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From: "Oscar Usifer" <oscaruser@programmer.net>
To: commons-user@jakarta.apache.org
Date: Mon, 23 Jul 2007 18:41:43 -0500
Subject: [commons-net] How to add timeouts to FTP client connections?
Message-Id: <20070723234143.192F71BF28D@ws1-1.us4.outblaze.com>

Folks,

I am writing an ftp client that uploads a file to more than one (many) ftp =
servers simultaneously. I want to add some fault tolerance so that if one s=
erver goes offline during the transfer, the upload is completed to the runn=
ing servers. I've tried to capture this situation by blocking packets (via =
iptables) on one ftp server, and seeing if it triggers a timeout condition/=
exception (from setting setSoTimeout) in the ftp client, but unfortuantley =
the connection only hangs. Note I am using rwinston's commons-net-ftp-2.0.0=
-SNAPSHOT.jar. The code below is a command line example of the ftp client. =
Any suggestions?

Thanks,
OSC

import java.io.OutputStream;
import org.apache.commons.net.ftp.FTPClient;
public class FTPServer {
=A0=A0 boolean online =3D true;
=A0=A0 FTPClient client =3D null;
=A0=A0 String hostname =3D null;
=A0=A0 OutputStream os =3D null;
}

import java.io.FileInputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.Random;

import org.apache.commons.net.PrintCommandListener;
import org.apache.commons.net.ftp.FTP;
import org.apache.commons.net.ftp.FTPClient;
import org.apache.commons.net.ftp.FTPConnectionClosedException;
import org.apache.commons.net.ftp.FTPReply;


public class Fdb {
   public static final String USAGE =3D
      "Usage: Fdb <local file>\n" +
      "\nUploads local file to remote ftp servers in binary transfer mode.\=
n";

   public static void main(String[] args) {
      String[]    ftphost =3D { "filedb1.test", "filedb2.test"};
      FTPServer[] ftpsvr =3D new FTPServer[ftphost.length];
      File fl =3D null;
      FileInputStream is =3D null;

      if (args.length =3D=3D 0) {
         System.out.println(USAGE);
         System.exit(-1);
      }

      try {
         fl =3D new File(args[0]);
         is =3D new FileInputStream(fl);
      } catch (Exception e) {
         System.exit(-1);
      }

      // data type initialization
      for (int i =3D 0; i < ftpsvr.length; ++i) {
         ftpsvr[i] =3D new FTPServer();
         ftpsvr[i].client =3D new FTPClient();
         ftpsvr[i].client.setConnectTimeout(1000); // one sec timeout
         try {
            ftpsvr[i].client.setSoTimeout(1000);
         } catch(Exception e) {}
         ftpsvr[i].client.addProtocolCommandListener(new PrintCommandListen=
er(
                  new PrintWriter(System.out)));
         ftpsvr[i].hostname =3D ftphost[i];
      }

      // ftp connections
      for (int i =3D 0; i < ftpsvr.length; i++) {
         try {
            ftpsvr[i].client.connect(ftpsvr[i].hostname);

            if (FTPReply.isPositiveCompletion(ftpsvr[i].client.getReplyCode=
())) {
               System.out.println(ftpsvr[i].hostname + " ftp connection");
               ftpsvr[i].online =3D true;
               System.out.println(ftpsvr[i].hostname + " marked server onli=
ne");
            } else {
               System.out.println(ftpsvr[i].hostname + " no ftp connection"=
);
               System.out.println(ftpsvr[i].hostname + " marked server offl=
ine");
            }
         } catch (Exception e) {
            ftpsvr[i].online =3D false;
         }
      }

      // connection negotiation
      for (int i =3D 0; i < ftpsvr.length; i++) {
         if (ftpsvr[i].online) {
            ftpsvr[i].client.enterLocalPassiveMode();
            try {
               ftpsvr[i].client.login("ftp", "");
               ftpsvr[i].client.setFileType(FTPClient.BINARY_FILE_TYPE);
               ftpsvr[i].client.changeWorkingDirectory("/pub/incoming");

               // added random number for testing purposes
               ftpsvr[i].os =3D ftpsvr[i].client.storeFileStream((new Rando=
m()).nextInt(1000) + args[0]);
            } catch (java.io.IOException e) {
               ftpsvr[i].online =3D false;
            }
         }
      }

      // Writing input byte streams to ftp server destinations
      byte buf[] =3D new byte[8192];

      int bytesRead =3D 0;

      try {
         bytesRead =3D is.read(buf);
      } catch(Exception e) {}

      System.out.println("writing data");
      while (bytesRead !=3D -1) {
         // write data out to ftp servers
         for (int i =3D 0; i < ftpsvr.length; i++) {
            try {
               if (ftpsvr[i].online) {
                  if (FTPReply.isPositivePreliminary(ftpsvr[i].client.getRe=
plyCode())
                        && ftpsvr[i].os !=3D null) {
                     System.out.print(".");
                     ftpsvr[i].os.write(buf, 0, bytesRead);
                  } else {
                     System.out.println("non - positive reply on " + ftpsvr=
[i].hostname);
                  }
               }
            } catch (Exception e1) {
               // here we're assuming any exception was generated by
               // an I/O fault related to writing to the ftp server,
               // thus the server is offline

               System.out.println("**FAULT writing to " + ftpsvr[i].hostnam=
e);
               ftpsvr[i].online =3D false;
            }
         }

         try {
            bytesRead =3D is.read(buf);
         } catch (Exception e) {}
      }

      System.out.println("done.");
      try {
         is.close();
      } catch (Exception e) {}

     for (int i =3D 0; i < ftpsvr.length; i++) {
        if (ftpsvr[i].online) {
           System.out.println("closing output stream " + ftpsvr[i].hostname=
);
           try {
              ftpsvr[i].os.close();
              ftpsvr[i].client.completePendingCommand();
              ftpsvr[i].client.logout();
              ftpsvr[i].client.disconnect();
           } catch (Exception e) {}
        }
     }
   }
}


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