Indicating element nodes that must be optimized with XOP

This is a proposal for a xop:optimize attribute which should address
the issue Glen referred to yesterday, and at the bottom it contains
two comments that I think we want to send to the XML Protocol WG.

As we have seen at our last F2F meeting, we can indicate that MTOM is
in use as shown in Glen's message[6].

The issue we have left as we discussed yesterday in our telcon is to
identify which elements node to be optimized as per step 4 of the XOP
processing model[7].

I believe that, if I'm using XOP and I'm the sender of a message, I
can optimize any base64 element node I want. From this point of view,
we don't need to indicate which nodes need to be optimized.

However, a service may want to indicate that it wants the HTTP
Transmission Optimization Feature to be used, and that the content of
a particular element (e.g. a large Base64-encoded image) must be
optimized.

I believe that we can achieve this by simply defining a xop:optimize
attribute that can be stuck on the elements of type xs:base64Binary
when defining the message formats.

The values of xop:optimize could be false or true, true meaning that
if a XOP is used, e.g. with the HTTP Transmission Optimization
Feature, the element node must be optimized, false being the default
value and leaving it up to the sender to decide whether to optimize or
not an element node.

An interesting thing I realized is that XOP itself is not a feature,
i.e. the HTTP Transmission Optimization Feature uses XOP (which is
only specific to SOAP despite its name) but doesn't say it's using the
XOP feature, with a URI, etc.

It would be cool to have the HTTP Transmission Optimization Feature
say that it uses the XOP feature, and then if somebody defines the XML
over HTTP Transmission Optimization Mechanism feature as per my
previous email[8], the feature could say that it uses the XOP feature
and then it would be clear when the xop:optimize attribute becomes
relevant.

I guess that these are two comments that we should send to the XML
Protocol Working Group: use a less general, more SOAP-tied, name for
the feature, and make XOP a feature so that it has a URI and we know
when it's used.

Regards,

Hugo

  6. http://lists.w3.org/Archives/Public/www-ws-desc/2004May/0077.html
  7. http://www.w3.org/TR/2004/WD-xop10-20040209/#xop_processing_model
  8. http://lists.w3.org/Archives/Public/www-ws-desc/2004May/0088.html
-- 
Hugo Haas - W3C
mailto:hugo@w3.org - http://www.w3.org/People/Hugo/