Skeleton and Stub

Why do we need Skeleton and Stub?What are their functions?
Thanx in Adv

Hi,
with JDK 1.3 you need no Skeleton anymore.
The stub is a proxy on the client side which
organizes the communication with the RMI server
on the remote host. It exposes the same remote
interface as the remote server and passes the client's
RMI calls over the network.
Have fun,
wiedkla

Similar Messages

RMI skeleton and stubs

Hi,
I'm studying RMI and have been reading a book. In the book they speak about having to generate a stub and a skeleton class.
However, I also did the exercise on the site below and it seems it worked fine, without having to create a stub or skeleton. http://java.sun.com/docs/books/tutorial/rmi/overview.html
Can anyone explain please???
Thanks

in fact, i don't understand the paragraph below on the site:
"Later, in JDK 1.2, the skeletons were incorporated into the server itself so that there are no separate entities as skeletons. In other words, the skeletons's functionality was incorporated into the server itself. So, the scenario became like this:
Client<--->stub<--->[NETWORK]<--->Server_with_skeleton_functionality"
how does it works then????
i understand the concept with stubs and skeletons well, but now that skeletons are not needed anymore, i'm a bit lost....
you can just indicate a class to extend "remote", and then compile it with javac ?
from then on the remote class file can remotely be called???
right???

EJB Home Objects and Stubs

Hi,
Can anyone pls tell me,what are the objects are created in Server after the Deployment of EJB.
Is the EJB Home Object,EJB Home Object Stub,EJB Home Object Skeleton, EJB Local Home Object, EJB LocalHome Object Stub,Ejb LocalHome Object Skeleton.And Finally both the Stub objects and Skeleton Objects will be stored in the Jndi Registry ?
Thanks in Advance,
Venkat

Nic,
Caching the home object is a comon practice.
Take a look here:
http://www.theserverside.com/resources/patterns_review.jsp
Look at the EJB Home Factory Pattern.
Regards,
-Dat

How to make a check and stub using print/println statements

ok...after all the great help i've gotten from people here.
i need some help, again :)
i have to print out a paycheck and stub to look like this (it's on my clan's counterstrike forums because i can't find out how to host it on this site and i dunno my PW to photobucket)
http://www.cause4alarm.net/index.php?showtopic=2436
it should let anyone view it, if not tell me and i'll figure out somewhere to host it.
i need to know how to print out the x's around the sections, and how to put the info into those specific areas....i'm kind of asking a lot, i know. You can point me to a link that explains this sort of stuff or do it for me (i'd REALLY like that lol) or explain it yourself, i don't care. i have 2 hours and 25 minutes until i would like to go to bed, but i can always stay up longer if need be. I'll be looking in my book and on google as well.

Cant view the image b/c I am not a member of that forum.
However, look into String's format() method. It's probly what you're lookin for to making print statements line up nicely however you want them.

Mocking and Stubbing in Java - (JUnit, etc)

Currently our junit tests all eventualy read the database to fill the objects and test code.
My question is, isnt it a better practice to mock/stub and avoid the trip to the database, since we are testing the logic, not the database connection?
But if my thought is right on mocking and stubbing, how can it be made possible?
For example. Lets say I have class foo which calls dataHandler.java which in turn called dataAccessor.java. There is no way that I know of that inside the foo class we could tell the dataHandler class to override the dataAccessor class and instead of using that dataAccessor which calls the database, use another class such as dataAccessorForUnitTesting and inside that class simply fill the requested object with dummy data and return it. Basically saying foo cannot override a class thats multilpe levels deep.
Just looking for some suggestions on people who use testing such as junit. If the right way is to read the database, then so be it. I'd just like someone to point that out from their experience.

georgemc wrote:
r035198x wrote:
georgemc wrote:
r035198x wrote:
See if integrating with Jmock helps.What does that even mean?Well with jmock you can mock out method calls and let them return test data so you don't have to go to the DB for your test cases.Yes, I know what JMock does, I just don't see that that's "integrating" with it. Isn't it just "using" JMock?
@OP: if you're looking for a mocking library, there are far better ones than JMock around. Mockito is nice, for example. Or Powermock.Ah, the meaning was integrating it with JUnit (perhaps better plugging it into JUnit).
I've only ever used JMock and will definitely try the ones you mentioned to be better.

Different OPCODE's between tie and stub

Hello
I am using wscompile to generate both server and client classes for a web service. Of course I am using the appropriate "-gen:server" and "-gen:client" options for each call.
The problem is that operations OPCODE's are different between the Tie and Stub classes. When I call operation "A", the outbound request OPCODE is set to 0 (zero), which corresponds to operation "B" when interpreting the inbound message on the server.
How can I solve this ?

The error you mentioned literally means "connection lost", which could mean the site is temporarily down, or the server is overloaded. It will usually resolve itself in time. But if the PPC Macs can't open those sites and the Intel Macs can at the exact same time, there must be some other factor involved.
When you report things to Apple, they do not respond to you, so don't expect that. There are other things you could try to see if they resolve the problem, though I tend to doubt it:
1. Quit Safari if it's running.
2. Go to Home/Library/Caches/Safari and delete all the sub-folders within that one.
3. Go to Home/Library/Safari and delete any of these files that you have there:
• Downloads.plist
• Form Values.plist
• History.plist
• LastSession.plist
4. Restart Safari and see if that makes any difference.
Mulder

What relationship between RMI interface and stub?

Hi:
I think the stub is enough to remote call, why to use RMI interface? what relationship
between RMI interface and stub?
Regards!
Stive

Hi,
Stub is merely a proxy for server , it doesn't contain any declarations of
remote methods. to which it is being responsible for .
where RMI interface is one which contains signature of the Remote methods which
throws Remote Exception.
Regards
Karthikeyan Gangadharan
SIP Technologies, Chennai
E-mail-ID: [email protected]
"Stive" <[email protected]> wrote:
>
Hi:
I think the stub is enough to remote call, why to use RMI interface?
what relationship
between RMI interface and stub?
Regards!
Stive

RMI, stubs and skeleton and EJB

HI,
IN RMI we copy stub on client machine and skeleton on Server machine.
EJBs are said to be extension of RMI.
In EJB when we deploy EJB on the app Server server generates stubs and skeleton.
But on the client machine we don't copy any stub.
So from where these stubs (home stub and remote stub ) comes on client machine because we only depoly the EJB at server and then use that from client
Can anybody explain this ?
Thanks,
Ankur Mittal

Hi,
A number of these answers are correct. The thing to keep in mind is that the entire issue of RMI stubs and the mechanism by which those stubs are made available to the runtime code(whether that code is running in a J2EE server or a client) is vendor-specific. One important thing to note is that these generated artifacts are not present in a portable J2EE archive (.ear, ejb-jar, .war, etc.)
If needed, they are generated at some point by the J2EE implementation. Some vendors expose tools that generate these artifacts. The original J2EE 1.4 SDK beta release had such a tool called j2eec.
Alternatively, many vendors generate them as part of the deployment stage itself. In that case, it's typical for the deployment process to produce some output file that contains the generated artifacts. This is the approach used in the current J2EE 1.4 SDK. The output file is usually referred to as a client.jar. The stubs are automatically available to any code running within the server, but client applications that need them must somehow make the client.jar available to the client JVM. For Application Clients, this is done by specifying the client.jar as one of the input arguments to the runclient command. For stand-alone clients, the client.jar is simply added to the user-classpath when starting the JVM.
Some vendors also support automatic stub-downloading. This has the advantage that the stubs don't have to be available to the client classpath when the client starts. The downside is that using automatic stub downloading requires that a security manager be installed in the client JVM. That typically isn't an issue for the Application Client container, but many stand-alone clients are not coded to instantiate a security manager.
Yet another approach is to dynamically generate the stubs within the client code itself. This is one of the best options since it completely removes the notion of stubs from the developer's view. It's too bad this wasn't done from the beginning, since stub configuration is one of the most common errors encountered by EJB developers. In addition, the static generation of such artifacts is often a deployment-time bottleneck. Finally, note that the EJB Remote view is only one of many J2EE technologies that potentially require such generated artifacts. E.g., web services implementations typically rely on some of the same mechanisms to marshall and unmarshall requests.
--ken
Kenneth Saks
J2EE SDK Engineering
SUN Microsystems

RMI and stub

i have an ServerIfc.java which is an interface for the RMI (and extends the Remote object) , and ServerImpl.java which is an implemmentation of the ServerIfc.java interface.
when i execute the rmic command i got ServerImpl_stub.class.
My question is , if any change in the ServerImpl.java (e.g add System.out) will cause the ServerImpl_stub.class to be changed too? does the ServerImpl_stub.class will be changed only if the ServerIfc.java will be changed??

I think yes. If you change anything in the interface's implementation the generated stubs and/or skeletons will change too.
If you change the interface, your implementation-class should change as well. That is quite obvious. Thus, your stubs and skellies will change as well after you've compiled with rmic.
This question belongs in the RMI forums though...

Dynamic Class Loading and Stubs

How Dynamic Class Loading is used on Java RMI, since stubs are generated on clients using Reflection API?
I was reading Dynamic code downloading using JavaTM RMI (http://java.sun.com/javase/6/docs/technotes/guides/rmi/codebase.html), it seems to be out of date.
For example, "The client requests the class definition from the codebase. The codebase the client uses is the URL that was annotated to the stub instance when the stub class was loaded by the registry. Back in step 1, the annotated stub for the exported object was then registered with the Java RMI registry bound to a name."

"Enhancements in J2SETM 5.0
Dynamic Generation of Stub Classes
This release adds support for the dynamic generation of stub classes at runtime, obviating the need to use the Java(tm) Remote Method Invocation (Java RMI) stub compiler, rmic, to pregenerate stub classes for remote objects. *Note that rmic must still be used to pregenerate stub classes for remote objects that need to support clients running on _earlier versions_.*
When an application exports a remote object (using the constructors or static exportObject methods(1) of the classes java.rmi.server.UnicastRemoteObject or java.rmi.activation.Activatable) and a pregenerated stub class for the remote object's class cannot be loaded, the remote object's stub will be a java.lang.reflect.Proxy instance (whose class is dynamically generated) with a java.rmi.server.RemoteObjectInvocationHandler as its invocation handler.
An existing application can be deployed to use dynamically generated stub classes unconditionally (that is, whether or not pregenerated stub classes exist) by setting the system property java.rmi.server.ignoreStubClasses to "true". If this property is set to "true", pregenerated stub classes are never used.
Notes:
* If a remote object has pre-5.0 clients, that remote object should use a stub class pregenerated with rmic or the client will get an ClassNotFoundException deserializing the remote object's stub. Pre-5.0 clients will not be able to load an instance of a dynamically generated stub class, because such a class contains an instance of RemoteObjectInvocationHandler, which was not available prior to this release.
* Prior to the J2SE 5.0 release, exporting a remote object would throw a java.rmi.StubNotFoundException if the pregenerated stub class for the remote object's class could not be loaded. With the added support for dynamically generated stub classes, exporting a remote object that has no pregenerated stub class will silently succeed instead. A user deploying a server application to support pre-5.0 clients must still make sure to pregenerate stub classes for the server's remote object classes, even though missing stub classes are no longer reported at export time. Such errors will instead be reported to a pre-5.0 client when it deserializes a dynamically generated stub class.
(1) The static method UnicastRemoteObject.exportObject(Remote) is declared to return java.rmi.server.RemoteStub and therefore cannot be used to export a remote object to use a dynamically generated stub class for its stub. An instance of a dynamically generated stub class is a java.lang.reflect.Proxy instance which is not assignable to RemoteStub."
http://java.sun.com/j2se/1.5.0/docs/guide/rmi/relnotes.html

Web Service and Stub-generation with WTK

Hi there,
I hope someone can help me.
I just deployed a webservice using Axis.
WSDL: http://www.freewebs.com/sirpreis/CustomerWS.xml
WSDD (for deployment): http://www.freewebs.com/sirpreis/customerWS-WSDD.xml
The WS deploys fine, but now I want to generate stubs using the WTK stub generator. Unfortunately I get the following warnings:
warning: R2716 WSI-BasicProfile ver. 1.0, namespace attribute not allowed in doc/lit for soapbind:body: "getAccountBalance"
warning: R2716 WSI-BasicProfile ver. 1.0, namespace attribute not allowed in doc/lit for soapbind:body: "getAccountBalance"
I don't know if that will become a problem...
Well now, three classes + src are generated
AuthSet.java/.class
CustomerWS.java/.class
CustomerWS_Stub.java/.class
In my webservice, the method "getAccountBalance" gets an "AuthSet" (which is set up of a String pwd and an int userID) as argument
(public int getAccountBalance(AuthSet auth) throws RemoteException {).
In the CustomerWS_Stub.java now there is a method "getAccountBalance", but it gets the following:
public int getAccountBalance(java.lang.String pwd, int userID) throws java.rmi.RemoteException {
Can anyone help me with that? I don't know what to do :(

Hi,
I think its a problem of your wsdl-File. If you post it, it would be easier to find the problem. The wsdl-file don't provide the WS-I specifications.
Steve

InstallMenu and stub projectors

I am running a movie from a stub projector. The movie uses
pull-down menus made with installMenu. If I set the publish option
in the stub to "full screen", then the menu bar does not appear. If
I don't set it to full screen, then I get the following message:
"Must have either Full Screen or Show Title Bar set to show user
menus." I don't believe that Show Title Bar is an option in
Director 2004MX, at least I can't find it anywhere, and using Full
Screen prevents the menus from appearing. Does anybody know the
answer to this?

> I don't believe that Show Title Bar is an option in
> Director 2004MX, at least I can't find it anywhere
If you open the Property Inspector to the Display Template
tab you could
try checking the "Visible" box under Titlebar Options and see
if that helps

Help for mock web service (service skeleton and unmarshalling)

Hi,
I need to create mock web service in which I want to read soap/xml responses from my hard drive and send it to web service client. The responses would differ based on some input parameter. (small business logic in mock service)
Till now, I created my mock service skeleton from Axis and used JAXB (JWSDP) to unmarshall xml to java objects. But problem is we can not cast object unmarshalled by JAXB into response object created by Axis. And so can not return those objects as response.
So, I want to know if I can use JWSDP or Metro to solve this problem. Will JWSDP or Metro solve my problem if I use it to create service skeleton as well as for unmarshalling?
If this is not possible, can you please suggest any viable alternative?
Regards,
Suraj

surajmundada wrote:
SOAP-UI can provide only one static soap response.Incorrect. Look at the [top 3 reasons|http://www.soapui.org/gettingstarted/mocking.html] from soap-ui. You can use Groovy to add the dynamic functionality in your simulated web service.
And if you don't have the WSDL and you want to simulate the web service. You can use the article [web service simulation using servlet |http://today.java.net/article/2010/02/16/web-service-simulation-using-servlets] to build your own simulator.

RMI skel and Stub

hi,
i am trying to create Stub and skel class files , but i am getting only Stub class , not able to generate skel class. where may be the problem?
i think i will get the solution , in advance i say thanks,
with regards,
kamalahasan

hi kamal,
Dont worry much about Skel class.becoz its of no use since jdk1.2.U need stub if u r using jdk1.4.* and in jdk1.5 you need not have to generate stubs.
cheers
Mandrake

Help me to run this simple RMI example

When i m running this example in standalone pc it works but while running on to different pc it gives error though I m giving the IP address from client of server.. If anyone can help me out plz help.
Code:
ReceiveMessageInterface
import java.rmi.*;
public interface ReceiveMessageInterface extends Remote
void receiveMessage(String x) throws RemoteException;
Server code:
import java.rmi.*;
import java.rmi.registry.*;
import java.rmi.server.*;
import java.net.*;
public class RmiServer extends java.rmi.server.UnicastRemoteObject
implements ReceiveMessageInterface
int thisPort;
String thisAddress;
Registry registry; // rmi registry for lookup the remote objects.
// This method is called from the remote client by the RMI.
// This is the implementation of the �ReceiveMessageInterface�.
public void receiveMessage(String x) throws RemoteException
System.out.println(x);
public RmiServer() throws RemoteException
try{
// get the address of this host.
thisAddress= (InetAddress.getLocalHost()).toString();
catch(Exception e){
throw new RemoteException("can't get inet address.");
thisPort=3232; // this port(registry�s port)
System.out.println("this address="+thisAddress+",port="+thisPort);
try{
// create the registry and bind the name and object.
registry = LocateRegistry.createRegistry( thisPort );
registry.rebind("rmiServer", this);
catch(RemoteException e){
throw e;
static public void main(String args[])
try{
RmiServer s=new RmiServer();
catch (Exception e) {
e.printStackTrace();
System.exit(1);
Client code:
import java.rmi.*;
import java.rmi.registry.*;
import java.net.*;
public class RmiClient
static public void main(String args[])
ReceiveMessageInterface rmiServer;
Registry registry;
String serverAddress=args[0];
String serverPort=args[1];
String text=args[2];
System.out.println("sending "+text+" to "+serverAddress+":"+serverPort);
try{
// get the �registry�
registry=LocateRegistry.getRegistry(
serverAddress,
(new Integer(serverPort)).intValue()
// look up the remote object
rmiServer=
(ReceiveMessageInterface)(registry.lookup("rmiServer"));
// call the remote method
rmiServer.receiveMessage(text);
catch(RemoteException e){
e.printStackTrace();
catch(NotBoundException e){
e.printStackTrace();
}

When we compile with rmic skeleton and stub get created then we hav to place stub at each client ???Your remote client applcation need only _Stub.class fiels.
Is there way by which we can know how many clients are connected to the
server and there IP address, can anyone give the code... I guess that you should use a RMI login/logout method to register/unregister your client connection information into a databse or a simple static Hashtable(Vector) object.

Skeleton and Stub

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