RE: uri templates: escaping & defaults

Roy T. Fielding wrote:
> On Jul 13, 2011, at 9:19 AM, Manger, James H wrote:
> > 6.
> > There are no examples with defaults for more than 1 variable.
> > For example, add "x{/var|1st,empty|2nd}" to section 2.5
> > "Value Defaults". The very long list of examples in this
> > section is not good sign to me that this feature's design
> > is intuitive.
> 
> Right.  The reason is simply that the examples get too long.
> 
> Anyway, I was thinking about defaults this morning and realized that
> I don't have any use case for them.  That is, if we assume that the
> server is telling the client what values are to okay to place in the
> variables, then why would the server ever tell the client that the
> variable is undefined?
> 
> The only use case that I know of is that it allows the server to
> state what parts of the URI space are never empty.  However, I can't
> think of anyone who needs that.  Are there other use cases?

I've seen (and written) plenty of API's where /foos/bar/baz makes sense
but /foos//baz doesn't make sense (at best, or breaks at worst). It
would be useful to be able to write something like /foos/{bar!}/baz
where the "!" character constrains the value to be supplied and not
empty.


Robert Brewer
fumanchu@aminus.org