25. A computer-readable volatile or non-volatile medium storing one or more sequences of instructions which, when executed by one or more processors, cause the one or more processors to perform the steps of: after an XML processor, which is configured to send validated XML data to an application, starts performing a validation operation on an XML-based input stream, and before said XML processor completes performing said validation operation on said XML-based input stream, performing the steps of: after starting to validate a particular XML element in said XML-based input stream, and before completion of validating said particular XML element in said XML-based input stream, performing the computer-implemented step of said XML processor receiving one or more requests for particular information relating to said validation operation, wherein said one or more requests include at least one of: (a) a request for whether said particular XML element is defined in corresponding information that dictates the structure of said XML data in said XML-based input stream; (b) a request for the name of said particular XML element; (c) a request for the data type of said particular XML element; (d) a request for whether said particular XML element conforms to the corresponding information that dictates the structure of said XML data in said XML-based input stream; (e) a request for the current validation mode of said validation operation; (f) a request for the current state of said validation operation; or (g) a request for one or more annotations that are associated with said particular XML element; said XML processor generating one or more messages that include said particular information; and said XML processor responding to said one or more requests for said particular information by providing said one or more messages.
25. A computer-readable volatile or non-volatile medium storing one or more sequences of instructions which, when executed by one or more processors, cause the one or more processors to perform the steps of: after an XML processor, which is configured to send validated XML data to an application, starts performing a validation operation on an XML-based input stream, and before said XML processor completes performing said validation operation on said XML-based input stream, performing the steps of: after starting to validate a particular XML element in said XML-based input stream, and before completion of validating said particular XML element in said XML-based input stream, performing the computer-implemented step of said XML processor receiving one or more requests for particular information relating to said validation operation, wherein said one or more requests include at least one of: (a) a request for whether said particular XML element is defined in corresponding information that dictates the structure of said XML data in said XML-based input stream; (b) a request for the name of said particular XML element; (c) a request for the data type of said particular XML element; (d) a request for whether said particular XML element conforms to the corresponding information that dictates the structure of said XML data in said XML-based input stream; (e) a request for the current validation mode of said validation operation; (f) a request for the current state of said validation operation; or (g) a request for one or more annotations that are associated with said particular XML element; said XML processor generating one or more messages that include said particular information; and said XML processor responding to said one or more requests for said particular information by providing said one or more messages. 43. The computer-readable volatile or non-volatile medium of claim 25 , wherein the one or more sequences of instructions further comprise instructions which, when executed by the one or more processors, cause the one or more processors to perform the step of: reading said one or more annotations from metadata that corresponds to said XML-based input stream.