RMI server and client in one application - Exceptions during some calls

I wrote an application, which is an RMI-Server (Server1), and another separate application, which is an RMI-Client (Client1). Because I wont use dynamic class loading, I gave the client beside the interface.java also an interface_implementation.java, which is only a dummy of the original interface_implementation of the server. This dummy contains only declarations of the methods (parameters and return values) and no functional code. From this dummy the _stub.class is generated, and it works fine - no problem.
Now I want to modify Client1 to become also an RMI-Server (Server2) for a second, separate Client (Client2), the methods used are different from the first RMI connection. This Client2 uses a dummy of the implementation of Server2 in the same way as described above. The application Client1+Server2 only has to "translate" the calls from Client2 to Server2 into calls of Client1 to Server1 (Server1 is not changed at all). In case of primitive method parameters or return values this chain of RMI-applications works fine, but in case of more complex structures (my own classes) during the call of Client1 to Server1 an "ClassNotFoundException: access denied to class loader" occurs by running through the stub. Both stub.classes are found, all of the applications know the objects needed, the call of Client1 to Server1 is exactly the same call as it was during the simple version (only Server1 and Client1).
Does anybody know, why this exception occurs and how I can overcome this ?
Axel

I figured out a solution - it's a problem of policies. In detail: Server1's codebase entry (file:) refers to the class directory of Server1's project. In the simple case of only Client1, which has no codebase entry, it works fine without a file permission on the side of Server1. In the complex case of Client1+Server2, which has to have a codebase entry (file:) refering to the class directory of the Server2's project on a separate machine, for exactly the same method call from Client1 to Server1 a file permission entry on the side of Server1 is needed for Server1's class directory. But WHY ???
It seems to be a little confusing with the codebase entries, many of the posts are contrary to others and to my personal experiences. Some comments given by Adrian Colley throw a little light upon some aspects. Is there anybody, who can explain the whole topic, when, why, and which part of RMI application deals with codebase entries, also in case of not dynamic code downloading ? May be there is also a reference into the java docs, which I didn't found up to now.
Thanks in advance
Axel

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Can I put both RMI server and client in a same program

hi everybody...
I wanna know that can I use RMI server and client in a same program....My idea is like that I wanna use the same program for client and server....When I open my program, I can accept connection from other program and if I want to connect to others, I can also connect it. I expect you to understand my question. Here are the sample code for my program...
package Chat.Rmi;
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Yes it can be done. I have done it.

RMI Server and RMI Client Problem

First, Hi!
I have create my RMI Server and a RMI Servlet client.
I can run the server and servlet first time and it works fine.
Then, I stop rmiregistry and server.
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java.rmi.ConnectException: Connection refused to host: xxx.xxx.xxx.xxx; nested exception is: java.net.ConnectException: Connection refused
If I copy the class again where the servlets resides, it works again. But I have to keep doing that. I have to keep copying the class file to the servlet directory every 2nd time I try to run it for it to work.
Anyone know what am I doing wrong?

First, Hi!
I have create my RMI Server and a RMI Servlet client.
I can run the server and servlet first time and it
works fine.
Then, I stop rmiregistry and server.
Then, I start rmiregistry and server for a second time
but my RMI Servlet client gets a
java.rmi.ConnectException: Connection refused to host:
xxx.xxx.xxx.xxx; nested exception is:
java.net.ConnectException: Connection refused
If I copy the class again where the servlets resides,which class file ? u mean RMIServer's class files ??
I have faced the same problem too. In my case if i just restart my Tomcat webserver the error goes and the servlet is very well able to connect back to the RMI Server
it works again. But I have to keep doing that. I have
to keep copying the class file to the servlet
directory every 2nd time I try to run it for it to
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Try to use one comupter as both server and client

Hello, everyone, I am just trying to use my own computer as both server and client to test some codes about networking. For example, use the sample code in java tutorial which is used to test Echo server(code is listed below). Is there anything I have to do to set my computer, such as set my hostname or something like that?
I am a pure newbie. And the purpose of this question is to test some code including socket on one PC without connect to internet.
I have tried to change the name "taranis" in the following code to the computer name of my own PC, but it doesn't work, and said: Couldn't get I/O for the connection to: (my computer name).
import java.io.*;
import java.net.*;
public class EchoClient {
public static void main(String[] args) throws IOException {
Socket echoSocket = null;
PrintWriter out = null;
BufferedReader in = null;
try {
echoSocket = new Socket("taranis", 7);
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in = new BufferedReader(new InputStreamReader(
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Did you write the EchoServer and start it on your
machine, listening on port 7?
You can have the client and server running on the same
machine or different machines, but they have to be
separate pieces of software.
Write a separate EchoServer class that starts up and
listens on that port. Then start the EchoClient and
make the connection.
%yeah, I didn't wrote the EchoServer class. But I thought it is automaticly included and therefore has run once I start my computer.
If I write a EchoServer class, then how should I set the host name of the EchoClient, just simply change "taranis" to my computer name (change "echoSocket = new Socket("taranis", 7);" to echoSocket = new Socket("(my comptuer name)", 7);"?

How can a VI be both server and client?

Hi,
I'm new in LabView and I'm trying to build a server and client VI using TCP/IP that runs in two computers. in my program I need both server and client VIs to communicate with each other which means I need both VIs to be server and client. I've tried using a case structure but it doesnt work. The only thing I achieved is a normal server/client system where the server sends a request and the client responses.But i need the client to send requests too.i have attached my VIs to this post.I would appriciate it if someone could help with this problem.
Thanks in advanced.
Rambaldi.
Solved!
Go to Solution.
Attachments:
Server-Client.zip ‏41 KB

Do you really need a client and server on each PC? If you simply need that two to talk to each other they can once the client connects to the server. In most cases you only need one server.
What Steve said about the not using the same port only applies to two servers on the same machine. A client must use the port the server is listening to and if the client and the server are on the same machine then they will both use the same port. However, only ONE of them is accepting waiting for connections on that port.
In the code you posted you actually swapped the names. What you call the client is actually the server code and vise versa. In networking a server is an application that listens to an assigned port, accepts connections on that port and provides whatever services it has implemented. A client is an application that establishs a connection to a server. Once a connection is established the two applications can communicate in both directions. The applications themselves will define how the conversation should progress and whether it is a one way conversation or a two way conversation. You don't specify what you are trying to accomplish but I suspect you only need a single server.
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OK, end of networking 101.
Can you describe in a bit more detail what exactly you want to accomplish. Given that I could probably provide you with more information for your application.
Mark Yedinak
"Does anyone know where the love of God goes when the waves turn the minutes to hours?"
Wreck of the Edmund Fitzgerald - Gordon Lightfoot

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I figured out a solution - it's a problem of policies. In detail: Server1's codebase entry (file:) refers to the class directory of Server1's project. In the simple case of only Client1, which has no codebase entry, it works fine without a file permission on the side of Server1. In the complex case of Client1+Server2, which has to have a codebase entry (file:) refering to the class directory of the Server2's project on a separate machine, for exactly the same method call from Client1 to Server1 a file permission entry on the side of Server1 is needed for Server1's class directory. But WHY ???
It seems to be a little confusing with the codebase entries, many of the posts are contrary to others and to my personal experiences. Some comments given by Adrian Colley throw a little light upon some aspects. Is there anybody, who can explain the whole topic, when, why, and which part of RMI application deals with codebase entries, also in case of not dynamic code downloading ? May be there is also a reference into the java docs, which I didn't found up to now.
Thanks in advance
Axel

I am using server and client systems when i am trying to open the browser in two or more machines it says that firefox is already running, i want to open the browser in all machines simeltaniously

I am using server and clients machines in my office, here i want to open browsers in all systems simultaneously but i am unable open the browser, when i am trying to open the browser in the second machine it says that firefox is already open... pls. solve this problem
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br
ralf
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The correct property is a java system property:
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Hello,
our Volume License Manager (v2.1) is running in another subnets than the clients (All machines are running under Windows XP-SP2 without Domains or ADS, just workgroups).
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Hello Thorsten,
Did you add the server's domain to the client computer's DNS settings. To do this, complete the following steps on the client computer:
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Why is My NI License Manager Slow or Not Responsive with a Configured Network Server on Another Domain?
http://digital.ni.com/public.nsf/allkb/27D6BD8116EF257A862572F2005C2181?OpenDocument
How Can I Access NI Volume License Manager from a Different Network or Behind a Firewall?
http://digital.ni.com/public.nsf/websearch/54E52C3F348B929786256DCD0056B19B?OpenDocument
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===========
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Hello there
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Attachments:
Client Remote.vi ‏746 KB
Server Remote.vi ‏1433 KB

Hi ican,
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National Instruments

RMI server and client in one application - Exceptions during some calls

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