Problem sending XML via HTTP

Question

I want to have an application which parses various RSS feeds and send the information to a remote server. The information is sent in xml format via http. At first I tried to deploy this application on my own server, so I send the xml using the method shown in this tutorial by Java Tips. Here is my code which is replicated from the example:

First Method

    String strURL = "http://localhost/readme/readme_xml";
    String strXMLFilename = "output.xml";
    File input = new File(strXMLFilename);


    PostMethod post = new PostMethod(strURL);
    post.setRequestEntity(new InputStreamRequestEntity(
            new FileInputStream(input), input.length()));
    post.setRequestHeader(
            "Content-type", "text/xml; charset=ISO-8859-1");
    HttpClient httpclient = new HttpClient();
    try {

        int result = httpclient.executeMethod(post);            
        System.out.println("Response status code: " + result);            
        System.out.println("Response body: ");
        System.out.println(post.getResponseBodyAsString());            
    } finally {
        post.releaseConnection();
    }

This works perfectly (I even tested using a remote server outside the localhost). Then, somehow I cant use my own server to deploy this application, so I decided to migrate to Google Apps Engine. One thing about it, as we know it, is that not all libraries are allowed in the environment. So I try another method shown in ExampleDepot.com (I can't find where the exact url though) as below:

Second Method

try {
           /* fill up this url with the remote server url */
            URL url = new URL("http://localhost/readme/readme_xml");
            FileReader fr = new FileReader("output.xml");
            char[] buffer = new char[1024*10];
            int len = 0;
            if ((len = fr.read(buffer)) != -1){
            /* send http request to remote server */
                URLConnection conn = url.openConnection();
                conn.setRequestProperty("Content-Type","text/xml;charset=ISO-8859-1"); /* need to specify the content type */
                conn.setDoOutput(true);
                conn.setDoOutput(true);
                PrintWriter pw = new PrintWriter(conn.getOutputStream());
                pw.write(buffer, 0, len);
                pw.flush();
                /* receive response from remote server*/
                BufferedReader bf = new BufferedReader(new InputStreamReader(conn.getInputStream()));
                String input = null;
                while ((input = bf.readLine()) != null){
                    System.out.println(input);
                }
            }

        } catch (MalformedURLException e) {
                e.printStackTrace();
        } catch (FileNotFoundException e) {
                e.printStackTrace();
        } catch (IOException e) {
                e.printStackTrace();
        }
    }

The second method though, doesn't work and gives the following error (I use SimpleXMLElement (php) object to parse xml in the remote hosting):

Error message from remote server

Here's the php code from the remote server (In here, I just want the SimpleXMLElement to parse the xml without doing anything else fancy for now)

$xml = new SimpleXMLElement('php://input', NULL, TRUE);
   foreach ($xml -> attributes() as $name => $val){
   echo "[".$name."] = ".$val."\n";
   }

I thought the cause of this problem is the malfunction xml file (because the eclipse IDE indicates there's error of "invalid byte 1 of 1-byte utf-8 sequence"). Then I use the same exact input xml file to the first method, but it still works perfectly.

So is there any adjustment that I need to make to the second method? Or is there any other method that I can use to send xml file to remote server? Let me know if I need to add some other details. Thanks for your help.

---

NOTE: I actually solved this problem by using the solution given in the comments. I didn't use approaches suggested in the answers, even though those answers are pretty useful. So, I didn't select the best answer out of those answers given. Nonetheless, I still appreciate all of your helps, thus deserve my upvote. Cheers!

Answer 1

I guess you need to change the content type to multipart/form-data. See an already answered question in detailed. The file upload is discussed at the bottom of this example

Answer 2

I would, as the first answer suggest, read the file with an InputStream. Converting from byte to char and back again is unnecessary and a source of error. Also, verify that the input file really is using the ISO-8859-1 encoding.

UPDATE:

When using a FileReader, you accept the default encoding (i.e. how to make chars from bytes). This encoding must match the encoding used for the input file, otherwise there's a great risk that the result is corrupted. The default Java encoding is different for different platforms, so it is generally not a good idea to rely on it.

In your second example, there's no reason to read the file as characters, since it will be sent on the wire as bytes anyway. Using byte streams all the way also avoids the encoding issue (apart from the information in the content-type header).

Answer 3

never read a file as chars unless you are reading a text file. xml is not text, it is a binary format. copy the file using normal InputStreams and byte[]s.

also, as @beny23 suggested in his comment, make sure you always copy streams using a loop, not a single read() (even if your buffer is big enough, it is not guaranteed that the InputStream will give you all the bytes in one call, even for a FileInputStream).