

To manually test QMP one can connect with telnet and issue commands by hand:

$ telnet localhost 4444
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
{"QMP": {"version": {"qemu": {"micro": 50, "minor": 13, "major": 0}, "package": ""}, "capabilities": []}}
{ "execute": "qmp_capabilities" }
{"return": {}}
{ "execute": "query-version" }
{"return": {"qemu": {"micro": 50, "minor": 13, "major": 0}, "package": ""}}

Development Process
-------------------

When changing QMP's interface (by adding new commands, events or modifying
existing ones) it's mandatory to update the relevant documentation, which is
one (or more) of the files listed in the 'Introduction' section*.

Also, it's strongly recommended to send the documentation patch first, before
doing any code change. This is so because:

  1. Avoids the code dictating the interface

  2. Review can improve your interface.  Letting that happen before
     you implement it can save you work.

* The qmp-commands.txt file is generated from the qmp-commands.hx one, which
  is the file that should be edited.

Homepage
--------

http://wiki.qemu.org/QMP