# Logging Debug Messages and Exceptions

During run time, the Http control checks for different parameters, null value, and method return types. If validation fails at any point, a control exception is thrown to the Business Process Management (BPM). You can log debug messages, review them, and resolve exceptions if required.

To log debug messages, edit the WebLogic Workshop log properties file. You can find the workshop log properties file, workshopLogCfg.xml, in the WL_HOME\weblogic81\common\lib\ folder.

To log all the debug statements for HttpControlImpl and HttpResource class files, add the following lines to the workshopLogCfg.xml file:

    <category name="com.bea.control.HttpControl">
    <!-- NOTE: DO NOT CHANGE THIS PRIORITY LEVEL W/O WLI DEV APPROVAL -->
    <!-- Debug-level log information is frequently the only tool available to
    diagnose failures! -->
    <priority value="debug"/>
    <appender-ref ref="SYSLOGFILE"/>
    <appender-ref ref="SYSERRORLOGFILE"/>
    </category>
    <category name="com.bea.control.HttpResource">
    <!-- NOTE: DO NOT CHANGE THIS PRIORITY LEVEL W/O WLI DEV APPROVAL -->
    <!-- Debug-level log information is frequently the only tool available to
    diagnose failures! -->
    <priority value="debug"/>
    <appender-ref ref="SYSLOGFILE"/>
    <appender-ref ref="SYSERRORLOGFILE" />
    </category>

All debug statements are logged into workshop_debug.log file in the corresponding domain where the application runs.

## Http Control Caveats

The following are the known limitations of the Http control:

- The Http control doesn't expose any specific method for posting a multi-part document. However, you can write the code to construct a multi-part message and then convert it into byte stream and use the sendDataAsHttpPost(byte[] bodyData) method to post data.
- The Http control does not support Microsoft Proxy Server. This is because Microsoft Proxy Server uses NT Lan Manager (NTLM) authentication, which is proprietary to Microsoft.