[Exist-open] Error handling in the web application

[that.SelectedDude <tha...@gm...>]

Hi, I'm writing some .xql files within eXist's web application.

When a static error (i.e., on compiling a .xql file) occurs, it gets thrown.
However, dynamic errors aren't (Jetty will output a standard "HTTP 500"
error message only).
 
I would like to have each error either being thrown or logged.
 
I was looking into the various log files (in /webapp/WEB-INF/logs,
/tools/jetty/logs, and /tools/wrapper/logs) and config files (in /,
/tools/jetty/etc, /tools/wrapper/conf, and /webapp/WEB-INF), but I don't
understand the logging mechanisms ^^completely.
 
In /tools/jetty/etc/jetty.xml there is an option that looks promising,
-----------------------------------------------------------
  <!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -->
  <!-- Configure Jetty Logging.                                        -->
  <!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -->
  <!-- Uncomment if using jetty logging.
  <Call class="org.apache.commons.logging.LogFactory" name="getFactory">
    <Call name="getInstance">
      <Arg/>
      <Call name="reset"/>
      <Call name="add">
        <Arg>
          <New class="org.mortbay.log.OutputStreamLogSink">
            <Set name="filename"><SystemProperty name="jetty.home"
default="."/>/logs/yyyy_mm_dd.jetty.log</Set>
            <Set name="retainDays">90</Set>
            <Set name="append">true</Set>
            <Set name="logLabels">true</Set>
            <Set name="logStackSize">true</Set>
            <Set name="logStackTrace">false</Set>
            <Set name="logOneLine">false</Set>
            <Set name="suppressStack">false</Set>
            <Set name="logTimeZone">GMT</Set>
          </New>
        </Arg>
      </Call>
    </Call>
  </Call>
  -->
-----------------------------------------------------------
however, when I uncomment it and restart eXist, Jetty won't start, and
/tools/wrapper/logs/exist.log reports:
-----------------------------------------------------------
2006-10-23 18:36:45,369 [WrapperListener_start_runner] DEBUG
(XmlConfiguration.java [call]:522) - call getFactory
2006-10-23 18:36:45,369 [WrapperListener_start_runner] DEBUG
(XmlConfiguration.java [call]:522) - call getInstance
2006-10-23 18:36:45,385 [WrapperListener_start_runner] WARN  (Server.java
[<init>]:111) - EXCEPTION java.lang.reflect.InvocationTargetException
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at org.mortbay.xml.XmlConfiguration.call(XmlConfiguration.java:539)
	at
org.mortbay.xml.XmlConfiguration.configure(XmlConfiguration.java:252)
	at org.mortbay.xml.XmlConfiguration.call(XmlConfiguration.java:546)
	at
org.mortbay.xml.XmlConfiguration.configure(XmlConfiguration.java:252)
	at
org.mortbay.xml.XmlConfiguration.configure(XmlConfiguration.java:184)
	at org.mortbay.jetty.Server.<init>(Server.java:103)
	at org.mortbay.jetty.Server.<init>(Server.java:77)
	at org.exist.JettyStart.run(JettyStart.java:108)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at org.exist.wrapper.Main.start(Main.java:85)
	at
org.tanukisoftware.wrapper.WrapperManager$12.run(WrapperManager.java:2788)
Caused by: java.lang.NullPointerException
	at
org.apache.commons.logging.impl.LogFactoryImpl.getInstance(LogFactoryImpl.ja
va:209)
	... 18 more
----------------------------------------------------------

That's strange as the Jetty log config looks like it should work righton.

- Anyone to shed some light on how to handle errors by either throwing or
logging them?

Thanks
Robert