Actually this class implements a SAX filter for the
complete record OAI-PMH element. The contents of the header
child are collected into a header object and can be accessed by the
methods documented here.
Events will be traditionally forwarded only from the subelement(s) of
the metadata child which makes it difficult to access data
contained in the (possibly multiple) about containers which may follow
the metadata in the record.
Beginning from OAI-Harvester v1.20 a new recordHandler argument
may be given to the harvester functions getRecord() and listRecords():
In contrast to a metadataHandler argument this will pass the fwdAll
argument to the constructor of this Header class and result in
forwarding all events in the record (including record itself) to
the handler specified, not only those from metadata children.
In case of compatibility issues of Filters written for older veresions
you might set $Net::OAI::Harvester::OLDmetadataHandler = 1,
in which case the metadataHandler Option behaves like a recordHandler.
The SAX filter implemented by this class purposefully does not generate
any start_document() or end_document() events.
Consider inserting Net::OAI::Record::DocumentHelper as an additional
filtering stage if your handler(s) need these events, if they fail
class verification, or if you need a hook for capturing their result.