[Gestalt-users] Design and use-cases for web-services access

[Colin A. <col...@ho...>]

This is principally addressed to Abel, as he has expressed a wish for the 
functionality, but others may well be interested too.

It is currently possible to do an HTTP(S) POST followed by an HTTP(S) GET by 
following a call to xsl:result-document by one to fn:document(), but with 
the proviso that the two URIs differ in some respect (such as a query 
parameter) other than a fragment identifier.

This might work in any XSLT 2.0 processor (but since it has an intrinsic 
dependency on the order of processing, it cannot be relied upon), but last 
time I tested http with xsl:result-document in Saxon, it did not work. It 
does work with Gestalt, but since a long-term goal for Gestalt is to using 
parallel processing, it cannot be relied upon to work forever.

Still, this is an interesting (but rather limiting) use case.

Abel, can you set up a web server which can be used to test such a use case, 
write a transformation to verify that it works, and publish it here? It will 
be a good regression test, to make sure the full scheme doesn't break this 
case.

It will not be hard to modify xsl:result-document to return a document node 
from an HTTP(S) POST, but as the XSLT REC specifies the value of the 
xsl:result-document instruction is an empty sequence, this cannot be done.

So my suggested solution is an extension instruction in the namespace 
http://gestalt.sourceforge.net/extension
local name of result-document,
which is identical in it's semantics to xsl:result-document, except that the 
result of evaluating it is zero or one document nodes.

Then the result of a SOAP request (for instance) can be captured in an 
xsl:variable by placing a gestalt:result-document instruction into its 
sequence constructor.

Any comments on this design?

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