[Summary] Big hierarchy of XML Schema documents ... which XML Schema validators bring in the documents on demand?

Hi Folks,

Thanks to Michael Glavassevich, Michael Kay, and Boris Kolpackov for your excellent inputs.

Here's what I learned (please correct any errors):

Suppose that your XML Schema imports/includes some XML Schemas, and they import/include some XML Schemas, and so on. Thus, there is a big hierarchy of XML Schema documents.

When does a validator read the XML Schema documents? Here are two ways that XML Schema validators could be implemented:

1. Just-in-time loading (a.k.a. on-demand loading): the validator reads an XML Schema document during instance validation, when a component from the relevant namespace is first encountered.

2. Eager loading: all XML Schema documents are (recursively) read prior to validating the XML instance document.

The following XML Schema validators all use eager loading:

    SAXON (Java)

    SAXON (.NET)

    XERCES (Java)

    XERCES (C++)

    XERCES (Perl)

    LIBXML (Gnome's libxml2)

    MSXML

    XSV


/Roger