On Tue, Dec 06, 2011 at 02:58:59PM +0200, Dan Kenigsberg wrote:
On Mon, Dec 05, 2011 at 11:34:18AM -0600, Adam Litke wrote:
Hi everyone. On today's VDSM call we discussed the requirements, design, and plan for updating the API to include support for QMF and single-host REST API. All members present arrived at a general consensus on the best way to design the next-generation API. I have tried to capture this discussion in the oVirt wiki:
http://ovirt.org/wiki/Vdsm_API
Please take a look at this page and let's discuss any changes that may be needed in order to adopt it as a working plan that we can begin to execute. Thanks!
Very nice, I've fixed two bullets about the future of the xml-rpc.
Thanks... Updates look good to me.
I think that we are missing something here: how do we model Vdsm-to-Vdsm communication, in a binding-blind way? I'm less worried about the storage-based mailbox used for lvextend requests: my problem is with migration command.
Ok, interesting... Besides migration, are there other features (current or planned) that would involve P2P communication? I want to ensure we consider the full problem space.
Currently, the implementation of the "migrate" verb includes contacting the remote Vdsm over xml-rpc before issuing the libvirt migrateToURI2 command ('migrationCreate' verb).
A Vdsm user who choose to use the REST binding, is likely to want this to be implemented this using a REST request to the destination. This means that the implementation of Vdsm depends on the chosen binding.
The issue can be mitigating by requiring the binding level to provide a "callback" for migrationCreate (and any other future Vdsm->world requests). This would complicate the beautiful png at http://ovirt.org/wiki/Vdsm_API#Design ... Does anyone have another suggestion?
Actually, I think you are blending the external API with vdsm internals. As a management server or ovirt-engine, I don't care about the protocol that vdsm uses to contact the migration recipient. As far as I am concerned this is a special case internal function call. For that purpose, I think xmlrpc is perfectly well-suited to the task and should be used unconditionally, regardless of the bindings used to initiate the migration. So I would propose that we modify the design such that we keep an extremely thin xmlrpc server active whose sole purpose is to service internal P2P requests. -- Adam Litke <agl@us.ibm.com> IBM Linux Technology Center