request as data source in transformation?

Dear XSLT forum, this is a teaser for an architectural kind of discussion,
not a syntax.

Rather than reference to external documents in XPath/ #XSLT, the
Declarative Web Application needs a concept of Request as valid data feed.

The data source reference the object is a result of transformation with
* url
* headers
* http method
* custom payload
* schema of data in response

This data source then could be used as input parameter for following XSLT
transformation via XPath. The data source is just a definition which would
be resolved to live HTTP request only when it is actually used in
transformation.

The request would produce the Response object with access to
* response HTTP code( 200 for normal, 4xxx, 5xxx errors, etc. )
* http headers
* data. The data reading would be immediate when no schema defined, or
triggered dynamically when data access needed by transformation/selectors
in case the schema is available.

-s
PS. The Declarative Web Application stack manifest and proposal is still in
baking and data access layer based on XSLT transformation pipeline is a
part of it.