Daniel Hagen said:Christophe said:Sam,
Unfortunately, this is not DNS caching problem. When I ping (on the same
machine where my java application is running) the domain, the new ip address
is exact (after a few seconds, of course) but it is never exact in the java
application. The only way to use the new ip, is to restart the java
application.
So it is a DNS caching problem, but at the java level
Christophe
Just a thought (not considered very carefully, not tested and a very
ugly workaround):
Couldn't you use the API of your underlying OS via JNI to get the IP and
set the HTTP Host Header "manually" for the URLConnection?
Something like:
String formattedIp = someIpFormatMethod(
someNativeGetHostByNameMethod("a.domain") );
URL url = new URL("http://" + formattedIp);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestProperty( "Host", "a.domain");
[...]
Daniel
Christophe said:addressChristophe said:Sam,
Unfortunately, this is not DNS caching problem. When I ping (on the same
machine where my java application is running) the domain, the new ip
javais exact (after a few seconds, of course) but it is never exact in the
application. The only way to use the new ip, is to restart the java
application.
So it is a DNS caching problem, but at the java level
Christophe
Just a thought (not considered very carefully, not tested and a very
ugly workaround):
Couldn't you use the API of your underlying OS via JNI to get the IP and
set the HTTP Host Header "manually" for the URLConnection?
Something like:
String formattedIp = someIpFormatMethod(
someNativeGetHostByNameMethod("a.domain") );
URL url = new URL("http://" + formattedIp);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestProperty( "Host", "a.domain");
[...]
Daniel
Hi Daniel,
Your workaround works fine !
The connection.setRequestProperty("Host","...") command was the piece of
puzzle that was missing to me to solve the virtual hosting problem !
Thank you very much
Christophe
marcus said:I am impressed -- I had no idea you could set the host after the
connection. very cool
Christophe said:Christophe Darville wrote:
Sam,
Unfortunately, this is not DNS caching problem. When I ping (on the same
machine where my java application is running) the domain, the new ip
address
is exact (after a few seconds, of course) but it is never exact in the
java
application. The only way to use the new ip, is to restart the java
application.
So it is a DNS caching problem, but at the java level
Christophe
Just a thought (not considered very carefully, not tested and a very
ugly workaround):
Couldn't you use the API of your underlying OS via JNI to get the IP and
set the HTTP Host Header "manually" for the URLConnection?
Something like:
String formattedIp = someIpFormatMethod(
someNativeGetHostByNameMethod("a.domain") );
URL url = new URL("http://" + formattedIp);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestProperty( "Host", "a.domain");
[...]
Daniel
Hi Daniel,
Your workaround works fine !
The connection.setRequestProperty("Host","...") command was the piece of
puzzle that was missing to me to solve the virtual hosting problem !
Thank you very much
Christophe
Security.setProperty("networkaddress.cache.ttl", "0");
Security.setProperty("networkaddress.cache.negative.ttl", "0");import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.Authenticator;
import java.net.HttpURLConnection;
import java.net.Inet4Address;
import java.net.MalformedURLException;
import java.net.PasswordAuthentication;
import java.net.URL;
import java.net.UnknownHostException;
import java.security.Security;
import java.util.concurrent.TimeUnit;
import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpException;
import org.apache.commons.httpclient.UsernamePasswordCredentials;
import org.apache.commons.httpclient.auth.AuthScope;
import org.apache.commons.httpclient.methods.GetMethod;
public class DNSCachingTest {
public static final String host = "xyz.dyndns.org";
public static final int port = 8086;
public static final String auth[] = { "username", "password" };
public static void main(String[] args) {
// System.getProperties().list(System.out);
System.out.println("networkaddress.cache.ttl - "
+ Security.getProperty("networkaddress.cache.ttl"));
System.out.println("networkaddress.cache.negative.ttl - "
+ Security.getProperty("networkaddress.cache.negative.ttl"));
Security.setProperty("networkaddress.cache.ttl", "0");
Security.setProperty("networkaddress.cache.negative.ttl", "0");
boolean flag = true;
while (flag) {
printIp();
System.out.println("---------");
checkUrlConnection();
System.out.println("---------");
checkHttpClient();
System.out.println("---------");
try {
TimeUnit.SECONDS.sleep(60);
} catch (InterruptedException e) {
e.printStackTrace();
}
// flag = false;
}
}
public static void printIp() {
try {
System.out.println("Address: " + Inet4Address.getByName(host));
} catch (UnknownHostException e) {
e.printStackTrace();
}
}
public static void checkUrlConnection() {
URL url;
try {
url = new URL("http://" + host + ":" + port + "/");
if (auth != null) {
Authenticator.setDefault(new Authenticator() {
protected PasswordAuthentication getPasswordAuthentication() {
return new PasswordAuthentication(auth[0], auth[1]
.toCharArray());
}
});
}
HttpURLConnection con = (HttpURLConnection) url.openConnection();
con.setConnectTimeout(10000);
con.setReadTimeout(10000);
int responseCode = con.getResponseCode();
if (responseCode == HttpURLConnection.HTTP_OK) {
BufferedReader br = new BufferedReader(new InputStreamReader(
con.getInputStream()));
while (br.readLine() != null)
;
System.out.println("checkUrlConnection: ok");
} else {
System.out.println("Response code (checkUrlConnection): "
+ responseCode);
}
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
public static void checkHttpClient() {
try {
HttpClient httpClient = new HttpClient();
httpClient.getHttpConnectionManager().getParams()
.setConnectionTimeout(10000);
httpClient.getHttpConnectionManager().getParams()
.setConnectionTimeout(10000);
if (auth != null) {
httpClient.getState().setCredentials(new AuthScope(host, port),
new UsernamePasswordCredentials(auth[0], auth[1]));
}
GetMethod method = new GetMethod("http://" + host + ":" + port
+ "/");
int responseCode;
responseCode = httpClient.executeMethod(method);
if (responseCode == HttpURLConnection.HTTP_OK) {
BufferedReader br = new BufferedReader(new InputStreamReader(
method.getResponseBodyAsStream()));
while (br.readLine() != null)
;
System.out.println("checkHttpClient: ok");
} else {
System.out.println("Response code (checkHttpClient): "
+ responseCode);
}
} catch (HttpException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}nslookup xyz.dyndns.orgSecurity.setProperty("networkaddress.cache.ttl", "0");
Security.setProperty("networkaddress.cache.negative.ttl", "0");Want to reply to this thread or ask your own question?
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