Develop Reference

cannot use both TOMCAT server and my internet connection

I cannot have my tomcat server started and at the same time use internet.
either I can start Tomcat (in Eclipse) and internet is not available.
or I can access the internet but tomcat cannot be started.
Here the original probleme I had when I first wanted to use Tomcat and display my html page on localhost.
GRAVE: StandardServer.await: create[localhost:8005]: I find a way to start the Tomcat Server: in the terminal:
sudo lsof -i : 8005 # checks port 80
sudo route -n flush
sudo route add default 192.168.1.1
then I can use tomcat and localhost:8080 but my internet connexion is dead
if I want my internet connexion then I stop the tomcat server by clicking on the red square in eclipse and then in the terminal I do:
sudo route -n flush
sudo route add default 192.168.0.1
THen I can use internet but tomcat cannot be restarted. I have to undergo the first process.
this of course is a very boring process and I would like to know what 's wrong and how I could fix it.
I use tomcat 9 / Mac OS sierra / Eclipse Neon3

When you say "my internet connexion is dead", do you mean that your network connection drops or that your DNS lookups fail? (What do you think this command is doing and why are you performing it: sudo route add default 192.168.1.1?)
If your program is modifying your system's connectivity settings, I would strongly recommend against preventing it from doing that. There's no reason for it to do so at that level, a more appropriate place to set settings would be at some deploy stage.
Alternatively, you could run your app in a Docker container which I strongly suspect will solve your problem. Visit www.docker.com to learn more.

Connect JVisualVM to a Remote Wildfly Instance?

I'm trying to connect JVisualVM, running on my local machine, to a remote machine which is running a WildFly server (version 8.1.0, to be specific.)
I didn't configure the WildFly server myself, and I don't know who did, but I do know that I can log in as an administrative user from my local machine by pointing my browser at:
https://[ip address of the remote machine]:9443/console
Note that it's https, not ordinary http, and that the port for that has been set to 9443 (I think the default is 8080 or 9990 or something... IDK, I saw a lot of port numbers online. I have been explicitly told that http was disabled for this WildFly server).
I can SSH into the remote machine. I can navigate to the bin directory for WildFly and run jboss-client.sh. I have to connect on port 9999 (I think the default is 9990 for that?)
I copied the jboss-client.jar (under bin/client) to my local machine and ran JVisualVM from the command line like this:
.\jvisualvm.exe -cp:a C:\[path to]\jboss-client.jar
It launches fine. File > Add Remote Host: Then I entered the IP. OK. I right clicked on it under Remote in the tree and picked Add JMX Connection. I entered
service:jmx:http-remoting-jmx://[ip]:9999
I checked off that I wanted to use the security credentials and entered the username and password. Checked off to save the security credentials. Left "Do not require SSL Connection" unchecked. Hit OK. It immediately spat out the message
Cannot connect to admin#service:jmx:http-remoting-jmx://[ip]:9999 using service:jmx:http-remoting-jmx://[ip]:9999
I also tried the port 9443, 9990, and 8080 instead. None of those worked. I tried https instead of http in the protocol name. That also didn't work.
What am I missing? How is it that I can access the console, and connect with jboss-client.sh, but I can't use JVisualVM? Is there some log I can use somewhere to see what's wrong? Maybe someone can point out a configuration I've missed somewhere?
Not sure if it's important or not, but my local machine is running Windows 10 with JDK8 installed. The WildFly server is using Java 6 on CentOS 6.3.

You need to add the jboss-client.jar (or jboss-cli-client.jar) to the class path for JVisualVM. The library can be found in the bin/client directory of the WildFly install.
I used the following command to add the library to the class path.
jvisualvm --cp:a ~/servers/wildfly-10.0.0.Final/bin/client/jboss-client.jar
Then I used service:jmx:remote+http://[ip]:[port] and was able to connect.

I don't know if someone else is also (still) having the same issue (Wildfly10 on a remote machine where management console is available at 9443 with HTTPS). The following worked for me.
For ssh connections:
Starting jvisualvm with jboss-client.jar
jvisualvm --cp:a #JBOSS_HOME/bin/client/jboss-client.jar
Using the following connection string:
service:jmx:remote+https://remote-server:9443
NOTE: I used here remote+https
Provide username and password
Hope this helps.

you missed run jstatd command in remote host ,
this little program is RMI server that possible connection from client to remote host though you using jmx connection it used jmxrmi protocol for that connection .
so first in remote host create file name as security.policy with this contain :
grant codebase "file:${java.home}/../lib/tools.jar" {
permission java.security.AllPermission;
};
off course you must in file section for linux put explicit path and then of creation this file put it in bin directory of jdk.home
then you should run this command on remote host
$JAVA_HOME/bin/jstatd -J-Djava.security.policy=path of /security.policy -J-Djava.rmi.server.hostname=remote ip address -J-Djava.net.preferIPv4Stack=true
then you could connect to server off course with correct settings.

Include jboss-cli-client.jar and jboss-client.jar under \lib\visualvm\platform\lib and restart jvisualvm to pickup new jars.

Handshake failed - connection prematurally closed error when debugging Solr in Intellij

So i was going to debug my Solr filter plugins on Intellij Community Edition. After i ran the program from comand prompt with this command
java -jar start.jar -agentlib:jdwp=transport=dt_socket,server=y,suspend=y,address=8983
I started my Intellij debugger with this config:
Transport : socket
Debugger mode : attach
Host : localhost
Port : 8983
But when I ran the debugger I got this error:
Error running Debugger: Unable to open debugger port (localhost:8983):
java.io.IOException "handshake failed - connection prematurally closed"
Any idea how to fix this?

I got that error when trying to access to debug port on a Docker container.
If you are trying to access the debug port inside a Docker container make sure you are specifying the port as *:5005
E.g.
-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=*:5005
This has been changes since Java 9.
See: REGRESSION: Remote debugging does not work on JDK 9
It's not a bug. It's a security.
Before the JDK-8041435
If you have a server with EXT and INT interfaces and start Java process with address=5900 it binds to both interfaces and allow anybody from entire world to connect to your java process unless you block it on firewall.
After JDK-8041435 socket transport try to guess localhost and bind to localhost only. I.e. socket transport by default works only if both client and server are located on the same machine. It's not an easy task to guess proper localhost. so ever same-machine configuration might not work in some situation because of network setup.
You can restore old, insecure behavior using * (asteric)
i.e.
-agentlib:jdwp=transport=dt_socket,server=y,suspend=y,address=*:5900
should work exactly as it was before JDK-8041435
But it's recommended to explicitly specify ip address to bind when it possible.
And JDWP socket connector accept only local connections by default
The JDWP socket connector has been changed to bind to localhost only if no ip address or hostname is specified on the agent command line. A hostname of asterisk (*) may be used to achieve the old behavior which is to bind the JDWP socket connector to all available interfaces; this is not secure and not recommended.

It should be something like this,
java "-agentlib:jdwp=transport=dt_socket,server=y,suspend=y,address=8983" -jar start.jar
it's working now

I had this error with OpenJDK 11 inside Docker container and setting environment variable JAVA_DEBUG_PORT to "*:5005" worked for me.

You forgot to specify -Xdebug on the java command line.
Edit: As in
java -jar start.jar -Xdebug -agentlib:jdwp=transport=dt_socket,server=y,suspend=y,address=8983

It has helped me, at least in Intellij IDEA:
java -agentlib:jdwp=transport=dt_socket,server=y,suspend=y,address=0.0.0.0:5005
try to add ip 0.0.0.0.

Weblogic 10.3 can not be accessed after enableing Administrator port

I was was following this blog to set up some SSL connection. One-Way SSL with JAX-WS using JDeveloper 11gR1 and WLS 10.3.1
One of the steps mentioned is to enable the Administration port from weblogic console. I did that and change the Admin port. But, after saving everything get missed up the conclose closed and the I could not run the application form Jdeveloper .
The Error message is:
User 'principals=[weblogic, Administrators]' has administration role. All tasks by adminstrators must go through an Administration Port.
**** Authentication error while connecting to application server IntegratedWebLogicServer. Please check settings.
**** Failed to complete start-up of application server IntegratedWebLogicServer.
[Server Instance IntegratedWebLogicServer is shutting down. All applications currently running will be terminated and undeployed.]
[Forcing termination of IntegratedWebLogicServer]
taskkill /F /PID 7480
Process exited.
This blog: SOA OIM integration and WebLogic administration port
discuss this issue BUT under the assumption that I can access the weblogic console. But it is not happening for me.
I am using Jdeveloper 11.1.1.7 and the weblogic 10.3

The problem solved by deleting the system files for jdeveloper. This action will re insinuate the weblogic server. This file is located in my case in the following path: C:\Users\[UserName goes here]\AppData\Roaming\JDeveloper.
Check this thread form Oracle community for more information : Authentication error while connecting to application server IntegratedWebL

java remote debugging Tomcat app: Why does the JVM not listen?

I want to remote debug an application running in Tomcat 7. Tomcat is running as a service on a Win2008 server.
I added the following to the Java options in the Java Configuration Panel of Tomcat:
-Xdebug -Xrunjdwp:transport=dt_socket,address=4711,server=y,suspend=n and opened the firewall on my workstation and the server for this port.
But when I try debugging from IntelliJ 9 on my workstation, I get an error message Unable to open debugger port : java.net.ConnectException "Connection timed out: connect". The jvm is the standatd Sun/Oracle 64 bit JVM version 1.6.0_27.
I verified that the command line parameters are in use by accessing ManagementFactory.getRuntimeMXBean().getInputArguments() within the application deployed to Tomcat and logging the result to the log file.
I verified via Wireshark on my workstation and on the server that the TCP request on port 4711 is sent from my pc and arriving on the server, but there is is no answer. Running netstat -a on the server does not show a process listening on this port. So I assume somehow Tomcat/JVM does not start the remote debugging.

You need to put -Xdebug and -Xrunjdwp... on separate lines in the Java panel of the Tomcat Service Configuration Panel.
So having:
-Xdebug -Xrunjdwp:transport=dt_socket,address=4711,server=y,suspend=n
will not work, but:
-Xdebug
-Xrunjdwp:transport=dt_socket,address=4711,server=y,suspend=n
will.