processing run anymore. The log output of multiple, simultaneously running FOP instances
is sent to the same logger.
</p>
- <note>
- We know this may be an issue in multi-threaded server environments if you'd like to
- know what's going on in every single FOP processing run. We're planning to add an
- additional feedback facility to FOP which can be used to obtain all sorts of specific
- feedback (validation messages, layout problems etc.). "Static logging" is mainly
- interesting for a developer working on FOP and for advanced users who are debugging
- FOP. We don't consider the logging output to be useful to normal FOP users. Please
- have some patience until we can add this feature or jump in and help us build it. We've
- set up a <a href="http://wiki.apache.org/xmlgraphics-fop/ProcessingFeedback">Wiki page</a>
- which documents what we're going to build.
- </note>
<p>
By default, <a href="ext:commons-logging">Jakarta Commons Logging</a> uses
JDK logging (available in JDKs 1.4 or higher) as its backend. You can configure Commons
<a href="ext:commons-logging">documentation for Jakarta Commons Logging</a> on
how to configure alternative backends.
</p>
+ <p>
+ As a result of the above we differentiate between to kinds of "logging":
+ </p>
+ <ul>
+ <li>(FOP-)Developer-oriented logging</li>
+ <li><a href="events.html">User/Integrator-oriented feedback</a> (NEW!)</li>
+ </ul>
+ <p>
+ The use of "feedback" instead of "logging" is intentional. Most people were using
+ log output as a means to get feedback from events within FOP. Therefore, FOP now
+ includes an <code>event</code> package which can be used to receive feedback from
+ the layout engine and other components within FOP <strong>per rendering run</strong>.
+ This feedback is not just some
+ text but event objects with parameters so these events can be interpreted by code.
+ Of course, there is a facility to turn these events into normal human-readable
+ messages. For details, please read on on the <a href="events.html">Events page</a>.
+ This leaves normal logging to be mostly a thing used by the FOP developers
+ although anyone can surely activate certain logging categories but the feedback
+ from the loggers won't be separated by processing runs. If this is required,
+ the <a href="events.html">Events subsystem</a> is the right approach.
+ </p>
</section>
<section id="render">