Using multi-thread in RMI
i know how to do a simple RMI program, but now i want to have a multi-threaded server to support the client. could any one tell me how to do this (using Thread in RMI) ??
thx.
Mo
Well, you kind of answered your own question.
An RMI server is inherently multi-threaded. This means that each remote request from a client is a separate thread, and can execute simultaneously with requests from other clients. In fact, your biggest problem will probably be to identify the places where access to objects must be synchronized, so that simultaneous requests do not conflict.
So what is it you have to do that RMI doesn't do?
Similar Messages
-
Using multi threading to access 2 RS232 ports
Hi,
I'm a beginner in multi threading, so this question may be a very basic one....
I'm Using TS3.5 + CVI 8.01 to communicate withs 2 RS232 ports. I thought to use mult threading so I can process 2 steps in parallel rather than in series.
This is what I do:
1) I defined 2 subsequences, each of them call the same CVI function. I use the sub sequence parameters to transfer the com number.
2) My CVI application includes one dll for this specific project and another one, a general dll to handle RS232 functions. The RS232 dll uses one global buffer than collects all the traffic on the com.
QUESTIONS:
1) What happens when 2 seperate threads run the same function in the RS232 dll? (in terms of memory etc...). Does each one use a different buffer (in terms of memory allocation), or, both of them writes to the same buffer? Obviously, if they writes to the same buffer, then, my function will not operate properly.
2) What happens in TestStand after the 2 steps in new threads have finished their execution? does the next step run back in the same threads the sequence run before?
Thanks
RafiRafi,
Glad to hear you were able to make some ground on your application. As for all of your questions, I'll try to answer as many as I can.
First, when you are talking about your global buffer, is it created in TestStand or in the DLL itself? When you use DLLs, global variables or global structures are shared between all threads that call your DLL. On the other hand, if your buffer is declared inside of the DLL it is global for the DLL but not shared and would be a separate buffer for each call.
With your run-time error in TS, it would definitely be helpful to have more information about the error. From what you explained (executing fine on the first call, but failing on future executions), it sounds like the resource is not being released after the first execution.
As far as a specific example for TestStand Multithreading, you'll want to look at the TestStand Development Library and, specifically, Multithreading in TestStand. If you look and browse through the Application Notes and Tutorials section, as well as the Technical Presentations section, you will learn a great deal about multithreading and what options you have in TestStand. For a specific example, you may want to look at This Example. You could also look in the <TestStand>\Examples (where <TestStand> is the directory where TS is installed) at the MultiUUT example for an example of multithreading in TS. These examples may not be exactly what you need, but they should give you a jump start.
As far as making your DLL multithread safe, it is definitely not necessary; however, there are some significant advantages described in this article: Designing Thread-Safe DLLs. It is an MSDN article that focuses on Visual Basic, but it has some helpful information that can apply to C as well.
Hopefully this can help you move further. I have attached a list of links at the end of this post with other helpful links for you as well. Keep us posted with your progress.
Matt Mueller
NI
Links:
General Information on Multithreading for C Programmers
Building Multithreading Applications with LabWindows/CVI
Multithreading in LabWindows/CVI
Easy Multithreading Programming in LabWindows/CVI
Multithreading for Rookies -
How can i use multi threading in labview?
i want to run a Digital storage oscilloscope and an energ ratio meter simultaneously using labview. i am using GPIB interfacing and windows XP. how can i do this using multi threading. Bot the instruments shd run and give data at the same time.
You can't do this - at least not with a single GPIB board. It has nothing to do with threading or LabVIEW. There can only be one talker at a time over the bus. Depending on the instruments, you could probably set them up to take measurements simultaneously but you have to sequentially poll them to get the data.
-
How to use Multi Thread to make a animation
Hello
Currently i am writing a router simulator using Java SE 1.4.2. I am facing a problem that is I cannot use multithread to update my Jframe animation.
Here i give my approach.
My idea is I used a JPanel in JFrame and I used Graphics g draw all background in Jpanel and add it into Jframe. It works since there is no animation invovled. I want to do some animation based on this background which i draw. But all animation should be controled by other threads due to i want other threads can control all animation. But i hit a error which is nullpointexception. The reason looks like which i used another to do animation, it cannot find the reference which is point to the Jpanel and Jframe. May u teach me a correct way to do multi threads animation in Jframe? thanks.
all the best and regards!A simple annimation moving a circle round a screen. This uses a model that defines the dynamics of the annimation, a view to display a visual representation of the model and an event system (observer/observable) to notify the view that the model has changed.
I hope this helps.
import java.awt.*;
import javax.swing.*;
import java.util.*;
public class Test20041023 extends JFrame
public Test20041023()
super("Simple Annimation Demo");
AnnimationModel annimationModel = new AnnimationModel();
AnimationView animationView = new AnimationView(annimationModel);
setContentPane(animationView);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
pack();
private static class AnimationView extends JPanel
private static final int PREFERRED_WIDTH = 512;
private static final int PREFERRED_HEIGHT = 256;
AnimationView(AnnimationModel annimationModel)
// Save a reference to the model for use
// when the view is updated
annimationModel_ = annimationModel;
// Listen for the events indicating that the model has changed
annimationModel_.addObserver(new Observer()
public void update(Observable o, Object arg)
// All we need to do is to get the view to repaint
AnimationView.this.repaint();
public void paintComponent(Graphics g)
super.paintComponent(g);
// Update the view based on the information in the model.
g.setColor(Color.red);
// Convert the model positions to view positions
// in this case by scaling to the actual width and height.
int xScreenPosition = scaleValue(annimationModel_.getX(), getWidth() - 20 ) + 5;
int yScreenPosition = scaleValue(annimationModel_.getY(), getHeight() - 20 ) + 5;
// Display the position of the point
g.fillOval(xScreenPosition, yScreenPosition, 10, 10);
private int scaleValue(double v, double size)
return (int)((v+1.0)*0.5 * size + 0.5);
public Dimension getPreferredSize()
return new Dimension(PREFERRED_WIDTH, PREFERRED_HEIGHT);
// The saved reference to the model
private AnnimationModel annimationModel_;
private static class AnnimationModel extends Observable
AnnimationModel()
Thread annimationThread = new Thread()
public void run()
// Loop forever updating the model
// and notifying the observers.
while(true)
// Wait 0.05 seconds until the next frame update point
try
sleep(50L);
catch (InterruptedException e)
// Nothing to do
// Update the model - in this case it is very simple
theta_ += 0.1;
// Notify the observers
setChanged();
notifyObservers();
annimationThread.start();
// Model access methods
public double getX()
return Math.cos(theta_);
public double getY()
return Math.sin(theta_);
// The angular position of the point
private double theta_;
// Simple test main
static public void main(String[] args)
new Test20041023().setVisible(true);
} -
Performance problem using multi-thread
I am using berkeley db to store a int/double pair, and i randomly get 100,0000 results to check the performance . Using 1 thread, it cost about 1 Mins. But using 4 threads, it costs 4 Mins. More threads, lower performance. Is there Anyone know the reason?
Env flags:
envFlags=DB_CREATE | DB_INIT_MPOOL | DB_THREAD | DB_PRIVATE|DB_INIT_CDB;
DB open flags: DB_THREAD
and i use db->get method to get results.Berkeley DB 4.8 will be released soon and has features that address CMP/SMP scalability. We would appreciate your feedback on your experiences with it. Once available, please test it and post your results here, I'm sure you'll be pleasently surprised.
regards,
-greg -
Using multi-threading: Setting a VI to be used for two sequences at same time
I have two sequences running as two different threads. This is supposed to be in parallel but both sequences access the same VI, then they're not executing as parallel because one sequence use this VI then liberates it and the other sequence use it, and so on consecutively until both sequences finish. This is not what I want.
How can I do to set this VI with any kind of property or something that can be accessed for both sequences at the same time?
Thanks,Hi Margarita, you can set a VI to be reentrant (under VI Setup»Execution Options from TestStand, this function can also be used from LabVIEW) . Now depending on the king of VI you are using this can be something safe or can cause trouble. If the VI needs to keep information (for example a Functional Global Variable) or it is handling Hardware it can give you errors (for example trying to access the same DAQ at the same time from different task.
If you need more information can you tell us what does this VI does?
This Links might also be useful:
When I Run Parallel TestStand Executions That Call the Same VI, Why Don't the VIs Run in Parallel?
Differences Between Reentrant VIs (Preallocate), Reentrant VIs (Share Clones), VI Templates, and Dyn...
Best Regards
Benjamin C
Senior Systems Engineer // CLA // CLED // CTD -
Trouble rationalizing use of multi-threading in run of the mill servlets
Hey everybody,
While spending time writing an internal wiki article on servlets for work, I asked myself a very basic question: What does multi-threading buy average servlets where the business logic requires procedural handling of the request?
Don't get me wrong: I appreciate the fact that servlet containers spawning a new thread being less expensive than spawning an entirely new process is helpful and efficient. Coming from a background in PHP, it is great how servlets maintain persistence. However, as more of my coworkers are required to gain proficiency in Java and designing servlets, it is a question that many will ask and aside from having real-time processing of data files and other arduous tasks, I cannot think of any instances of where multi-threading benefits the application.
What are some of the ways that you are using multi-threading with web applications?
How would you explain why and where you would want to use multi-threading to someone?
Thank you in advance for your insight,
Andyhow can we pass arguments to the run ()method?Create classes which implement Runnable that take your runtime parameters as constructor arguments and store them.
eg: if your single thread method is static void foo (int quantity, String name) {
for (int i=0; i<quantity; i++) {
System.out.println(name);
// caller code
foo(7, "wombats");Then you can make a runnable implementation thus:public class Foo implements Runnable {
final int quantity_;
final String name_;
public Foo (int quantity, String name) {
quantity_ = quantity;
name_ = name;
public void run () {
for (int i=0; i<quantity_; i++) {
System.out.println(name_);
// caller code
new Thread(new Foo(7, "wombats")).start();
You could overload this method to take parameters in
your class that implements the Runnable interface,
and then call the base run() method.I don't get what you mean by this; Runnable is an interface so there is no base class run() method, and a run() overloaded with extra parameters method wouldn't get called by the thread.
Pete -
Multi threading under single file channel
Hi,
We have File-Proxy scenario .
We are using fCC sender channel and using
recordset sequence as varaibale
recordsets per message was 250.
When large size file like 2GB was processed, PI is taking 45-50 min to process the file and from proxy end its taking 8 hrs to process this file.
we are using one channel and 250 recordsets per message by chunking file and process to target. We are following EOIO for sequence for these chunk files.
with this approach in PI target system proxy is taking huge time to process.
experts suggested using multi threading and multiple channels are the ideal solution for this issue.
am expecting with multiple channels and multi threading will cause issue for receiver proxy because of more objects and current approach is fine.
Please suggest any other alternatives we can acheive in PI with respect to this issue?
Note: I checked blog for file chunk option under Adv parameters and I cant use that here as FCC and Mapping is there .
Rgds,
amanHi Aman,
We had file to proxy interface and the XML payload of the proxy was around 400mb...to reduce the time taken in PI in mapping step we reduced the XML payload of the proxy by cutting the XML tagnames.
for example an xml field <firstname>Anand</firstname> was converted to <f>Anand</f>
with this we were able to achieve about 40-50% reduction in XML payload the file and a good improvement in the time taken by PI mapping to process the file.
Hope it helps,
Thanks,
Anand -
Hi All,
Want to know how we can multi-thread a program for a particular PLSQL code in Oracle EBS for which the child thread doesn't consume any thread in the front-end even though it executes with user-specified threads?Hi;
Please review below notes which could gives you some idea:
How Does iPayment Use Multi Threading? [ID 983478.1]
http://orabiz.blogspot.com/2010/06/ebs-plsql-multithreading-example.html
Can I have multi-thread program in EBS
Regard
Helios -
Multi-thread application recompile object with make but runs with old value
Hi. I am working on a simulation in Java, and there is some behavior going on that I cannot understand. Granted, I'm a mechanical engineer, not a CS student (a fact that is probably made obvious by the code I'm posting below). The simulation comprises three parts: a controller, a robot, and a 3-d sensor. Here's the code for the "Simulation" application.
class Simulation {
void go() {
ThreeDSensor sensorRunner = new ThreeDSensor();
VSController controllerRunner = new VSController();
KukaKR15SL robotRunner = new KukaKR15SL();
Thread sensorThread = new Thread(sensorRunner);
Thread controllerThread = new Thread(controllerRunner);
Thread robotThread = new Thread(robotRunner);
sensorThread.start();
try {
Thread.sleep(1000); // Give sensorThread time to start in order to catch first triggers
} catch(InterruptedException ex) {
ex.printStackTrace();
controllerThread.start();
try {
Thread.sleep(1000); // Give controllerThread time to open the socket for communication with robotThread
} catch(InterruptedException ex) {
ex.printStackTrace();
robotThread.start();
public static void main(String[] args) {
Simulation sim = new Simulation();
sim.go();
}I guess the big reason I'm using multi-threading is that once this simulation is working I want to be able to just run VSController alone and have it interface with a robot controller and a PC performing image processing. So with multiple threads I'm sending TCP and UDP messages around just like the final system will.
I have made an object for my VSController that just stores values used by the simulation. That way I could have them all in one place instead of hunting through methods to change them. One example is "double noiseThreshold". Quickly, here is the code for "ControllerSettings.java".
class ControllerSettings {
final double cameraXOffset = 0; // If > 0 then the origin of the camera CS is not on the center line of the lens
final double cameraYOffset = 0; // If > 0 then the origin of the camera CS is not on the center line of the lens
final double cameraZOffset = 700; // The distance that must be kept between the camera and the target
// Error magnitude less than this is disregarded (in centimeters if roundingData else in millimeters)
final double noiseThreshold = 60;
final boolean estimatingEndPoints = false; // If the controller is using two images per cycle then true
final boolean roundingData = false;
final boolean using3DData = true; // How double[] sent from Matlab image processing is used
* If the robot controller uses the output of this controller to command
* motions in cartesian space then true. This is used in two places: 1) initial guess of Jacobian,
* and 2) "commandType" element sent to robot controller.
final boolean useRobotControllerModel = false;
final double thetaBumpValueForEstimationOfJacobian = .1; // Distance each joint is jogged in estimation process
final double bumpDistance = 50; // Distance robot moves each time (magnitude of translation in mm)
final double limitAngular = .5; // Max amout robot joint will be commanded to rotate (in degrees)
}And here is some pertinent code from "VSController.java".
class VSController implements Runnable{
ControllerSettings cSettings; // Stores all the preferences used by the controller
NGN controller; // This is the controller algorithm.
int dof; // The degrees of freedom of the robot being controlled
KukaSendData ksd; // This provides communication to the robot.
protected DatagramSocket socketForVisionSystem = null;
ImageFeaturesData ifd; // This parses and stores data from the image system.
double[] errorVector; // This is what's acted on by the algorithm
PrintWriter errorTrackerOut = null; // For analysis of error vector
public void run() {
VSController vsc = new VSController();
vsc.go();
public void go() {
initWriters();
cSettings = new ControllerSettings();
public boolean isNoise() {
boolean ret = false;
double magnitude = 0;
for (int i = 0; i < errorVector.length; i++) {
magnitude += errorVector[i] * errorVector;
magnitude = Math.sqrt(magnitude);
if (magnitude <= cSettings.noiseThreshold) {
System.out.println("VSController: magnitude (of errorVector) = " + magnitude +
", threshold = " + cSettings.noiseThreshold); // Debug
Now here's my issue: I change the value for "noiseThreshold" in "ControllerSettings.java" then run make from terminal (makefile code posted below) and rerun "Simulation". However, despite my changes to "ControllerSettings.java" the value for "noiseThreshold" is not changed, as evidenced by the output on the terminal screen:VSController: magnitude (of errorVector) = 6.085046125925263, threshold = 10.0 See, that value of 10.0 is what I used to have for noiseThreshold. I do not know why this value does not update even though I save the java file and execute make in between executions of Simulation. I would love it if someone could explain this problem to me.
Here's the contents of makefile.
JFLAGS = -cp ../Jama\-1\.0\.2.jar:../utils/:/usr/share/java/vecmath\-1\.5\.2.jar:.
JC = javac
.SUFFIXES: .java .class
.java.class:
$(JC) $(JFLAGS) $*.java
CLASSES = \
ControllerSettings.java \
ImageFeaturesData.java \
KukaKR15SL.java \
../utils/KukaSendData.java \
NGN.java \
Puma560.java \
Robot.java \
RobotSettings.java \
Simulation.java \
SimulationSettings.java \
SixRRobot.java \
Targets.java \
TargetsSettings.java \
ThreeDData.java \
ThreeDSensor.java \
VSController.java
default: classes
classes: $(CLASSES:.java=.class)
clean:
$(RM) *.classEdited by: raequin on Apr 5, 2010 1:43 PMI saw this explanation about what's causing my problem.
"When the Java compiler sees a reference to a final static primitive or String, it inserts the actual value of that constant into the class that uses it. If you then change the constant value in the defining class but don't recompile the using class, it will continue to use the old value."
I verified that the value updates if I also change something in VSController.java, forcing it to recompile. I think I will solve this problem by just making the variables in ControllerSettings no longer final (and then recompile VSController to make sure it takes effect!). Is there another solution? I saw intern(), but that seems to only apply to Strings.
Thanks. -
I desing a program to test the speed of using multi threads to add up from 0 to 1000000000
As I know from some books ,I assumed that the multithread to caculate should faster than single thread , but what supprised me is that I was wrong , the result is that : 5 threads is slower than single thread ,and so did 10 threads slower than 5 threads !
why ?"Adding up" a sequential series of numbers doesn't
sound like a good application for multithreading.How
did you divide up the responsibility among multiple
threads?You use a divide-and-conquer strategy. The sequence is
split into halves recursively down to a certain depth
(sequence length) and distributed among the avilable
processors.Thanks for the explanation, but I understand that - I assumed (perhaps incorrectly) that the OP is testing on a single-processor system (one reason why the threading didn't improve performance as expected) or that the actual code to accomplish the multithreading was improperly implemented (another reason). That's why I asked what the OP did to divide up the responsibility. :o) -
Java multi-thread Applet and Multi-processor
Hello,
I have a JAVA applet which work fine on a mono-processeur machine and not fine at all on multi-processors.
It use multi thread (for reading on socket) and some times, request are lost.
Is that a matter of programming or a JVM bug ?
This happens on Linux and Windows NT bi-processors.
We hare using JAVA 1.3.0_02
Thanks for your help
[email protected]I have already have a look to javax.swing.SwingUtilities.invokeLater() but (I think) it don't work for my need.
A graphic applet which create 2 threads : one for reading and one for writing on a socket.
Request sent to the server are memorized in a vector, and once answer is received, the request is remove from vector and treated. Access to the list is protected by synchronize.
Everything works fine one several plateforme (linux, windows 98/2000/NT, Solaris). The only problem is on multi-processor : request are lost ! -
Can Acrobat 9 Multi-Thread (use all my cpu cores)
i have several 700+ page thick PDF documents i want to run OCR on. i can batch run them just fine, however i cannot get adobe to use more than one core of my 8 core iMac. so the process takes needlessly long because 87% of my CPU power is just sitting idle. i also cannot do anything with adobe while it is running its OCR program.
is there a way to force acrobat to be multi-threaded?
is there a way to use it for other things while its working?Nope, no version of Acrobat is a multithreaded application. See the first bullet point: http://livedocs.adobe.com/acrobat_sdk/9.1/Acrobat9_1_HTMLHelp/DevFAQ_Introduction.21.16.ht ml
-
Multi-Threaded server using ThreadPool
Dear friends,
I am writing a client-server program in which the client and server communicate using SUN-RPC. The client reads a file containing some numbers and then spawns threads which it uses to request the server for a service. These threads are executed using a thread pool. Till this time, it's working fine. But when it comes to the server, the real trouble begins because it too needs to be made a multi-threaded one using thread pooling. The server has to capture the call information for each request for the service and then pass this information to a thread/runnable object in whose run() method the code for execution of the service would be present. Since the tasks(requests for the service) are not present already, i am unable to execute the server side threads in a loop using a thread pool. How to solve this problem? Kindly help.
Thanks,
SubhashThe server has to capture the call information for each request for the serviceWhy?
and then pass this information to a thread/runnable object in whose run() method the code for execution of the service would be present.Why can't the run() method get the call information when it starts? That's what's normally done. The server's accept loop mustn't do any other I/O: otherwise a rogue client can block the server complete.y -
Multi-threaded performance server using 2 ports to two-way communication
Hi, I'm new in the forums so welcome everyone. I'm developing now an online computer game based on orginal Polish board-game, but it doesn't mean. Important is that I need to develope a high-performance multi-threaded server, which can serve... let's say few hundres of games, and a thousend of players simulateously. My server works on two ports/sockets.
First one is represented by "ServerSocketChannel clientConSsc" in my code. The main thread in my server class which invokes the method "run()" (which You can see below), registers clientConSsc with Selector and then repeatingly accepts incoming connections from clients on this socket. When connection(channel) is estabilished and clients wants to write some request to this channel, the main thread on server creates a new instance of class "RequestHandler" which extends Thread and handles this request (reads the request from channel, makes some changes on server, spreads some new messages to other clients in the same game and so on... everything on the same socket/port/channel). Then the channel/connection is closed by the server - I call such connections: "a short connections". In the same time the main thread continues the loop and is still able to accept connections from another players. That's the idea of multi-threaded server, right? :) And to this point, everything works fine, but... what if the server wants to trigger some new command, write new information to client?
Server could have tried to open a SocketChannel to client's IP address, but then the client programme would have to create and ServerSocketChannel object, bind it to some InetAddress and then... and then client becomes a server! - that breaks the idea of client-server cooperation and demands on players of my game to have routed some port on their machines. To resolve this problem I made some sort of "system" which, when some player/client is logging into my server, accepts second (this time constant, not "short") connection on the second port I mentoined on the beginning. This connection is held in variable "SocketChannel serverCon" of class "Player" - which reflects a player logged onto server. Server maintains every such connection till the client logs off. After the connection is accepted, the player whom connection it was is added to collection called "playersToRegisterToWrite". After the Selector.selectNow() is invoked (as You can see in the code below), each and every player's connection is registered in selector (with selection key - OP_WRITE and attachment pointing on owning player). In the same time client's code is trying to read some bytes from this connection and blocks on it until some bytes are written to this connection. When server wants to "tell" something to client, deliver some message/command, it creates a new instance of class which extends an abstract class called "ServerAction" (another new thread) and adds it to collection "actionsToDo". In ServerAction's method "run()" there are whole code to interact with client (e.g. send an update of players' list, an update of games' list, a chat message). Finnaly when Selector informs the server that some connection is writable (some client is waiting for commands), then server checks if there's any "actionToDo" involving this client/player. If there is, it unregisters the connection from Selector (so no other ServerAction (thread) can write on this connection) and starts the action. At the end of every "run()" method of subclass of ServerAction there's a code, which again adds the player to collection "playersToRegisterToWrite", so the player's connection can again be registered in Selector and the player can again receive informations from server - after it consumed THIS "ServerAction".
It looks to me like it should be working fine, but it's not. When I test my server and clients on the same machine (no ping/latency) everything seems to be working fine. But when it comes to play my game with somebody even on LAN or through the Internet there comes the problems. My first socket I describe (and first type of connections - short connections) works perfectly fine, so the requests triggered by client are delivered and handled properly. But the second socket is cirppling. For example: the server triggers a command refering to an update of clients logged to server' list. It is triggered by Selector so the client should be ready to read data from server, so the server sends data! And the client never receives it... Why?
It experimented a whole lot of time on SocketChannel's method "configureBlocking(boolean)", but it never helps. I think the client should always block it's listening thread on connection, contratry to server which is ment to be fast, so it should send the data through non-blocking channels. Am I right? Are there any rules refering blocking configuration of SocketChannels?
I will be grateful for every answer. To help You out I attach also drafts from run()'s methods of my classes.
Server's main method - main thread :
public void run() {
try {
selector = Selector.open();
clientConSsc.configureBlocking(false);
clientConSsc.register(selector , SelectionKey.OP_ACCEPT);
while(serverRunning) {
try {
selector.selectNow();
Iterator it;
synchronized(playersToRegisterToWrite) {
it = playersToRegisterToWrite.iterator();
while(it.hasNext()) {
Player player = (Player)it.next();
it.remove();
player.serverCon.configureBlocking(false);
player.serverCon.register(selector , SelectionKey.OP_WRITE , player);
Set keys = selector.selectedKeys() {
it = keys.iterator();
while(it.hasNext()) {
SelectionKey key = (SelectionKey)it.next();
if(key.isAcceptable()) {
it.remove();
clientCon = clientConSsc.accept();
clientCon.configureBlocking(false);
clientCon.register(selector , SelectionKey.OP_READ);
continue;
if(key.isReadable()) {
it.remove();
key.cancel();
new RequestHandler(this , (SocketChannel)key.channel()).start();
continue;
if(key.isWritable()) {
if(key.attachment() != null ) {
ServerAction action = null;
synchronized(actionsToDo) {
Iterator aIt = actionsToDo.iterator();
while(aIt.hasNext()) {
ServerAction temp = (ServerAction)aIt.next();
if(temp.getPlayer().equals((Player)key.attachment())) {
action = temp;
aIt.remove();
break;
if(action != null) {
key.channel().configureBlocking(false);
it.remove();
key.cancel();
action.start();
continue;
} catch(Exception e) {
statusArea.append(e.toString() + "\n");
e.printStackTrace();
continue;
} catch(ClosedChannelException e) {
statusArea.append(e.toString() + "\n");
} catch(IOException e) {
statusArea.append(e.toString() + "\n");
A part of server's RequestHandler's class' method run() - the method which handles requests triggered by client on first port:
public void run() {
boolean served = false;
try {
channel.configureBlocking(true);
retryCount++;
retry = false;
String command = ns.readText(channel).trim();
ns.statusArea.append("ktos przesyla komende: " + command + "\n");
if(command != null && !command.equals("ERROR")) {
String[] cmd = command.split("�");
ns.statusArea.append("komenda: " + cmd[0] + "\n");
if(cmd[0].equals("CHAT")) {
if(cmd.length != 5) {
retry();
} else {
if(cmd[2].equals("NOGAME")) { // jezeli nie ma okreslonej gry czyli rozsylamy do wszystkich
for(int i = 0 ; i < ns.loggedPlayersListItems.size() ; i++) {
Player current = (Player)ns.loggedPlayersListItems.get(i);
if(current.state == Player.CHOOSING && !current.equals(new Player(Integer.parseInt(cmd[1])))) // jezeli gracz jest w okienku wybierania gry to wysylamy mu broadcast
ns.actionsToDo.add(new SendMsg(ns , current , "CHAT�" + cmd[1] + "�" + cmd[3] + "�" + cmd[4]));
} else {
Game game = (Game)ns.gamesListItems.get(ns.gamesListItems.indexOf(new Game(Integer.parseInt(cmd[2]))));
for(int i = 0 ; i < game.players.size() ; i++) {
Player current = (Player)game.players.get(i);
if(!current.equals(new Player(Integer.parseInt(cmd[1]))))
ns.actionsToDo.add(new SendMsg(ns , current , "CHAT�" + cmd[1] + "�" + cmd[3] + "�" + cmd[4]));
served = true;
} else if(cmd[0].equals("GETGAMEINFO")) {
if(cmd.length != 3)
retry();
else {
int gameID = Integer.parseInt(cmd[2]);
ns.statusArea.append("poproszono o informacje o grze nr: " + gameID + "\n");
Game checkedGame = new Game(gameID);
if(ns.gamesListItems.contains(checkedGame)) {
Game game = (Game)ns.gamesListItems.get(ns.gamesListItems.indexOf(checkedGame));
channel.configureBlocking(true);
ObjectOutputStream oos = new ObjectOutputStream(channel.socket().getOutputStream());
oos.writeObject(game);
oos.writeObject(game.players);
oos.flush();
ns.statusArea.append("wyslano informacje o grze nr: " + gameID + "\n");
} else {
ns.statusArea.append("brak gry o nr: " + gameID + "\n");
served = true;
} catch(IOException e) {
e.printStackTrace();
if(!served) {
ns.findAndDisconnectPlayer(channel);
try {
channel.close();
} catch(IOException e) {
e.printStackTrace();
}An example of ServerAction's subclass - the class which triggers server commands to client on second port:
class UpdateLoggedPlayersList extends ServerAction {
public UpdateLoggedPlayersList(NeuroServer ns , Player player) {
super(ns , player);
public void run() {
try {
serverCon.configureBlocking(true);
ns.sendText("UPDATELOGGEDPLAYERSLIST" , serverCon);
if(ns.readText(serverCon).equals("OK")) {
ObjectOutputStream oos = new ObjectOutputStream(serverCon.socket().getOutputStream());
oos.writeObject(ns.loggedPlayersListItems);
oos.flush();
synchronized(ns.playersToRegisterToWrite) {
ns.playersToRegisterToWrite.add(player);
} catch(IOException e) {
e.printStackTrace();
}A part of client's CmdHandler's class' method run() - the method which handles commands triggered by server:
public void run() {
try {
while(works) {
String command = nc.readText(nc.serverCon);
System.out.println("Server przesyla komende: " + command + "\n");
String[] cmd = command.split("�");
if(cmd[0] != null && !cmd[0].equals("ERROR")) {
if(cmd[0].equals("CHAT")) {
if(nc.chooseGameDialog != null && nc.chooseGameDialog.isVisible()) { // jezeli na wybieraniu gry
newChatEntry(cmd[2] , null , cmd[3] , nc.chooseGameDialog.chatPane);
} else if(nc.readyDialog != null && nc.readyDialog.isVisible()) { // jesli na przygotowywaniu
Player sender = (Player)nc.actGame.players.get(nc.actGame.players.indexOf(new Player(Integer.parseInt(cmd[1]))));
newChatEntry(cmd[2] , sender.fraction , cmd[3] , nc.readyDialog.chatPane);
} else if(nc.ng != null) { // jesli w grze
Player sender = (Player)nc.actGame.players.get(nc.actGame.players.indexOf(new Player(Integer.parseInt(cmd[1]))));
newChatEntry(cmd[2] , sender.fraction , cmd[3] , nc.ng.inGameChatPane);
} else if(cmd[0].equals("UPDATELOGGEDPLAYERSLIST")) {
nc.sendText("OK" , nc.serverCon , false);
nc.serverCon.configureBlocking(true);
ObjectInputStream ois = new ObjectInputStream(nc.serverCon.socket().getInputStream());
DefaultListModel players = (DefaultListModel)ois.readObject();
nc.chooseGameDialog.updateLoggedPlayersList(players);
} catch(IndexOutOfBoundsException e) {
System.out.println(e);
} catch(IOException e) {
System.out.println(e);
} catch(ClassNotFoundException e) {
System.out.println(e);
}And two methods I used in codes above: sendText(String text , SocketChannel sc) and readText(SocketChannel sc) - they are my "utility" methods, which I use to send and receive Strings through specified SocketChannels.
boolean sendText(String text , SocketChannel sc) {
ByteBuffer bbuf = ByteBuffer.allocate(BSIZE);
boolean sendRetry;
boolean sent = false;
do {
sendRetry = false;
try {
StringBuffer cmd = new StringBuffer();
cmd.setLength(0);
if(text.length()+4 < 100)
cmd.append("0");
if(text.length()+4 < 10)
cmd.append("0");
cmd.append(Integer.toString(text.length()+4) + "�");
cmd.append(text);
cmd.append("\n");
bbuf = charset.encode(CharBuffer.wrap(cmd));
sc.write(bbuf);
bbuf.clear();
int n = sc.read(bbuf);
if(n == 1) {
bbuf.flip();
Byte re = bbuf.get();
if(re == 1) {
sendRetry = true;
} else {
sent = true;
} catch(Exception e) {
findAndDisconnectPlayer(sc);
try {
sc.close();
} catch(IOException f) {
f.printStackTrace();
return false;
} while(!sent && sendRetry);
return true;
String readText(SocketChannel sc) {
ByteBuffer bbuf = ByteBuffer.allocate(BSIZE);
int readRetryCount = -1;
boolean readRetry;
do {
readRetry = false;
readRetryCount++;
StringBuffer cmd = new StringBuffer();
cmd.setLength(0);
bbuf.clear();
try {
readLoop:
while(true) {
int n = sc.read(bbuf);
if(n > 0) {
bbuf.flip();
CharBuffer cbuf = charset.decode(bbuf);
while(cbuf.hasRemaining()) {
char c = cbuf.get();
if(c == '\r' || c == '\n') break readLoop;
cmd.append(c);
} else break;
statusArea.append(Thread.currentThread().getId() + " readText() odczytuje: " + cmd.toString() + "\n");
if(cmd.length() < 3 || Integer.parseInt(cmd.substring(0 , 3)) != cmd.length()) {
sc.write(ByteBuffer.wrap(new byte[] {1}));
readRetry = true;
} else {
sc.write(ByteBuffer.wrap(new byte[] {0})); // length OK
return cmd.toString().substring(4 , cmd.toString().length());
} catch(Exception e) {
findAndDisconnectPlayer(sc);
try {
sc.close();
} catch(IOException f) {
f.printStackTrace();
return "ERROR";
} while(readRetry && readRetryCount < 3);
findAndDisconnectPlayer(sc);
try {
sc.close();
} catch(IOException e) {
e.printStackTrace();
return "ERROR";
}Edited by: Kakalec on Jul 23, 2008 11:04 AMYou seem to be using a horrendous mixture of PrintWriters, BufferedReaders, ObjectOutputStreams, and no doubt ObjectInputStreams. You can't do that.
Some rules about this:
(a) Whenever you use a stream or reader or writer on a socket, you must allocate it once for the life of the socket, not every time you want to do an I/O.
There are many reasons for this including losing buffered data in the old stream and auto-closure of the socket on garbage-collection of the old stream.
(b) You can't mix stream types on the same socket. (i) If you're writing objects, use an ObjectOutputStream, you must read with an ObjectInputStream, and you can't read or write anything that isn't supported by the API of ObjectOutputStream. (ii) If you're writing lines, use a BufferedWriter and a BufferedReader at the other end. If you're writing characters, use a Writer and a Reader. (iii) If you're writing primitive data or UTF strings, use a DataOutputStream and a DataInputStream. (iv) If you're writing bytes, use DataOutputStream and a DataInputStream or an OutputStream and an InputStream. You can't mix (i), (ii), (iii), and (iv).
(c) Don't use PrintWriter or PrintStream over the network. They swallow exceptions that you need to know about. They are for writing to the console, or log files, where you don't really care about exceptions.
(d) Call flush() before reading.
(e) Always close the 'outermost' output stream or writer of a socket, never the input stream or the socket itself. Closing any of these closes the socket and therefore makes the other stream unusable, but only closing the output stream/writer will flush it.
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