Troubleshooting: Asmack stream error (host-unknown)

Problem

When trying to write an Android demo with asmack, an error named 'host-unknown' appears. Here is the error seen in LogCat:

03-16 08:31:10.671: I/getConnection(795): connect success
03-16 08:31:10.905: W/System.err(795): stream:error (host-unknown)
03-16 08:31:10.905: W/System.err(795):    at org.jivesoftware.smack.PacketReader.parsePackets(PacketReader.java:261)
03-16 08:31:10.912: W/System.err(795):    at org.jivesoftware.smack.PacketReader.access$000(PacketReader.java:44)
03-16 08:31:10.912: W/System.err(795):    at org.jivesoftware.smack.PacketReader$1.run(PacketReader.java:71)

Below is the code used:

private static String host = "172.16.131.99";
private static int port = 5222;

private Button btnLogin;

private static XMPPConnection connection = null;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    btnLogin = (Button) findViewById(R.id.btnLogin);
    btnLogin.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            if (login()) {
                showMessage("Login success");
            } else {
                showMessage("Login failure");
            }
        }

    });
}

private XMPPConnection getConnection() {
    if (connection == null) {
        ConnectionConfiguration config = new ConnectionConfiguration(host, port, "");
        // use TLS
        config.setSecurityMode(SecurityMode.required);
        try {
            connection.connect();
            Log.i("getConnection", "connect success");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    return connection;
}

private boolean login() {
    try {
        // login
        getConnection().login("admin", "123456");
        Log.i("Login", "login success");

        // set status
        Presence presence = new Presence(Presence.Type.available);
        getConnection().sendPacket(presence);
        Log.i("Login", "set status success");

        return true;
    } catch (Exception e) {
        e.printStackTrace();
    }

    return false;
}

private void showMessage(String message) {
    Toast.makeText(this, message, 1000).show();
}

Solution

The 'host-unknown' error may be caused by an incomplete initialization of the connection. After checking if connection == null, make sure to initialize it properly with connection = new XMPPConnection(config);.

Additionally, the issue may stem from not specifying the service name in the constructor of ConnectionConfiguration. The service name should match the XMPP domain. For instance, if the user's email is user@something.com, the service name should be "something.com".

You can determine the correct service name by logging the service name after connection.connect() succeeds:

Log.e("Service Name", xmpp.getServiceName());

Then, use the service name in the constructor:

ConnectionConfiguration config = new ConnectionConfiguration(host, port, "something.com");
connection = new XMPPConnection(config);

Conclusion

This approach should address the 'host-unknown' error. For further reference, see the original discussion on Stack Overflow.