Re: [Libvir] XML-RPC support for libvirt

Howdy,

I'm about to checkin some XML-RPC code into CVS. The code I'm checking

in won't compile by default (for now) as there's still a little work to do but I wanted to get something into the tree. Here are the tasks left: 1) Convert from dict to s-expressions to handle config returns. Right now, the Xend XML-RPC code returns S-Expressions in the form of a tuple. We just need a little code to convert from these tuples to struct sexpr's. 2) Integrate my unit tests. I've got a number of unit tests that stress the various bits of parsing code. I'd like to add a make check that runs these unit tests and a make fullcheck that runs these unit tests under valgrind. 3) Support XML-RPC over a domain socket. Right now I'm using nanohttp which doesn't appear to allow different transports. There is some HTTP PUT code already in the tree so I could use that if there isn't a more clever solution. 4) Plumb the xend backend functions to XML-RPC. This is really straight forward. It's just a matter of converting: int xend_pause(virConnectPtr xend, const char *name) { return xend_op(xend, name, "op", "pause", NULL); } To: int xend_pause(virConnectPtr xend, const char *name) { if (xend->xmlrpc) return xmlRpcCall(xend->xmlrpc, "xend.domain.pause", "", "s", name) else return xend_op(xend, name, "op", "pause", NULL); }

Of course, using the xml-rpc code, we now have access to rich fault information. Xend never actually returns errors for things and instead throws exceptions.

For the S-Expression/HTTP protocol, you just get a 501 and have to return a meaningless error. With XML-RPC, those exceptions are actually serialized and sent over the wire. We may want to explore how we can make that information available to the user.

My current understanding, btw, is that the basic XML-RPC support for Xend is going into the tree sometime this week (Ewan is looking at the code now) and will be a part of the 3.0.2 release. This means that for

the 3.0.3 cycle, we'll be defining a standard API. This process will be starting soon (within the next couple of weeks hopefully).