Minimizing the processing on the proxy resolver invoker.

["Steven Churchill" <steven.churchill@xdi.org>]

Drummond,

Regarding yesterday's change regarding the proxy resolver's output, we
should do our best to minimize redundant processing on the part of the proxy
invoker.

For example, I suggest that the XRD (for _xrd_r = "xrd") be output in such a
way as to allow the invoker to use a simple/fast function such as:

   // For example, s.between("foo", "baz") returns "bar" in "foobarbaz"
   String between(String this, String that); 

in order to, say, pull out the selected service's highest priority URI. For
example, allow the invoker to do something like this to get the URI:
 
   String highestPriorityURI = xrd.between("URI>", "<");


In order to support this, we'd need to specify some requirements on the
output <XRD>:

1.	The selected service is the first in the list.
2.	The highest priority URI is the first in that list.
3.	The <URI> has no attributes. This way we can say xrd.between("URI>".

4.	The highest priority CanonicalID is the first in it's list.
5.	The CanonicalID has no priority.

The converse to this proposal (not doing something like this) seems a bit
strange to me. That is, because we have the information at hand in the
Resolver, it's as though we'd intentionally be obfuscating it before
returning it to the invoker.

Thoughts?

~ Steve