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 Resin Server | Application Server (Java EE Certified) and Web Server


Hessian provides debugging tools to view the wire protocol or serialized Hessian data.

Debugging requires Hessian 3.1.3 or later.

Debugging HessianServlet

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="">

  <servlet-mapping url-pattern="/my-bean"
    <init debug="true"/>

  <log name="com.caucho.hessian.server" level="fine"


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:



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

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

  int ch;
  while ((ch = >= 0) {

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