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Re: [Qemu-devel] [RFC][PATCH v5 00/21] virtagent: host/guest RPC communi
Re: [Qemu-devel] [RFC][PATCH v5 00/21] virtagent: host/guest RPC communication agent
Fri, 10 Dec 2010 09:42:45 +0000
On Thu, Dec 9, 2010 at 9:03 PM, Anthony Liguori
> On 12/09/2010 02:45 PM, Michael Roth wrote:
>> On 12/08/2010 04:10 AM, Stefan Hajnoczi wrote:
>>> On Fri, Dec 3, 2010 at 6:03 PM, Michael Roth<address@hidden>
>>>> These patches apply to master, and can also be obtained from:
>>>> git://repo.or.cz/qemu/mdroth.git virtagent_v5
>>> Why XML-RPC and not QMP? When I skim through the patch series it
>>> seems like much of the work being done is very similar to QMP.
>> It does, actually, more than I realized. In terms of data encapsulation I
>> don't see why we couldn't use QMP/JSON for at least the current set of RPCs.
>> XMLRPC does support a wider range of data types however, such as nestable
>> arrays and structs, and set-precision numerical types like 32 and 64-bit
>> ints/floats, which may prove useful for future lower level interfaces.
> 1) XML-RPC is more widely supported than QMP (as there is zero support for
> QMP outside of QEMU and libvirt)
True, but the current design doesn't lend itself to custom agents at
the XML-RPC level. Therefore using a standard protocol doesn't win
anything - it would have been more useful for QMP actually.
> 2) The target of this work is for guest agents
Not sure what this means.
> 3) QMP does not support bidirectional RPC messages.
Right. QMP has commands, responses, and asynchronous events so the
client and server are two different roles (asymmetric).
I hadn't though through the details and this suggests shoehorning QMP
in as the agent protocol would be ugly.
> 4) The RPC mechanism is a minor part of virt-agent so ultimately, it kind of
> doesn't matter. The RPC messages themselves are what's important.
Getting the design and features of virtagent right is key. But we
still need to maintain the code, that's why I ask about reusing what
- [Qemu-devel] Re: [RFC][PATCH v5 20/21] virtagent: integrate virtagent server/client via chardev, (continued)
- [Qemu-devel] [RFC][PATCH v5 15/21] virtagent: add agent_capabilities qmp/hmp commands, Michael Roth, 2010/12/03
- [Qemu-devel] [RFC][PATCH v5 16/21] virtagent: add client capabilities init function, Michael Roth, 2010/12/03
- [Qemu-devel] [RFC][PATCH v5 10/21] virtagent: add agent_viewdmesg qmp/hmp commands, Michael Roth, 2010/12/03
- [Qemu-devel] [RFC][PATCH v5 21/21] virtagent: various bits to build QEMU with virtagent, Michael Roth, 2010/12/03
- [Qemu-devel] Re: [RFC][PATCH v5 00/21] virtagent: host/guest RPC communication agent, Jes Sorensen, 2010/12/07
- Re: [Qemu-devel] [RFC][PATCH v5 00/21] virtagent: host/guest RPC communication agent, Stefan Hajnoczi, 2010/12/08