dipal and WS-Agreement

Colleagues,

To restart the discussion for this new year, I would like to suggest 
that DIPAL would be an ideal assertion/condition expression language for 
use with the WS-Agreement specification being developed in the Global 
Grid Forum Grid Resource Allocation and Agreement Protocol WG 
(http://www.ggf.org/Public_Comment_Docs/Documents/Oct-2005/WS-AgreementSpecificationDraft050920.pdf).

The WS-Agreement specification specifically says that WS-Agreement will 
use condition expression languages defined by other standards groups. 
They mention XQuery as an example of such a language, but XQuery has the 
disadvantage of not having a well-defined condition intersection 
function: if two agreements contain conditions over the same 
variable/schema element expressed using XQuery, it is not possible to 
determine automatically whether the two conditions are compatible or 
what their intersection is (i.e. what XQuery expression would satisfy 
both agreement conditions).  The condition functions defined in 
WS-PolicyConstraints, however, have completely defined, efficient 
intersection algorithms.

Opinions?  Other ideas about how DIPAL might fit into other proposed 
standards?

Regards,
Anne
-- 
Anne H. Anderson               
Sun Microsystems Labs          1-781-442-0928
Burlington, MA USA