Good night guys!
I'm having the following problem ...
I have a web application that runs a "thread" that takes messages from the queue (MSMQ) ... Everything works correctly .. the problem is when I get this message, I can not display .. because the method that returns the message content is a "static" ..
I need to perform a function in JS to display this message.
conclusion:
The method "ProcessMessage" can not be named because he is not a static method ...
My main goal is to call a function in JS passing as parameter (m.Body.ToString ()) which is the content of the message.
Can anyone help me?
Thank you for sharing your knowledge!
This is my code.
public void StartThread()
{
try
{
while (true)
{
PrepareQueue();
}
}
catch (Exception)
{ }
}
public static void PrepareQueue()
{
MessageQueue myQueue = new MessageQueue(".\\private$\\CTIQueue");
myQueue.Formatter = new XmlMessageFormatter(new Type[] { typeof(String) });
// Add an event handler for the ReceiveCompleted event.
myQueue.ReceiveCompleted += new ReceiveCompletedEventHandler(MyReceiveCompleted);
// Define wait handles for multiple operations.
WaitHandle[] waitHandleArray = new WaitHandle[10];
for (int i = 0; i < 10; i++)
{
// Begin asynchronous operations.
waitHandleArray[i] = myQueue.BeginReceive().AsyncWaitHandle;
}
// Specify to wait for all operations to return.
WaitHandle.WaitAll(waitHandleArray);
return;
}
private static void MyReceiveCompleted(Object source, ReceiveCompletedEventArgs asyncResult)
{
try
{
Thread.Sleep(2000);
MessageQueue mq = (MessageQueue)source;
// End the asynchronous receive operation.
System.Messaging.Message m = mq.EndReceive(asyncResult.AsyncResult);
ProcessMessage(m.Body.ToString()); <-- MY PROBLEM
}
catch (MessageQueueException)
{ }
return;
}
public void ProcessMessage(string message)
{
ScriptManager.RegisterStartupScript(this, GetType(), "popup", "NewCaller('" + message + "');", true);
}
Why not instantiate an object of the class and call ProcessMessage on it? Static methods can instantiate an object of the enclosing class and invoke instance methods on it.
private static void MyReceiveCompleted(Object source, ReceiveCompletedEventArgs asyncResult)
{
try
{
Thread.Sleep(2000);
MessageQueue mq = (MessageQueue)source;
// End the asynchronous receive operation.
System.Messaging.Message m = mq.EndReceive(asyncResult.AsyncResult);
new MyClass().ProcessMessage(m.Body.ToString()); <-- MY PROBLEM
}
catch (MessageQueueException)
{ }
return;
}
But if you are planning to invoke a client side code from server side, with reactive action happening at the server's end(which I think is your case) -- then I would prefer you use ASP.NET SignalR to signal the client that something interesting has happened at the server's end.
Related
I wrote a little code to download some files from internet..if user click on cancel button this must be stopped..i use the cancel() method for do it..but it didn't work.
ScheduledService<Object> service = new ScheduledService<Object>() {
protected Task<Object> createTask() {
return new Task<Object>() {
protected Object call() {
if (checkinternet()) {
downloadFiles();
}
return null;
}
};
}
};
service.start();
In buttons action event handler i called cancel method for stop service..
but it wasn't successful..
service.cancel();
How do i do that...
There is no automatic way to cancel a task or service.
From the documentation (https://docs.oracle.com/javase/8/javafx/interoperability-tutorial/concurrency.htm):
Cancelling the Task.
There is no reliable way in Java to stop a thread in process. However, the task must stop processing whenever cancel is called on the task. The task is supposed to check periodically during its work whether it was cancelled by using the isCancelled method within the body of the call method.
The example referenced in the above block looks like this:
Task<Integer> task = new Task<Integer>() {
#Override protected Integer call() throws Exception {
int iterations;
for (iterations = 0; iterations < 100000; iterations++) {
if (isCancelled()) {
break;
}
System.out.println("Iteration " + iterations);
}
return iterations;
}
};
So you will have to implement the cancel logic by yourself, unfortunately.
I've created a custom activity which contains as a Body another Activity.
[Browsable(false)]
public Activity Body { get; set; }
protected override void Execute(NativeActivityContext context)
{
ActivityInstance res = context.ScheduleActivity(Body, new CompletionCallback(OnExecuteComplete), OnFaulted);
}
private void OnFaulted(NativeActivityFaultContext faultContext, Exception propagatedException, ActivityInstance propagatedFrom)
{
throw new Exception(propagatedException.Message);
}
When an exception is thrown during the execution of the Body, ma handler for the OnFaulted is hit.
My execution starts with a call to static method Run of the WorkflowApplication class. My WorkflowApplication instance has a handler associated for the OnUnhandledException event.
instance.OnUnhandledException +=
delegate(WorkflowApplicationUnhandledExceptionEventArgs args)
{
Console.WriteLine(args.ExceptionSource);
waitEvent.Set();
return UnhandledExceptionAction.Cancel;
};
But regardless of what happens when the Activity hosted in the Body is executed, i never reach the handler defined above. I thought that if i throw an exception from the OnFaulted, i will be able to redirect the flow to the OnUnhandledException but i was wrong. Any ideas ?
I need this in order to centralize my errors, check them and display messages accordingly. Also i need a way to stop the execution and so on and i don't want to define handlers all over the application. Is there any way to accomplish this ?
As Will suggested, i will post what i did to handle my scenario.
Basically, in my custom activity i have hosted an Assign :
[Browsable(false)]
public Activity Body { get; set; }
Activity System.Activities.Presentation.IActivityTemplateFactory.Create(System.Windows.DependencyObject target)
{
return new Assignment()
{
Body = new Assign() { DisplayName = "" }
};
}
I've added this code to my Execute method :
ActivityInstance res = context.ScheduleActivity(Body, new CompletionCallback(OnExecuteComplete), OnFaulted);
I was trying to run this Assignment by giving an array a negative value as index and and an exception was thrown. This, somehow ended my execution but no handler for the events of my WorkflowApplication instance were hit.
Here is the method given as a callback when executing the body ( in our case the Assign activity ) :
private void OnFaulted(NativeActivityFaultContext faultContext, Exception propagatedException, ActivityInstance propagatedFrom)
{
faultContext.HandleFault();
CommunicationExtension ce = faultContext.GetExtension<CommunicationExtension>();
ITextExpression toTextExpression = (propagatedFrom.Activity as Assign).To.Expression as ITextExpression;
string valueTextExpression = string.Empty;
if ((propagatedFrom.Activity as Assign).Value != null)
{
if ((propagatedFrom.Activity as Assign).Value.Expression != null)
valueTextExpression = (propagatedFrom.Activity as Assign).Value.Expression.ToString();
}
if (ce != null)
{
ce.AddData(string.Format("{0} found on Assignment definition [{1} = {2}]", propagatedException.Message, toTextExpression.ExpressionText, valueTextExpression));
}
}
The trick was to call :
faultContext.HandleFault();
and use CommunicationExtension to allow me to to display the erros in the GUI.
The code for this class is trivial :
public class CommunicationExtension
{
public List<string> Messages { get; set; }
public CommunicationExtension()
{
Messages = new List<string>();
}
public void AddData(string message)
{
if (string.IsNullOrEmpty(message))
return;
Messages.Add(message);
}
}
Use this to add the extension:
CommunicationExtension ce = new CommunicationExtension();
instance.Extensions.Add(ce);
where instance is my WorkflowApplication instance.
I understood that for each instance of the workflow application we have one instance of its extension class. So i can send messages like this from all my custom activities in order to display their status.
I hope this scenario can help other people too.
I am new to networking, and I am trying to network a board game that I have created using java.A friend of mine pointed me towards the Kryonet library. So far, it's great. I don't have to deal with sockets!
The problem I'm coming across is sending objects. Mainly, I have a Board type object. This object contains other objects, such as ArrayList objects and Fort objects.
I tried just registering the Board object, but I received these errors:
Exception in thread "Server" com.esotericsoftware.kryo.KryoException: java.lang.
IllegalArgumentException: Class is not registered: Game.Tile
Note: To register this class use: kryo.register(Game.Tile.class);
Serialization trace:
t0 (Game.Board)
at com.esotericsoftware.kryo.serializers.FieldSerializer$ObjectField.write(FieldSerializer.java:585)
at com.esotericsoftware.kryo.serializers.FieldSerializer.write(FieldSerializer.java:213)
at com.esotericsoftware.kryo.Kryo.writeClassAndObject(Kryo.java:571)
at com.esotericsoftware.kryonet.KryoSerialization.write(KryoSerializatio
n.java:50)
at com.esotericsoftware.kryonet.TcpConnection.send(TcpConnection.java:192)
etc....
Ok fine, Then I will also register Tile.class,
More errors, but then I need to register ArrayList.class - so I register it, and again more errors, so I register Fort.class.
When I register Fort.class, I enter into an infinite loop and get a ton of errors like this:
at com.esotericsoftware.kryo.serializers.FieldSerializer$ObjectField.write(FieldSerializer.java:564)
at com.esotericsoftware.kryo.serializers.FieldSerializer.write(FieldSerializer.java:213)
at com.esotericsoftware.kryo.Kryo.writeObject(Kryo.java:504)
at com.esotericsoftware.kryo.serializers.FieldSerializer$ObjectField.write(FieldSerializer.java:564)
at com.esotericsoftware.kryo.serializers.FieldSerializer.write(FieldSerializer.java:213)
at com.esotericsoftware.kryo.Kryo.writeObject(Kryo.java:504)
at com.esotericsoftware.kryo.serializers.FieldSerializer$ObjectField.write(FieldSerializer.java:564)
This leads me to believe I don't quite understand how to register properly and I can't find much information about how to register nested objects. My Fort class is actually an enumerated class but I'm not sure if that makes a difference? Any help would be greatly appreciated!
I have included a class with most of my networking code so you can see an idea of what I am trying to do.
This is my code for the networking:
public class Network extends Listener {
private Server server;
private Client client;
private boolean isServer;
private boolean messageReceived;
private PacketMessage message;
private Board board;
public Network(boolean isServer, Board board) throws IOException {
messageReceived = false;
this.board = board;
this.isServer = isServer;
if (isServer) {
initServer();
// receive();
} else {
initClient();
//probably want to run this in main
client();
}
}
private void initServer() throws IOException {
// 127.0.0.1 means myself
// ports up to 1024 are special and reserved
server = new Server();
registerClasses(server.getKryo());
server.bind(8000, 8001);
// starting a new thread
server.start();
// call my received and my connected
server.addListener(this);
}
private void initClient() throws IOException {
// 127.0.0.1 means myself
// ports up to 1024 are special and reserved
client = new Client();
registerClasses(client.getKryo());
// starting a new thread
client.start();
client.connect(5000, "127.0.0.1", 8000, 8001);
// call my received and call my connected
client.addListener(this);
}
//call in main
//
public void client(){
while(true){
sendRequest();
receive();
try {
Thread.sleep(5000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
// tell Kryo what things it's going to have to send
private void registerClasses(Kryo kryo) {
kryo.register(Request.class);
kryo.register(PacketMessage.class);
kryo.register(Fort.class);
kryo.register(ArrayList.class);
kryo.register(Tile.class);
kryo.register(Board.class);
}
private void sendRequest() {
client.sendTCP(new Request());
}
private void receive() {
messageReceived = false;
while (!messageReceived) {
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
// message.message is really packet.message
System.out.println("Received a message from the host: "
+ message.message);
}
public void received(Connection c, Object p) {
System.out.println("Received Message");
// Is the received packet the same class as PacketMessage.class?
if (p instanceof PacketMessage) {
// Cast it so we can access the message within
// PacketMessage packet =(PacketMessage) p;
// System.out.println("Received a message from the host: "+pa cket.message);
message = (PacketMessage) p;
// We have now received the message!
messageReceived = true;
}
else if (p instanceof Request){
// Create a message packet
PacketMessage packetMessage = new PacketMessage();
// Assign the message text
packetMessage.message = "Hello friend! The time is: "
+ new Date().toString();
// Send the message
//probably want another method to send
c.sendTCP(packetMessage);
c.sendTCP(board);
}
}
// This is run when a connection is received!
public void connected(Connection c) {
System.out.println("Received a connection from "
+ c.getRemoteAddressTCP().getHostString());
}
}
What is likely happening is that your Fort class contains a member of type Board, and this circular reference causes an infinite loop when serializing Fort.
Use the transient keyword to exclude members from serialization, or remove the circular reference altogether.
I'm making a small game in LibGDX. I'm saving the player's username locally as well as on a server. The problem is that the application is not waiting for the result of the call so the online database's ID is not saved locally. Here's the overall flow of the code:
//Create a new user object
User user = new User(name);
//Store the user in the online database
NetworkService networkService = new NetworkService();
String id = networkService.saveUser(user);
//Set the newly generated dbase ID on the local object
user.setId(id);
//Store the user locally
game.getUserService().persist(user);
in this code, the id variable is not getting set because the saveUser function is returning immediately. How can I make the application wait for the result of the network request so I can work with results from the server communication?
This is the code for saveUser:
public String saveUser(User user) {
Map<String, String> parameters = new HashMap<String, String>();
parameters.put("action", "save_user");
parameters.put("json", user.toJSON());
HttpRequest httpGet = new HttpRequest(HttpMethods.POST);
httpGet.setUrl("http://localhost:8080/provisioner");
httpGet.setContent(HttpParametersUtils.convertHttpParameters(parameters));
WerewolfsResponseListener responseListener = new WerewolfsResponseListener();
Gdx.net.sendHttpRequest (httpGet, responseListener);
return responseListener.getLastResponse();
}
This is the WerewolfsResponseListener class:
class WerewolfsResponseListener implements HttpResponseListener {
private String lastResponse = "";
public void handleHttpResponse(HttpResponse httpResponse) {
System.out.println(httpResponse.getResultAsString());
this.lastResponse = httpResponse.getResultAsString();
}
public void failed(Throwable t) {
System.out.println("Saving user failed: "+t.getMessage());
this.lastResponse = null;
}
public String getLastResponse() {
return lastResponse;
}
}
The asynchrony you are seeing is from Gdx.net.sendHttpRequest. The methods on the second parameter (your WerewolfsResponseListener) will be invoked whenever the request comes back. The success/failure methods will not be invoked "inline".
There are two basic approaches for dealing with callbacks structured like this: "polling" or "events".
With polling, your main game loop could "check" the responseListener to see if its succeeded or failed. (You would need to modify your current listener a bit to disambiguate the success case and the empty string.) Once you see a valid response, you can then do the user.setId() and such.
With "events" then you can just put the user.setId() call inside the responseListener callback, so it will be executed whenever the network responds. This is a bit more of a natural fit to the Libgdx net API. (It does mean your response listener will need a reference to the user object.)
It is not possible to "wait" inline for the network call to return. The Libgdx network API (correctly) assumes you do not want to block indefinitely in your render thread, so its not structured for that (the listener will be queued up as a Runnable, so the earliest it can run is on the next render call).
I would not recommend this to any human being, but if you need to test something in a quick and dirty fashion and absolutely must block, this will work. There's no timeout, so again, be prepared for absolute filth:
long wait = 10;
while(!listener.isDone())
{
Gdx.app.log("Net", "Waiting for response");
try
{
Thread.sleep(wait *= 2);
}
catch (InterruptedException e)
{
e.printStackTrace();
}
}
public static class BlockingResponseListener implements HttpResponseListener
{
private String data;
private boolean done = false;
private boolean succeeded = false;
#Override
public void handleHttpResponse(HttpResponse httpResponse)
{
Gdx.app.log("Net", "response code was "+httpResponse.getStatus().getStatusCode());
data = httpResponse.getResultAsString();
succeeded = true;
done = true;
}
#Override
public void failed(Throwable t)
{
done = true;
succeeded = false;
Gdx.app.log("Net", "Failed due to exception ["+t.getMessage()+"]");
}
public boolean succeeded()
{
return succeeded;
}
public boolean isDone()
{
return done;
}
public String getData()
{
return data;
}
}
I am going to be using Session["firmaid"] quite alot in my application. This value is set when someone logs in to my system.
If something happens, and this value is lost from the Session, i would like to somehow have a global method that will get it, if it throws a NullReferenceException.
How can i do this?
Currently, my solution is to try and catch every time i use Session["firmaid"], then execute the method that will put firmaid in the Session, if it throws an Exception.
Is there an easier way to do this?
Instead of try/catching everytime you could wrap the access to the session in a strongly typed class and then access the session through this wrapper.
Or even write an extension method:
public static class SessionExtensions
{
public static string GetFirmaId(this HttpSessionStateBase session)
{
var firmaid = session["firmaid"] as string;
if (string.IsNullOrEmpty(firmaid))
{
// TODO: call some method, take respective actions
}
return firmaid;
}
}
and then in your code instead of:
try
{
var firmaid = Session["firmaid"];
// TODO: do something with the result
}
catch (Exception ex)
{
// TODO: call some method, take respective actions
}
use:
var firmaid = Session.GetFirmaId();
// TODO: do something with the result
Why not simply write a static wrapper around this? Much more robust and more DRY:
public static int GetFirmaid() {
if (HttpContext.Current.Session["firmaid"] == null) {
//do something to fall back
}
return HttpContext.Current.Session["firmaid"]
}
You obviously would have to put this in a Class you can easily access and then call it through:
Class.GetFirmaid()
You can create an action filter which will ensure that Session["firmaid"] has a value:
public class SetFirmaIdAttribute : ActionFilterAttribute
{
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
try
{
var firmaId = Session["firmaid"];
}
catch (Exception ex)
{
// pass filterContext if you need access to Request, Session etc.
Session["firmaid"] = SetFirmaId(filterContext);
}
}
private int SetFirmaId(ActionExecutingContext filterContext)
{
// TODO: implement some logic
}
}
OnActionExecuting will be called before action executes so you will already have Session["firmaid"] set when the action gets executed.
Once you implement this attribute you can put it on an action, controller or set it as global.