RMI Registry

Hi!
Is it possible to install more then one RMI Registry service
in the same machine? If so, how can the clients make the
distinction between objects ?
Thanks!

Yes, just bind each "registry" to a different port. The default port is 1099. So, for example, you can bind a "registry" to port 1098 with the following command:
rmiregistry 1098Of-course, if port 1098 is already being used, the above command will fail -- and you will get an error message.
Hope this helps.
Good Luck,
Avi.

Similar Messages

Can anybody help me to understand this RMI registry service code?

RMI is so difficult to me. please let me know following code what it means.
If this class is instantiated with 50000 port number,
Does RMI Registry Service get started with 50000 port number in place of rmiregistry commands?
And I don't have to execute rmiregistry command?
thanks in advance.
import java.rmi.AccessException;
import java.rmi.AlreadyBoundException;
import java.rmi.NotBoundException;
import java.rmi.Remote;
import java.rmi.RemoteException;
import java.rmi.registry.Registry;
import java.rmi.server.ObjID;
import java.rmi.server.RemoteServer;
import java.util.Enumeration;
import java.util.Hashtable;
import sun.rmi.server.UnicastServerRef;
import sun.rmi.transport.LiveRef;
* Registry implementation.
* @version 1.0
public class RegistryImpl extends RemoteServer implements Registry {
     private static final long serialVersionUID = -7162736590129110751;
     private Hashtable bindings;
    private static ObjID id = new ObjID(0);
     * @param i port number
     * @throws RemoteException
    public RegistryImpl(int i) throws RemoteException {
        bindings = new Hashtable(101);
        LiveRef liveref = new LiveRef(id, i);
        setup(new UnicastServerRef(liveref));
    private void setup(UnicastServerRef unicastserverref) throws RemoteException {
        super.ref = unicastserverref;
        unicastserverref.exportObject(this, null, true);
     * Lookup a remote object.
     * @param name Name of the remote object.
     * @return Remote object of the specified name.
    public Remote lookup(String name) throws RemoteException, NotBoundException {
//        Logger.debug("NamingService", "lookup: " + name);
        Remote obj;
        synchronized(bindings) {
            obj = (Remote)bindings.get(name);
            if(obj == null)
                throw new NotBoundException(name);
        return obj;
     * Binds the specified name to a remote object.
     * @param name A URL-formatted name for the remote object.
     * @param obj A reference for the remote object (usually a stub).
    public void bind(String name, Remote obj) throws RemoteException, AlreadyBoundException, AccessException {
//        Logger.debug("NamingService", "bind: " + name);
        checkAccess("Registry.bind");
        synchronized(bindings) {
            if(bindings.containsKey(name))
                throw new AlreadyBoundException(name);
            bindings.put(name, obj);
     * Destroys the binding for the specified name that is associated with a remote object.
     * @param name A URL-formatted name for the remote object.
    public void unbind(String name) throws RemoteException, NotBoundException, AccessException {
//        Logger.debug("NamingService", "unbind: " + name);
        checkAccess("Registry.unbind");
        synchronized(bindings) {
            if(!bindings.containsKey(name))
                throw new NotBoundException(name);
            bindings.remove(name);
     * Rebinds the specified name to a new remote object. Any existing binding
     * for the name is replaced.
     * @param name A URL-formatted name for the remote object.
     * @param obj A reference for the remote object (usually a stub).
    public void rebind(String name, Remote obj) throws RemoteException, AccessException {
//        Logger.debug("NamingService", "rebind: " + name);
        checkAccess("Registry.rebind");
        bindings.put(name, obj);
     * Returns an array of the names bound in the registry.
     * @return An array of the names bound in the registry.
    public String[] list() throws RemoteException {
        String[] names;
        synchronized(bindings) {
            int i = bindings.size();
            names = new String;
Enumeration e = bindings.keys();
while(--i >= 0)
names[i] = (String)e.nextElement();
return names;
* TO-DO
public static void checkAccess(String s) throws AccessException {
// check if s is in the list of agents.
if(true)
else
throw new AccessException("");
public static ObjID getID() {
return id;

You don't have any need to understand this code. The complication is due to the registry needing a fixed objectID.
You just need to know the methods of java.rmi.registry.LocateRegistry class. This allows you to start an RMI Registry inside your JVM and give it any TCP port number you like.

Simple question about java.rmi.registry.Registry

Hi,
where the object java.rmi.registry.Registry takes a URL to rmiregistry when perform bind method.
thanks.

Ok, will try to explain.
I have a server that I register in the RMI registry. Client from a remote machine get the server (as a remote object) and calls his method for the generation of another object on the parameters passed. The server creates this object and tries to register it in the RMI registry, and this raises an exception Registry.Registry.rebind disallowed; origin /11.0.10.31 is non-local host.
11.0.10.31 is a IP - address of the client

Bind to RMI registry on remote host

Is it possible to bing to a RMI registry on remote host. I get a Access exception when I try it. Is there is any work around for this?
Any help will be greatly appreciated.
Thanks
R

:Like I say, JINI uses a different model to RMI, and you can probably have a look at the forum for that here.
but a way around it is to create a server which listens for requests, accepts a remote object and a remote object name, and binds those into the registry on which its running - remember that the restriction only applies to registering objects, not to looking them up, so, once the object is registered on the remote host, it can be retrieved quite easily.
This of course leaves the problem of exception ahandling aside, but I trust the problems there are obvious

Is the RMI registry "process-atomic"?

Hi,
Sorry if this is a really stupid question, and I have really tried to find this out on my own.
When I say "process" I mean Process, as opposed to Thread.
What I mean is, if one Process calls Registry.bind( String, Remote ), can we be sure that another Process which does the same thing one nanosecond later will get an AlreadyBoundException if it calls with the same String?
The context is that up to now I have been starting the RMI Server (only for logging at the mo, these are my first steps) explicitly in a Process. But now I want to move to "lazy" startup of the RMI registry and of the Server... so I would go LoggerInterface.log( bindingName, message ), and if the name "bindingName" is not presently in the registry it will create a new Server, and log the message using it.
More specifically, this is about me trying to automate OpenOffice apps using Java... and it occurs to me that 2 events could indeed happen almost simultaneously, so in fact even explicitly starting up the Server in each handler module might encounter "Process concurrency" problems ... so I need to have an answer to this.
I hope the answer is yes... otherwise I'm going to be a bit flummoxed about how to ensure one doesn't start up one Server Process from one calling Process, and another Server Process from another calling Process.
Thanks

I mean to use rebind() instead of the lookup()/bind() pair. It is atomic.... I understand it is atomic, but my point is that between checking whether you need to rebind (because the bound stub is invalid) and actually doing the rebind there will be an interval. If you systematically use rebind, without a prior check to make sure your Remote is actually attached to an existing Process, every call will cause a new Server Process to be created and then rebound, one after another. Which would be a mess.
I'm going to spend a bit of time looking at your two references... thanks for them.
I have thought of a possible solution involving a sort of lock, but I'm not sure if it works.
1. create a "DummyInterface" extending Remote:
public interface DummyInterface extends Remote {
}2. in the Process + Thread which actually sets up the Registry, bind a DummyInterface
Registry reg = null;
try {
reg = LocateRegistry.createRegistry( 1099 );
} catch (RemoteException e) {
return; // is this right? see below...
DummyInterface dummyStub = new DummyInterface(){};
try {
dummyStub = (DummyInterface) UnicastRemoteObject.exportObject( dummyStub, 0);
} catch (RemoteException e) {
// TODO sthg
e.printStackTrace();
try {
reg.bind( "DummyLockForLoggerServer", dummyStub );
} catch (AlreadyBoundException e) {
// every Thread in every Process (except the first such) to call "bind" will get here
return;
} catch (Exception e) {
// TODO sthg
e.printStackTrace();
}3.     the first Process + Thread which wants to set up the LoggerServer will have first to unbind the DummyLock.
try {
   reg.unbind( "DummyLockForLoggerServer" );
} catch (AccessException e) {
   // TODO sthg
   e.printStackTrace();
} catch (RemoteException e) {
   // TODO sthg
   e.printStackTrace();
} catch (NotBoundException e) {
// every Thread in every Process (except the first such) to call "unbind" will get here
return;
// only one Thread in one Process will ever succeed in getting here
// start the LoggerServer
String qualifiedClassName = ".... rmi.LoggerServer";
String[] a_commandArgs = { "java", qualifiedClassName, "logName" };
Process process = null;
try {
process = Utils.runSubprocess(a_commandArgs, null, ProcessSettings.getJavaRootDir());
} catch (IOException e) {
   // TODO sthg
   e.printStackTrace();
}... however there seem to be one or two questions about this:
- does reg = LocateRegistry.createRegistry( 1099 ); throw a RemoteException if the Registry is already bound? I don't know and intend to do a few experiments to find this out for myself. But in any event only one Process+Thread can ever bind the dummy lock
- there might be a race condition nonetheless to do with the interval between creating the Registry and binding the dummy lock... during this interval the Registry is established, and the dummylock is not yet set up... but I think this does no harm, as a Process trying to start the LoggerServer during this time will get the "NotBoundException" and simply return (and the calling thread will then sleep for a bit before trying again).

Memory leak in RMI registry ? (JRE 1.3.1_11)

Hello. I have a CLI that creates a server which calls some JNI to get
objects for a flat file database and return them. Each time I run the CLI I create a new server and bind it the RMI registry. I created a script that excecutes
the CLI in a forever loop. While this is running I notice the RMI registry program
slowly grows over time until it uses all of the system resources. I keep track of the
servers I create in a Vector and remove them once they are complete. I don't
explicitly remove them from the RMI registry because I assume they would get
garbage collected once all references to them where gone. Has anyone seen
this behavior ? Any ideas what could be happening ? Thanks.
BTW - I am running on Solaris.

The only way out of the RMI Registry is the unbind() method.
If you never unbind anything from the RMI REgistry and keep adding bindings it will grow forever.
You've got your implementation back to front. If you unbind from the Registry then allow DGC to take its course your server will eventually get an Unreferenced callback, which is the signal to remove it from local storage. Alternatively you could just unbind() and remove from local storage immediately. To be frank I am amazed that you didn't try this before posting here.

RMI Registry as a service.

I have found evidence that supports the possibility of rmiregistry.exe running as a service on windows, but I have not found any "How-To" for it. I wrote a batch file to run the command:
sc create "RMI Registry" binpath= "c:\Program Files\Java\jdk1.6.0_03\jre\bin\rmiregistry.exe" displayname= "RMI Registry" start= "auto"
However, when I attempt to start the service, I get the message:
ERROR 1053: The service did not respond to the start or control request in a timely fashion.
Where did I go wrong or is it just not possible?

Do some searching in this forum and you may find some more leads. Also: try hard to google for it.
The registry exe simply does not have the interfacing required to act as a service.
So what most people do is try to write or obtain a service wrapper that can talk to/be controlled by the service manager, and which can also run the registry exe as another process.

Port 1099 being used by other processes ,need an alt port for RMI-Registry

I am using port 1099 for RMI and the o/s is windows 2003.
We want that the RMI registry shud automatically be started with the windows startup processes.But we found that some other processes are usoing the same port.
Is there any other port which can be used for the same?
or any method to make other processes release the port forcefully.

If you read the documentation or do a quick google search, you will discover the rmiregistry program can be assigned any port you wish. Simply invoke via:
rmiregistry -h from windows or "man rmiregistry" from mac or unix and you will be greeted with:
Usage: rmiregistry <options> <port>
In a nut shell just specify the port:
i.e.
rmiregistry 5000
etc...
Hope this helps.
-Lemont

Error in re-creating RMI registry when reloading Tomcat server.

Hi,
I use LocateRegistry.createRegistry() in a servlet which is load-on-startup. I've unexport the registered remote object in the HttpServlet.destroy().
But when I reload the tomcat server, such an exception ocurrs:
java.rmi.server.ExportException: internal error: ObjID already in use
        at sun.rmi.transport.ObjectTable.putTarget(ObjectTable.java:168)
        at sun.rmi.transport.Transport.exportObject(Transport.java:69)
        at sun.rmi.transport.tcp.TCPTransport.exportObject(TCPTransport.java:190)
        at sun.rmi.transport.tcp.TCPEndpoint.exportObject(TCPEndpoint.java:382)
        at sun.rmi.transport.LiveRef.exportObject(LiveRef.java:116)
        at sun.rmi.server.UnicastServerRef.exportObject(UnicastServerRef.java:145)
        at sun.rmi.registry.RegistryImpl.setup(RegistryImpl.java:92)
        at sun.rmi.registry.RegistryImpl.<init>(RegistryImpl.java:78)
        at java.rmi.registry.LocateRegistry.createRegistry(LocateRegistry.java:164)
        at RmiUtils.rebindLocal(RmiUtils.java:86)Here is the binding code in RmiUtils.rebindLocal:
        try {
            Naming.rebind(url, rmiImpl);
        } catch (RemoteException ce) {
            if (!ru.isLocalhost()) {
                ce.printStackTrace();
                // cannot cache
                return;
            } else {
                // try to create the registry in local machine if not created
                try {
                    LocateRegistry.createRegistry(ru.getPort());
                    Naming.rebind(url, rmiImpl);
                } catch (RemoteException e) {
                    System.err.println("Failure in create Registry on port "
                            + ru.getPort() + ", maybe it's been created already!");
                    e.printStackTrace();// handle exception
        }Can anybody help?
Thanks.

Hi
I havent code for quite a while.
I would think that this wont work.
The registry is created on startup (possibly init method in ur servlet) but it is never destroyed.
You are better off starting the registry externally to ur servlet engine, and then use do a bind/rebind on startup, unbind on destroy.
Hope this helps.

RMI registry inside tomcat

Hello,
I'm wondering if any of you have previous experiences in the following situation.
I have a linux server with tomcat 5.0.28 that is supposed to act as an RMI end point for clients connecting with the aforementioned RMI to do some persisting stuff. Now I figured that the easiest way is to create a servlet that creates the RMI registry and binds my server objects (so that's in the servlet's init(), with 1 load-on-startup, the servlet doesn't do anything else, at least yet).
Now problems arise: my linux server is logging "context is read-only" when trying to bind the objects to RMI. Testing on my windows laptop doesn't show the same error for some reason (although it doesn't work properly either). This is apparently normal, as the contexts are supposed to be read-only.
Thing is, I wouldn't want to run a separate rmiregistry on the server, if possible to do it with a simple servlet. But is this the easiest way?
Thank you in advance,
yours truly, in sickness and in health,
Jussi

'Context is read-only' is not a Registry error
message. You are trying to bind to something else.
Show us some code.Well, I'm not doing a lot of binding, so I'm assuming it's this part:
               DDBServer stub = (DDBServer)UnicastRemoteObject.exportObject(this, 0);
               Registry registry = LocateRegistry.getRegistry();
               registry.rebind("DDBServer", stub);The error message is:
2007-04-18 14:06:40 NamingContextListener[Catalina/localhost/DDBServer]: Creation of the naming context failed: javax.naming.NamingException: Context is read only

Some basic questions about rmi registry context "bind" and "lookup"

We have more processing to do than can be accomplished with a single computer. To solve the problem I've implemented a distributed computing solution using RMI. (The first time I saw RMI was about 2 weeks ago, so please bear with me!)
The implementation is a proof of concept not a fully fleshed out system. I have one "Workunit Distributor" computer and any number of "Data Processor" computers all on the same lan segment. "Workunit Distributor" and "Data Processor" computers are both RMI client and server to each other. The "Data Processor" computers are given the ip address and name of the "Data Distributor" on the commandline when they start. They communicate their willingness to receive and process a workunit to the ""Workunit Distributor" via a RMI call. Work units are sent to available "DataProcessors" and results are eventually returned to the "WorkunitDistributor" (minutes or hours later). The model program works quite well, and appears to be capable of doing the processing we need to get done.
But now that it seems viable, I've been asked to make it a little more scalable, flexible and self configuring. In particular, instead of one "Workunit Distributor", any number of "Workunit Distributors" should be allowed to show up or disappear from the lan at any time and the system should continue to function. I've worked out a good scheme for how this can be done, but I have a couple of questions about the RMI registry (registries?). I'm trying to keep from implementing some functionality that may already be available as a library or subsystem.
With my current model design, each computer binds to its own registry with a unique name. For instance:
CRDataProcessorImpl crdpi = new CRDataProcessorImpl(svr);
Context crDataProcessingContext = new InitialContext();
crDataProcessingContext.bind("rmi:"+hostName, crdpi);
Currently the "Data Processors" get the info they need for a Context lookup() of the one and only "Workunit Distributor" from the commandline. And the info the "Workunit Distributor" needs to do a Context lookup() of a "DataProcessor" is passed to it from each "DataProcessor" via a RMI call.
But in the newer (yet to be implemented) scheme where any and all "Workunit Distributors" show up and disappear whenever they feel like, the naming bootstrapping scheme described above won't work.
I can imagine a few ways of solving this problem. For instance, having "Workunit Distributors" multicast their contact information on the lan and have a worker thread on each "Data Processor" keep track of the naming information that was multicast. Another alternative (more organized, but more complex) might be to have a dedicated host with a "well known" address and port that "Workunit Distributors" and "Data Processors" could all go to, to register or look up at an application level. Sort of a "domain name service" for RMI. But both these schemes look like a lot of work to implement , debug and maintain.
The BEST thing would be if there was one plain vanilla RMI registry that was usable by all RMI enabled computers instead of having each computer have its own local name registry. In volume 2 of the Core Java2 book it says that every registry must be local. I'm only hoping there's been progress since the book was published and now a central rmi registry is available.
If you have any ideas about this I'd like to hear what you know.
Thanks in advance for any advice.
Lenny Wintfeld
ps - I don't believe web services, as full featured as it is, is a useful alternative. I'm moving 100's (in the future possibly 1000's) of megabytes back an forth for processing.

The local bind/rebind/unbind restriction is still there and it will always be there.
I would look at
(a) RMI/IIOP, where you use COSNaming as a registry, which doesn't have that registriction, and which also has location-independent object identifiers
(b) Jini.

Shutting down a RMI registry programmatically

If I start up a RMI registry in my code using the following:
Registry reg = LocateRegistry.createRegistry(port);How do I shut it down programmatically? I did a scan on the Registry api and did not find a suitable method. I am looking for a method like close() in ServerSocket to stop listening on a port.

UnicastRemoteObject.unexportObject(reg, true).
This will only work if 'reg' is still the same object returned by LocateRegistry.createRegistry(). It won't work on a result of LocateRegistry.getRegistry() (because that is a stub, not the actual remote object).

Binding to RMI registry on remote host

Is it possible to bing to a RMI registry on remote host. I get a Access exception when I try it. Is there is any work around for this?
Any help will be greatly appreciated.
Thanks
R

This is the same problem I ran into. Unfortunately there is no way around this. I had to abondon using RMI registry and instead I changed my program to use the tnameserv/orbd stand-alone naming services in a typical JNDI fashion. This tutorial has some examples, good luck:
http://java.sun.com/j2se/1.4.1/docs/guide/rmi-iiop/tutorial.html

RMI Registry fail to initiate

Hi Guruz,
Let me describe the problem..
I have 2 apps running on tomcat server. Both the apps initiates RMI server and then regiter the object on RMI registry. If I deploy both the app on a single web server ( Tomcat ) and start the server, it successfully create and register the rmi object but the subsequent app when attempts to register their object, it crashes.
I am pasting the snippet of code that initiate rmi regitry.I am using the same code to initiate rmi registry with the same port.
try{
//Start the RMI registry
registry = LocateRegistry.createRegistry(ServiceProperties.rmiServerBindPort);
catch(RemoteException re){
try {
registry = LocateRegistry.getRegistry(ServiceProperties.rmiAppHost, ServiceProperties.rmiServerBindPort);
} catch (RemoteException remE) {
log.error("could not initialize RMI registry", remE);
throw remE;
Here's the error that is being thrown if subscequent app try to initiate rmi registry. Both the apps have same security policy present. Please give you input why this is happening.
ERROR : remote exception.....Failed to bind to RMI registry : RemoteException occurred in server thread; nested exception is:
java.rmi.UnmarshalException: error unmarshalling arguments; nested exception is:
java.lang.ClassNotFoundException: com.abc.efg.hij.RMIListenerImpl_Stub (no security manager: RMI class loader disabled)
Regards,
Kashif

You can only run one rmi on a single port. You are going to have to use different machines or different ports. How would java be able to distinguish which registry to use if this were possible?

Binding RMI-IIOP Remote Object in RMI Registry through JNDI

hi friends
I am writing RMI-IIOP Remote Object, both server program, and client program
are java programs. Through JNDI (with cosnaming name service), my program is working.
But what i want is, I want to use JNDI (with rmi registry name service) for my RMI-IIOP Remote Object ( and not RMI -JRMP Remote Object). Both my server
program and client programs are java(and not corba)
I am not getting this, while starting server its showing some error
Is it not possible to bind rmi-iiop remote object in rmi registry through jndi, why

because you are supposed to use the COSNaming service with IIOP. Even if you could bind an IIOP remote object into an RMIRegistry the clients wouldn't be able to use it because the RMI Registry doesn't do the extra processing that the COSNaming service does with IIOP references.

RMI Registry leaves thread running

I've searched the postings about this topic and none of them have been helpful. I create an RMI registry at port 1099 in my app, use it, and then try to shut it down, but it leaves a thread running.
The following sample code shows what my code does (in a condensed form):
Registry registry = LocateRegistry.createRegistry(1099);
Communicator c = new CommunicatorImpl();
registry.rebind("//localhost/remoteserver", c );
Naming.rebind("rmi://localhost:1099/TriggerService", c);
registry.unbind("//localhost/remoteserver");
Naming.unbind("rmi://localhost:1099/TriggerService");
boolean b = UnicastRemoteObject.unexportObject(registry, true);
System.err.println( "unexported: "+b );When I run this code in Eclipse and the code exits, I still have a process running that was spawned by "LocateRegistry.createRegistry(1099)", but I can't figure out how to get a handle for it within my program, so that I can kill it. I've read that it will end when the JVM ends, but the RMI portion of my app is only a small part and I need the rest of it to keep running. Is there a way to stop this thread?
Thanks,
Tony

Well I only see 'createRegistry' and 'getRegistry' I don't see any 'destroyRegistry' methods. So I don't know.
What I used to do back in the day was to use Runtime to start an external process for processes that I needed to kill later on. So perhaps you can use the runtime to start the registry from the command line so to speak. Then hold a reference to the returned process. Then you can kill that process when you want the registry to die. In this case you will for sure be creating a new 'jvm' for the registry to run within. (if the registry is a java program)
Otherwise I have no idea why you would be seeing an extra java process. If you run the eclipse debugger, the debugger should not exit until the whole process is done. Even when the program is done, the debugger will still be 'live' and you can push the stop button to stop the whole launched process.

RMI Registry

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