Java

FTP Socket Buffer and Address Options

Demonstrates the SoRcvBuf, SoSndBuf, PreferIpv6, and ClientIpAddress properties.

Background: These are low-level knobs for specific situations. Larger send/receive buffers can improve throughput on high-bandwidth, high-latency links, though the defaults suit the common case. PreferIpv6 only matters when a hostname resolves to both address families, choosing which to try first. ClientIpAddress is normally left unset; set it on a multihomed host to bind the outgoing connection to a particular local interface. Change any of these only with a concrete reason.

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Java

import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[])
  {
    boolean success = false;

    CkFtp2 ftp = new CkFtp2();

    ftp.put_Hostname("ftp.example.com");
    ftp.put_Username("myFtpLogin");

    //  SoRcvBuf and SoSndBuf set the TCP socket receive/send buffer sizes.  The defaults are tuned for
    //  the common case; larger values can sometimes help throughput on high-latency links.
    ftp.put_SoRcvBuf(4194304);
    ftp.put_SoSndBuf(524288);

    //  PreferIpv6 (default false) chooses IPv6 over IPv4 when a hostname resolves to both.
    ftp.put_PreferIpv6(false);

    //  ClientIpAddress is normally left unset; set it on a multihomed host to bind the outgoing
    //  connection to a specific local interface.
    ftp.put_ClientIpAddress("192.168.1.50");

    //  Normally you would not hard-code the password in source.  You should instead obtain it
    //  from an interactive prompt, environment variable, or a secrets vault.
    ftp.put_Password("myPassword");

    success = ftp.Connect();
    if (success == false) {
        System.out.println(ftp.lastErrorText());
        return;
        }

    System.out.println("Connected with custom socket options.");

    success = ftp.Disconnect();
    if (success == false) {
        System.out.println(ftp.lastErrorText());
        return;
        }
  }
}