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However, this is not quite enough, as the user is likely to want to route this hexBinary data blob somewhere, and capture the diagnostic information from the parse failure to keep with it. The normal behavior of a choice where a second alternative succeeds would be to discard error/diagnostic information from any prior failing alternative. Hence, a top-level API is needed which provides access to the failure diagnostic information for the overall parse. Consistent with discussion herein about lazy message construction, the blob of binary data needed for a diagnostic should really be an offset and length into some data stream. The data blob itself can be large, but we should only copy it if this is required.
Gathering Multiple Compile-Time Errors
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Applications that embed Daffodil are very likely to be servers, so a target logger to which Daffodil writes out logging/tracing needs to be something that the application can provide to Daffodil via an API like a setLogger() function.
In the case of an interactive DFDL Schema authoring environment, trace information would normally be displayed to the user/author. A runtime server that embeds Daffodil would more likely want to log to a file-system-based logger, and possibly trigger alerts flowing to a monitoring system of some kind.
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