Develop Reference

How to specify the network interface when using Naming Service lookup using Oracle Java ORB

So I'm currently hosting a service which utilizes Oracle's Interoperable Naming Service (INS) according to tutorial listed below. This service deploys a servant on one machine and registers it with the INS, we'll call this machine A.
Properties properties = System.getProperties( );
properties.put( "com.sun.CORBA.POA.ORBPersistentServerPort",
Integer.toString(1060);
ORB orb = ORB.init( args, properties );
ServiceImpl servant = new ServiceImpl( );
POA rootPOA = POAHelper.narrow( orb.resolve_initial_references( "RootPOA" ));
rootPOA.the_POAManager().activate();
rootPOA.activate_object( servant );
((com.sun.corba.se.impl.orb.ORBImpl) orb).
register_initial_reference("PingService",
rootPOA.servant_to_reference(servant));
System.out.println( "INS Server is Ready...");
orb.run();
https://docs.oracle.com/javase/8/docs/technotes/guides/idl/INStutorial.html
When I use a client on the same machine according to the tutorial, everything works just fine. However, when I attempt to do a lookup over LAN, when the INS Server is hosted on Machine A and the client is on Machine B I get an error when narrowing the reference.
String[] argv = new String[]{"-ORBInitRef",
"PingService=corbaloc:iiop:1.2#"
+ ORBIP + ":" + ORBPort + "/PingService"};
ORB orb = ORB.init( argv, null );
org.omg.CORBA.Object object = orb.resolve_initial_references(
"PingService" );
Service fileRef = ServiceHelper.narrow( object ); // <----- error
I set the server as 192.168.0.XXX and it is accessible by machine B, and get error somewhere along these lines. AFAIK the connection is being made to the naming service and the object located in the service, but when it tries to look up the object it uses an incorrect interface on machine A. Then the error is returned to machine B.
com.sun.corba.se.impl.transport.SocketOrChannelConnectionImpl <init>
WARNING "IOP00410201: (COMM_FAILURE)Connection failure: socketType: IIOP_CLEAR_TEXT; hostname: 127.0.1.1; port:1060"
org.omg.CORBA.COMM_FAILURE: vmcid: SUN minor code: 201 completed: No
connectFailure
So my question is, is there a way to specify exactly which interface the naming service can use when it does the lookup? I tried on both a Windows host and a Linux host. The linux host used an iface which wasn't listed but was in the /etc/hosts file and the Windows host used an IP of the last interface listed in ipconfig (a 172.xx.. IP). Tested both on vbox with bridge enabled. Is there an effective way to specify the network interface? My requirement is for the server and client to exist independently on the same LAN. Setting the ORBInitialHost property on the server didn't do anything.

the problem here is that the client machine is searching for the server locally this why it's writing Connection failure: socketType: IIOP_CLEAR_TEXT; hostname: 127.0.1.1; port:1060
So in the client code instead of initializing the properties like this :
String[] argv = new String[]{"-ORBInitRef", "PingService=corbaloc:iiop:1.2#"
+ ORBIP + ":" + ORBPort + "/PingService"};
ORB orb = ORB.init( argv, null );
try initializing it like this :
Properties props = new Properties();
props.put("org.omg.CORBA.ORBInitialHost",ORBIP);
props.put("org.omg.CORBA.ORBInitialPort","1060");
ORB orb = ORB.init(args,props);
in the ORBIP variable put the server IP address in the LAN .
you tried the ORBInitialHost property on the server but it doesn't do anything because he's running locally . this property must be used in the client side to know the exact hosting point of the server.

How to setup proxy host and port to IBM MQConnectionFactory

I need to specify a custom proxy host and port for an MQConnectionFactoy and I saw that the set proxy host and port are not supported anymore. I am using exactly this 8.0 version and I don't want to downgrade.
https://www.ibm.com/support/knowledgecenter/en/SSFKSJ_8.0.0/com.ibm.mq.javadoc.doc/WMQJMSClasses/com/ibm/mq/jms/MQConnectionFactory.html#setProxyHostName(java.lang.String)
Does anyone know how I can achieve this? Is there a JmsConnectionFactoryProxy which can wrap the MQConnectionFactory?
Thanks in advance.
Regards,
C

I've been able to achieve what I wanted with ProxySelector.
I've added a custom rule for the case when scheme is "socket", hostname = "MQ_HOSTNAME" and port = "MQ_PORT" to return a custom created proxy.
SocketAddress socketAddress = new InetSocketAddress(proxyHost, proxyPort);
Proxy proxy = new Proxy(Type.SOCKS, socketAddress);

Hiveserver2 not responding

I have a hiveserver(hiveserver2) running on port 10000.
If I run command:
netstat -nl | grep 10000
I get:
tcp 0 0 0.0.0.0:10000 0.0.0.0:* LISTEN
so the server is up and running.
My hive-site.xml settings:
<property>
<name>hive.server2.thrift.port</name>
<value>10000</value>
</property>
My code:
public class ThriftAgent {
private static final String HOST = "localhost";
private static final int PORT = 10000;
public static void main(String[] args) throws Exception {
TSocket transport = new TSocket(HOST, PORT);
transport.open();
TBinaryProtocol protocol = new TBinaryProtocol(transport);
Client client = new ThriftHive.Client(protocol);
client.execute("show tables");
final List<String> results = client.fetchAll();
for (String result : results) {
System.out.println(result);
}
transport.close();
}
}
I have tried different URL combos but it freezes at client.execute() and does not go any further than that. It does not throw any exceptions either.
I have also tried to disable authentication but that did not help either as per thread
Requests hang when using Hiveserver2 Thrift Java client
If I connect through JDBC to same host it works.
Also if I start HiveServer (not hiveserver2) it works so something is fishy with hiveserver2.

Well, with no error output to guide us, it could be several things.
It's been a while since I set up a Hive2 Server, but, you may want to define the IP address(or host) in the hive-site.xml using the hive.server2.thrift.bind.host property.
If you set the property above to 'localhost' you'll need to make certain the /etc/hosts file is set to resolve you properly, and if it's on another machine and you use the name, same thing. I would recommend testing with an IP address, and then move to name.
The comment requesting more information is a good one though, there is not much to go on here. What version of Hive2 are you using? What Hadoop distro? There will be differences affecting your solution depending on the answers.

Check if you have IPv6 disabled or in your environment settings make sure you add this to your java options:
-Djava.net.preferIPv4Stack=true
For the first one you should set this parameters on your /etc/sysctl.conf file:
#disable ipv6
net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
net.ipv6.conf.lo.disable_ipv6 = 1
After a reboot check if it's disabled with:
cat /proc/sys/net/ipv6/conf/all/disable_ipv6
For the second one you can add this in you hadoop-env.sh
export HADOOP_OPTS="$HADOOP_OPTS -Djava.net.preferIPv4Stack=true
or in your .bashrc file:
alias java="java -Djava.net.preferIPv4Stack=true"

Connect remotely to an H2 Database using a Java Application

I'm having the following problem:
When I try to createTcpServer with my external IP address (the PC's IP and not my local IP = the one we see as an output after running ipconfig in cmd.exe) the following error occurs:
Error with Server: Exception opening port "9092" (port may be in use), cause: "java.net.BindException: Cannot assign requested address: JVM_Bind" [90061-169]
However, the port is not in use. I've checked that using netstat -a -n .
I have enabled my external IP and I have disabled the firewall from the router. My external IP can now be pinged.
Please help me.
Update: Here is my code to start the tcp server.
package businessApp;
import org.h2.tools.Server; //imports the server utility
public class startTcpServerForH2 {
Server server; //the server's instance variable
private static final String SERVER_IP = "192.168.1.101"; //fixed IP of the server
private static final String SERVER_PORT = "9092"; //fixed port the server is listening to
public void tcpServer() { //method responsible to create the tcp server
optionPane optPane = new optionPane(); //option pane for debugging purposes, shows the server's status
try { //catches any server related errors, if the connection is broken etc.
//server uses the IP and port defined earlier, allows other computers in the LAN to connect and implements the secure socket layer (SSL) feature
server = Server.createTcpServer( //create tcp server
new String[] { "-tcpPort" , SERVER_PORT , "-tcpAllowOthers" , "-tcpSSL" }).start();
System.out.println(server.getStatus()); //prints out the server's status
optPane.checkServerStatus(server.getStatus()); //prints out the server's status on the option pane as well
} catch(Exception ex){
System.out.println("Error with Server: " + ex.getMessage());
}
}
public static void main(String[] args){
startTcpServerForH2 tcpServ = new startTcpServerForH2(); //create a new server object
tcpServ.tcpServer(); //starts the tcp server
}
}
Second Update: here is the h2Connection code.
package businessApp;
import java.sql.*; //imports sql features
//Class responsible for connection with H2 Database Engine
public class h2Connection {
Connection conn; //connection variable
DatabaseMetaData dbmd; /** Metadata variable which include methods such as the following:
* 1) Database Product Name
* 2) Database Product Version
* 3) URL where the database files are located (in TCP mode)
*/
Statement stm; //statements variable
ResultSet rst; //result sets variable
private static final String SERVER_IP = "..."; //here I enter my WAN_IP
private static final String SERVER_PORT = "9092";
public Connection connectionToH2(Connection connt) {
optionPane optPane = new optionPane(); //create new option pane object
String outputConn = null; //declare & initialize string which will hold important messages
try {
Class.forName("org.h2.Driver"); //Driver's name
/** The String URL is pertained of the following:
* 1) jdbc which java implements so that it can take advantage of the SQL features
* 2) Which Database Engine will be used
* 3) URL where the files will be stored (as this is a TCP connection)
* 4) Schema: businessApp
* 5) Auto server is true means that other computers can connect with the same databse at any time
* 6) Port number of the server is also defined
*/
String url = "jdbc:h2:tcp://" + SERVER_IP + ":" + SERVER_PORT + "/C:/Databases/businessApp;IFEXISTS=TRUE";
System.out.println(url); //prints out the url the database files are located as well as the h2 features used (SSL)
connt = DriverManager.getConnection(url, "sa", ""); //Driver Manager defines the username & password of the database
System.out.println(connt.getCatalog()); //prints out the database schema
optPane.checkServerStatus(connt.getCatalog()); //prints out the database schema on the option pane as well
connt.setAutoCommit(false); //set AutoCommit to false to control commit actions manually
//outputs H2 version and the URL of the database files which H2 is reading from, for confirmation
dbmd = connt.getMetaData(); //get MetaData to confirm connection
outputConn = "Connection to "+dbmd.getDatabaseProductName()+" "+
dbmd.getDatabaseProductVersion()+ " with the URL " + dbmd.getURL()+" was successful.\n";
System.out.println(outputConn); //outputs the message on the system (NetBeans compiler)
optPane.checkH2Connection(outputConn); //outputs the message on top of the frame
} catch (ClassNotFoundException ex){ //In case there is an error for creating the class for the Driver to be used
System.out.println("Error creating class: " + ex.getMessage());
} catch(SQLException ex){ //Any error associated with the Database Engine
System.out.println("SQL error: " + ex.getMessage());
optPane.checkServerStatus("SQL error: " + ex.getMessage());
}
return connt; //As the method is not void, a connection variable must be returned
}
}
When I want to connect to the h2 database, I make a new h2Connection object and use it to connect. I have followed the H2 manual word by word. What more do you need?

As suggested in the command line help shown below, Protection against Remote Access advises the following:
By default this database does not allow connections from other machines when starting the H2 Console, the TCP server, or the PG server. Remote access can be enabled using the command line options -webAllowOthers, -tcpAllowOthers, -pgAllowOthers.
See the documentation for important caveats regarding these options.
Addendum: Works for me, as long as I restart the Server after opening the firewall; you don't need the setProperty() line at all; the LAN IP to which your WAN_IP forwards port 9092 should be your host IP address; then you can open a shell via your WAN_IP:
java -cp h2.jar org.h2.tools.Shell -url
jdbc:h2:tcp://WAN_IP/~/path/to/test;ifexists=true"
Command line help:
$ java -cp .:/opt/h2/bin/h2.jar org.h2.tools.Shell -?
Interactive command line tool to access a database using JDBC.
Usage: java org.h2.tools.Shell
Options are case sensitive. Supported options are:
[-help] or [-?] Print the list of options
[-url ""] The database URL (jdbc:h2:...)
[-user ] The user name
[-password ] The password
[-driver ] The JDBC driver class to use (not required in most cases)
[-sql ""] Execute the SQL statements and exit
[-properties ""] Load the server properties from this directory
If special characters don't work as expected, you may need to use
-Dfile.encoding=UTF-8 (Mac OS X) or CP850 (Windows).
See also http://h2database.com/javadoc/org/h2/tools/Shell.html
$ java -cp /opt/h2/bin/h2.jar org.h2.tools.Server -?
Starts the H2 Console (web-) server, TCP, and PG server.
Usage: java org.h2.tools.Server
When running without options, -tcp, -web, -browser and -pg are started.
Options are case sensitive. Supported options are:
[-help] or [-?] Print the list of options
[-web] Start the web server with the H2 Console
[-webAllowOthers] Allow other computers to connect - see below
[-webDaemon] Use a daemon thread
[-webPort ] The port (default: 8082)
[-webSSL] Use encrypted (HTTPS) connections
[-browser] Start a browser connecting to the web server
[-tcp] Start the TCP server
[-tcpAllowOthers] Allow other computers to connect - see below
[-tcpDaemon] Use a daemon thread
[-tcpPort ] The port (default: 9092)
[-tcpSSL] Use encrypted (SSL) connections
[-tcpPassword ] The password for shutting down a TCP server
[-tcpShutdown ""] Stop the TCP server; example: tcp://localhost
[-tcpShutdownForce] Do not wait until all connections are closed
[-pg] Start the PG server
[-pgAllowOthers] Allow other computers to connect - see below
[-pgDaemon] Use a daemon thread
[-pgPort ] The port (default: 5435)
[-properties ""] Server properties (default: ~, disable: null)
[-baseDir ] The base directory for H2 databases (all servers)
[-ifExists] Only existing databases may be opened (all servers)
[-trace] Print additional trace information (all servers)
The options -xAllowOthers are potentially risky.
For details, see Advanced Topics / Protection against Remote Access.
See also http://h2database.com/javadoc/org/h2/tools/Server.html

Java RMI connection to localhost at home network can't find correct remote module

I have been working on this project where two modules on different machines need to be in communication through RMI.
I start both client and server modules on my laptop. RMI seems to work correctly when i am at work and connected to work network, but when i am home, connected to my home network it does not work. It says remote object could not be found.
Here is the method i use at CLIENT side to get the reference to remote object
public static MyRMIApp getRemoteApp() throws RemoteException, NotBoundException, AccessException {
Registry registry = LocateRegistry.getRegistry("localhost", 28999); // tried 127.0.0.1 instead of localhost here, still not working
MyRMIApp app = (MyRMIApp) registry.lookup("COM");
return app;
}
Digging up a bit with some debugging, when i check the object value returned from getRemoteApp method, it shows me the end point is 67.215.65.132. Which is openDNS i am using to connect to internet. Shouldn't that be 127.0.0.1 ?
Then i used my mobile internet and tried again. It seems to be working but end-point is not 127.0.0.1 again it is the address assigned to me, which is 192.168.x.x
So can anybody please tell me what is wrong i am doing here ? I really would appreciate the help.
Oh and this is the piece of code at SERVER side
//Somwhere up top
private final static MyRMIApp rmiApp = new RMIServer();
//Down below
MyRMIApp stub = (MyRMIApp) UnicastRemoteObject.exportObject(rmiApp, 0);
Registry registry = LocateRegistry.createRegistry(28999);
registry.rebind("COM", stub);

See item A.1 of the RMI FAQ: specifically, 'The appropriate workaround is to set the system property java.rmi.server.hostname when starting the server.'