One of two interfaces that must be implemented to provide
a custom logging implementation.
The XSQL Page Processor asks the
XSQLLoggerFactory associated with
each request to create() an instance of an
XSQLLogger to service the current request. If the factory implementation
returns the same XSQLLogger instance to multiple requests, it needs
to worry about synchronizing access to the logger object as necessary.
Each page request has a unique XSQLPageRequest instance.
Returns a new or existing instance of XSQL logger. The XSQL page processing
engine will hold a reference to the XSQLLogger object returned by this
method for the duration of a single page request.