RE: Comprehensive list of issues with dereferencing a link?Stress-testin

["Costello, Roger L." <costello@mitre.org>]

Thank you very much for the outstanding responses.

I have a few questions about the behavior you expect of XML tools with respect to links (specifically, links to a redirect page).


1. Suppose an XML document has an external entity reference (link). The link points to a redirect page and the redirect page points to the real content. What behavior do you expect of an XML parser? Should the XML parser:

(a) Follow the redirect and retrieve the real content.

(b) Retrieve the redirect page.

(c) Generate an error.


2. Suppose an XML document is to be validated against an XML Schema. The schema validator is provided the link to the XML instance document and the link to the XML schema document. The link to the XML schema document points to a redirect page and the redirect page points to the real XML schema. What behavior do you expect of an XML schema validator? Should the XML schema validator:

(a) Follow the redirect and retrieve the real XML schema (and successfully validate against the real XML schema).

(b) Retrieve the redirect page and generate an error.

(c) Generate an error.


3. Suppose an XML document is to be transformed using an XSLT program. The XSLT processor is provided the link to the XML instance document and the link to the XSLT program. The link to the XSLT program points to a redirect page and the redirect page points to the real XSLT program. What behavior do you expect of an XSLT processor? Should the XSLT processor:

(a) Follow the redirect and retrieve the real XSLT program (and successfully transform using the real XSLT program).

(b) Retrieve the redirect page and generate an error.

(c) Generate an error.


4. Suppose an XML document is to be validated against an XML Schema which contains an xs:import element with a link to a schema document. The schema validator is provided the link to the XML instance document and the link to the XML schema document. The link to the imported XML schema document points to a redirect page and the redirect page points to the real imported XML schema. What behavior do you expect of an XML schema validator? Upon encountering the import link should the XML schema validator:

(a) Follow the redirect and retrieve the real imported XML schema (and successfully validate against the real imported XML schema).

(b) Retrieve the redirect page and generate an error.

(c) Generate an error.


5. Suppose an XML document is to be transformed using an XSLT program which contains an xsl:import element with a link to an XSLT document. The XSLT processor is provided the link to the XML instance document and the link to the XSLT program. The link to the imported XSLT program points to a redirect page and the redirect page points to the real XSLT program. What behavior do you expect of an XSLT processor? Upon encountering the import link should the XSLT processor:

(a) Follow the redirect and retrieve the real XSLT program (and successfully transform using the real imported XSLT program).

(b) Retrieve the redirect page and generate an error.

(c) Generate an error.


Have you tried any of these? Today I tried (2) -- validate an XML document against a schema. The validator did _not_ follow the redirect to the real XML schema document. The validator generated an error. That's not the behavior I expected.


/Roger