Hello, I have been looking for a technology which would allow me:

to validate a complex (large structure, many optional sub/sequences of elements, fixed order, etc.) XML;¶

to define custom error messages for each check/block of checks/rule (XSD processor-like errors are no use for me);¶

to define the validation schema/rules effectively and in a human readable way if possible;¶

In other words, something like Schematron (allows custom error msgs, is readable, etc.] but still elegant for complex structural checks (XPath is kind of inefficient for things like order checking and such).

I have discovered a XML2SCH project, although it seems to be a bit outdated and cumbersome for my use case.

Is there some suitable technology which would fit the needs I described? I could live with Schematron and (outdated) tools like XSD2SCH, although result of using these tools seems to be really behemothic.

Thanks