## Package net.sf.saxon.trace

This package provides an interface to Saxon tracing and debugging capabilities.

See:
Description

Interface Summary
InstructionInfo: Information about an instruction in the stylesheet, made available at run-time to a TraceListener
InstructionInfoProvider: An InstructionInfoProvider is an object that is capable of providing an InstructionInfo object which provides diagnostic information about an instruction or other construct such as a function, template, expression, or pattern.
TraceListener: This interface defines methods that are called by Saxon during the execution of a stylesheet, if tracing is switched on.

Class Summary
AbstractTraceListener: This is the standard trace listener used when the -T option is specified on the command line.
Location: This class holds constants identifying different kinds of location in a source stylesheet or query.
TimedTraceListener: A Simple trace listener that writes messages to System.err
TraceEventMulticaster: A class which implements efficient and thread-safe multi-cast event dispatching for the TraceListener evants.
XQueryTraceListener: A Simple trace listener for XQuery that writes messages (by default) to System.err
XSLTTraceListener: A Simple trace listener for XSLT that writes messages (by default) to System.err

## Package net.sf.saxon.trace Description

This package provides an interface to Saxon tracing and debugging capabilities.

The package was originally created by Edwin Glaser.

The package includes three tracing modules that can be optionally selected: `XSLTTraceListener`, `XQueryTraceListener`, and `TimedTraceListener`. These all receive notification of the same events, but select and format the events in different ways to meet different requirements. Other events are notified through the `TraceListener` interface that are ignored by tracing applications, but may be of interest to debuggers.

Michael H. Kay
Saxonica Limited
9 February 2005