libxively C API frequently does nothing - xively

Question

I'm trying to use libxively to update my feed, but it frequently seems to do nothing. I've got a basic call:
{
xi_datastream_t& ds = mXIFeed.datastreams[2];
::xi_str_copy_untiln(ds.datastream_id, sizeof (ds.datastream_id), "cc-output-power", '\0');
xi_datapoint_t& dp = ds.datapoints[0];
ds.datapoint_count = 1;
::xi_set_value_f32(&dp, mChargeController->outputPower());
}
const xi_context_t* ctx = ::xi_nob_feed_update(mXIContext, &mXIFeed);
it logs the following:
[io/posix/posix_io_layer.c:182 (posix_io_layer_init)] [posix_io_layer_init]
[io/posix/posix_io_layer.c:191 (posix_io_layer_init)] Creating socket...
[io/posix/posix_io_layer.c:202 (posix_io_layer_init)] Socket creation [ok]
Once or twice I saw my Xively developer page show a GET feed, but otherwise, nothing seems to get written. Any suggestions on what I should look at?
I tried to rebuild the library using blocking calls (would be nice if nob didn't mean no blocking calls), but I couldn't figure out how to build it.
Thanks!
EDIT:
I was able to build a synchronous version of the library, and that seems to work. Can anyone verify that the async version works? Is there more to it than simply calling xi_nob_feed_update()?
EDIT 2:
I tried running the async example, but I'm doing something wrong, as it always complains of no data received:
$ bin/asynch_feed_update <my key> <my feed ID> example 1 example 4 example 20 example 58 example 11 example 17
example: 1 7
example: 4 7
example: 20 7
example: 58 7
example: 11 7
example: 17 7
[io/posix_asynch/posix_asynch_io_layer.c:165 (posix_asynch_io_layer_init)] [posix_io_layer_init]
[io/posix_asynch/posix_asynch_io_layer.c:174 (posix_asynch_io_layer_init)] Creating socket...
[io/posix_asynch/posix_asynch_io_layer.c:185 (posix_asynch_io_layer_init)] Setting socket non blocking behaviour...
[io/posix_asynch/posix_asynch_io_layer.c:203 (posix_asynch_io_layer_init)] Socket creation [ok]
No data within five seconds.

Answer 1

The asynchronous version should work. The xi_nob_feed_update() is the right function to make a feed update request.
You have to call process_xively_nob_step() in a loop just after select().
In general, you should follow the asynchronous example.