Infrastructure Software

The redirect looks ok to me. However, what does AGSenderServlet (specifically line 43) look like? If you are sending yourself a redirect, then you should handle it. :^)

- Saish

The AGSenderServlet is sending a file to the AGReceiverServlet using multipart and Postmethod object. Here is the code.

public class AGSenderServlet extends HttpServlet {
	public void doGet(HttpServletRequest request,
            HttpServletResponse response)
	throws ServletException, IOException {
		String filename = request.getParameter("filename");
		String ext = request.getParameter("ext");
		String serverName = request.getParameter("serverName");
		String port = request.getParameter("port");
		String path = null;
		String uri = "http://"+serverName+":"+port+"/AGReceiverServlet";
		
		File file = new File((this.getServletContext().getRealPath("/sync/out"))+"\\"+filename+'.'+ext);
		System.out.println("Test = "+file.getAbsolutePath());
		PostMethod post = new PostMethod(uri);
        Part[] parts = new Part[] {
            new FilePart(file.getName(), file) // File you want to upload
        };
        post.setRequestEntity(new MultipartRequestEntity(parts, post.getParams()));
 
        // Now perform the POST and check for errors
        HttpClient http = new HttpClient();
        int status = http.executeMethod(post);
        if (status != HttpStatus.SC_OK) {
            throw new IOException("Received HTTP status code " + status);
        }		
	}
	
	public void doPost(HttpServletRequest request,
            HttpServletResponse response)
	throws ServletException, IOException {
			doGet(request, response);
	}
}

Line 43 is just

throw new IOException("Received HTTP status code " + status);

What do you mean by " then you should handle it." ? I think I handle it. It redirects to the JSP filereceived.jsp which is hosted and available on the server (tried to access it directly by entering the url and it works).

Edited by: Foobrother on Sep 13, 2010 7:38 AM

I'm just thinking. Is it possible that at the end (just after doing the redirect) of the second servlet (AGReceiverServlet) it returns a response to the 1st one which is not HttpStatus.SC_OK (but still not an error status) and this throws an exception and stops the whole process before beeing able to run the content of the JSP (as I'm doing the test on the same server)?!

You are sending a HttpRequest to your own Servlet. That Servlet is responding with 302. Your sending Servlet is looking for 200, finding 302, and throwing your own exception. This error is 100% of your own making. See?

- Saish

I see indeed. I assumed "HttpStatus.SC_OK" represented all "non-error" status.

So in fact when it throws the exception it stops the process (the JSP is not processed). Because at the moment it doesn't run the code in the JSP.
I'll remove this status test to see what happens.

After removing the status test it doesn't throw any error now but it still doesn't run the JSP file.
I have also tried to change the redirect with response.sendRedirect("http://www.google.com"); but it didn't change anything.
However I do a println just after the response.sendRedirect() and it's printed.

I suggest you read the documentation on redirects for HttpClient found here. The API handles redirects within the same domain, but requires additional steps if the domain changes.

- Saish

Indeed, I didn't know it didn't handle different domains. It explains maybe why it doesn't work with Google. But it should work with my JSP which is hosted on exactly the same server?!

I've looked at your link. But I don't understand. It's speaking about the redirect in HttpClient. But I'm using the redirect of HttpServletResponse and I have found few code examples using sendRedirect with other domains (Google, etc...).

Take it apart step by step. You yourself wrote code that checks for HTTP status 200. You yourself wrote code that is redirecting and resulting in a status 302. You are throwing the IOException you posted earlier in the thread.

The docs for HttpClient indicate that if it receives a 302 response (remember, at this point it is the sender and not the responder that is at issue), it will seamlessly handle the redirect if in the same domain. If not in the same domain, you have to write additional code as demonstrated in the link I sent you.

After removing the check for status code 200, what happens?

- Saish

Ok so if I have well understood the response.sendRedirect() from the receiver is just sending a redirect request to the sender?!
So if a client calls Sender on ServerA, it will call Receiver on ServerB. Then Sender gets the redirect response from Receiver and calls the JSP file on ServerB. Am I right?!

But if it works like that, I don't understand how you get the location/URL to redirect from Sender servlet to JSP file.
Basically:

- Sender (ServerA) ==> Receiver (ServerB) done via PostMethod object (post) and HttpClient object (http) and this line "int status = http.executeMethod(post);"
- Receiver (ServerB ==> Sender (ServerA) done via response.sendRedirect(redirectURL); which makes a request on the Sender servlet to redirect to redirectURL ?!
- Sender (ServerA) ==> JSP file (ServerB) done via ???

If I apply the code of your link, it will get the location from the PostMethod object which is a URL to Receiver?!
And then to redirect to the location found in the header I need to do a reponse.sendRedirect() ?!

I'm totally confused.

Anyway, after removing the check for status code 200 nothing happens. No error, no exception but also not redirection to my JSP file (not code from the page run)

Here is my current code:
- AGSenderServlet » [http://pastebin.com/vW0YxGcE]
- AGReceiverServlet » [http://pastebin.com/nV39JKS1]

I have just tried to change my reponse.sendRedirect() with a dispatcher.forward(), but it didn't change the result :(

String redirectURL = "http://"+request.getServerName()+':'+request.getServerPort()+"/upTool/filereceived.jsp?filename="+fileName;
//response.sendRedirect(redirectURL);
RequestDispatcher dispatcher = request.getRequestDispatcher(redirectURL);
dispatcher.forward(request, response);

Ok. Let's make it simpler: client and server. Your client is initiating a HTTP post request. The server is responding with a HTTP 302 (found, redirect), that is returned the the client. The client should then issue another HTTP post request to the new redirected URL. The server then receives the second request which is handled, presumably by a JSP.

You should be able to see this exact behavior in a browser. What happens when you do so? Meaning, rather than using your client, use a browser. Does the redirect occur properly?

- Saish

Actually I never used my client to test it but only my browser. I use this URL to start testing: [http://localhost:8080/AGSenderServlet?filename=defacto&ext=zip&serverName=localhost&port=8080]
(parameter serverName should be different I was using 2 different servers)

When I load that servlet, my printouts from the 1st and 2nd servlet are displayed in my Tomcat (not the ones of the JSP) console but nothing changes on the browser. No redirection to another servlet or the JSP page. I just have a blank page.

Edited by: Foobrother on Sep 14, 2010 5:54 AM

AGSenderServlet has no code to send a response back to the browser.

- Saish

What do you mean by "send a response back to the browser"?

An HTML reponse? Like

PrintWriter out = response.getWriter();
response.println("Result");

Correct, with a call to close() in a finally block. (Or a JSP).

- Saish

Actually I managed to make the request.getRequestDispatcher() work.
In fact I just needed to put an absolut path from the webapps root instead of an absolute path from my drive root.
No it works fine.


Cheers.

Glad things are working. Best of luck.

- Saish

A relative path from the webapp's root.