When use mtom to transfer one file, server log shows the file is accessed twice.

[Jeffery Yuan]

Hi, all:
I found out that when I use jax-ws mtom to transfer file, the server log shows that the file is accessed twice - I tested the sample in both glassfish and jboss server.

The test code is like this:

Web service code:

package org.example.ws.service;
@WebService(serviceName = "GetContentService", targetNamespace = "http://ws.example.org/")
@MTOM(enabled=true, threshold=0)
public class GetContentService {
    @WebMethod(operationName = "getStuff")
    public ReturnObject getStuff() {
        ReturnObject rtno = new ReturnObject();
        String sURL = "http://localhost:8080/file";
        URL myurl;
        try {
            myurl = new URL(sURL);
            URLDataSource urlds = new URLDataSource(myurl);
            DataHandler datahandler = new DataHandler(urlds);
            rtno.sURL = sURL;
            rtno.content = datahandler;
        } catch (MalformedURLException e) {
            e.printStackTrace();
        }
        return rtno;
    }
}
@XmlType(name = "ReturnObject", namespace = "http://ws.example.org/")
@XmlAccessorType(XmlAccessType.FIELD)
public class ReturnObject {
    public String sURL;
    @XmlMimeType("application/octet-stream")
    public DataHandler content;
}

Web service client code:

package example.ws.client;
import javax.xml.ws.soap.SOAPBinding;
public class TestGetContentService {
    public static void main(String[] args) throws Exception {
        InputStream is = null;
        try {
            ReturnObject ro = getStuff();
            DataHandler dh = ro.getContent();
            byte[] buffer = new byte[1024];
            int size = 0, total = 0;
            is = dh.getInputStream();
            while ((size = is.read(buffer)) > 0) {
                total += size;
            }
            System.out.println("total size = " + total);
        } catch (IOException ex) {
            ex.printStackTrace();
        }
    }
    private static ReturnObject getStuff() {
        GetContentService_Service service = new GetContentService_Service();
        GetContentService port = service.getGetContentServicePort(new MTOMFeature());
        BindingProvider bp = (BindingProvider) port;
        SOAPBinding binding = (SOAPBinding) bp.getBinding();
        binding.setMTOMEnabled(true);
        return port.getStuff();
    }
}

When I try to get one small file, about 2 kb, the following line would be recorded in localhost_access_log:
127.0.0.1 - - [03/Nov/2011:15:04:49 +0800] "GET /file HTTP/1.1" 200 1748
127.0.0.1 - - [03/Nov/2011:15:04:49 +0800] "GET /file HTTP/1.1" 200 1748
===> accessed twice.
10.32.98.213 - - [03/Nov/2011:15:04:49 +0800] "POST /example-ws/GetContentService HTTP/1.1" 200 25700

When I try to get one big file - 3074 k, the following line would be recorded in localhost_access_log:
127.0.0.1 - - [03/Nov/2011:15:10:38 +0800] "GET /file HTTP/1.1" 200 3147690
10.32.98.213 - - [03/Nov/2011:15:10:38 +0800] "POST /example-ws/GetContentService HTTP/1.1" 200 3148515
127.0.0.1 - - [03/Nov/2011:15:10:42 +0800] "GET /file HTTP/1.1" 200 40960
=====> accessed twisce, but the size of the get request is much smaller.

This should be related how mtom and datahandler is implemented in jax-ws.
I am wondering why the file is accessed twice, and is this expected behavior or not?