Hessian servlet debugging is enabled in a two-step process. First, the "debug" init-param must be set in the web.xml. Second, the java.util.logging level for com.caucho.hessian.servlet must be set to "fine". The configuration in a Resin server might look like the following:

resin-web.xml enabling debugging

<web-app xmlns="http://caucho.com/ns/resin">

  <servlet-mapping url-pattern="/my-bean"
                   servlet-class="example.MyBean">
    <init debug="true"/>
  </servlet-mapping>

  <log name="com.caucho.hessian.server" level="fine"
          path="stdout:"/>

</web-app>

The output might look like the following:

sample debugging output

public class MyBean extends HessianServlet {
  public example.Combine combine(String a, String b)
}


[2007/05/08 02:51:31.000] call 2.0
[2007/05/08 02:51:31.000]   method "combine"
[2007/05/08 02:51:31.000]   "hello"
[2007/05/08 02:51:31.000]   "world"
[2007/05/08 02:51:31.000] reply 2.0
[2007/05/08 02:51:31.000]   /* defun example.Combine [a, b] */
[2007/05/08 02:51:31.000]   object example.Combine (#1)
[2007/05/08 02:51:31.000]     a: "hello"
[2007/05/08 02:51:31.000]     b: "world"

Serialized Hessian

Hessian provides two debugging streams to debug any input or output stream, HessianDebugInputStream and HessianDebugOutputStream. They can be used as follows:

HessianDebugInputStream

import com.caucho.hessian.io.*;

...

void test(PrintWriter dbg, String filename)
  throws IOException
{
  FileInputStream is = new FileInputStream(filename);

  HessianDebugInputStream in;
  in = new HessianDebugInputStream(is, dbg);

  int ch;
  while ((ch = in.read()) >= 0) {
  }
}