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  • Perl TCP Server handling multiple Client connections

    - by Matt
    I'll preface this by saying I have minimal experience with both Perl and Socket programming, so I appreciate any help I can get. I have a TCP Server which needs to handle multiple Client connections simultaneously and be able to receive data from any one of the Clients at any time and also be able to send data back to the Clients based on information it's received. For example, Client1 and Client2 connect to my Server. Client2 sends "Ready", the server interprets that and sends "Go" to Client1. The following is what I have written so far: my $sock = new IO::Socket::INET { LocalHost => $host, // defined earlier in code LocalPort => $port, // defined earlier in code Proto => 'tcp', Listen => SOMAXCONN, Reuse => 1, }; die "Could not create socket $!\n" unless $sock; while ( my ($new_sock,$c_addr) = $sock->accept() ) { my ($client_port, $c_ip) = sockaddr_in($c_addr); my $client_ipnum = inet_ntoa($c_ip); my $client_host = ""; my @threads; print "got a connection from $client_host", "[$client_ipnum]\n"; my $command; my $data; while ($data = <$new_sock>) { push @threads, async \&Execute, $data; } } sub Execute { my ($command) = @_; // if($command) = "test" { // send "go" to socket1 print "Executing command: $command\n"; system($command); } I know both of my while loops will be blocking and I need a way to implement my accept command as a thread, but I'm not sure the proper way of writing it.

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  • ThreadExceptionEventHandler and invoking delegates

    - by QmunkE
    If I assign a ThreadExceptionEventHandler to Application.ThreadException, why when I invoke a delegate method using a control on the main application thread are any exceptions thrown by that delegate not triggering the event handler? i.e. static void Main() { ... Application.ThreadException += new System.Threading.ThreadExceptionEventHandler(Application_ThreadException); Application.Run(new Form1()); } static void Application_ThreadException(object sender, System.Threading.ThreadExceptionEventArgs e) { Console.Error.Write("A thread exception occurred!"); } ... private void Form1_Load(object sender, EventArgs e) { Thread syncThread = new Thread(new ThreadStart(this.ThrowException)); syncThread.Start(); } private void ThrowException() { button1.Invoke(new MethodInvoker(delegate { // Not handled by ThreadExceptionEventHandler? throw new Exception(); })); } The context on this is that I have a background thread started from a form which is throwing an unhandled exception which terminates the application. I know this thread is going to be unreliable since it is network connectivity reliant and so subject to being terminated at any point, but I'm just interested as to why this scenario doesn't play out as I expect?

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  • Handling very large lists of objects without paging?

    - by user246114
    Hi, I have a class which can contain many small elements in a list. Looks like: public class Farm { private ArrayList<Horse> mHorses; } just wondering what will happen if the mHorses array grew to something crazy like 15,000 elements. I'm assuming that trying to write and read this from the datastore would be crazy, because I'd get killed on the serialization process. It's important that I can get the entire array in one shot without paging, and each Horse element may only have two string properties in it, so they are pretty lightweight: public class Horse { private String mId; private String mName; } I don't need these horses indexed at all. Does it sound reasonable to just store the mHorse array as a raw Text field, and force my clients to do the deserialization? Something like: public class Farm { private Text mHorsesSerialized; } then whenever the client receives a Farm instance, it has to take the raw string of horses, and split it in order to reinstantiate the list, something like: // GWT client perhaps Farm farm = rpcCall.getMyFarm(); String horsesSerialized = farm.getHorses(); String[] horseBlocks = horsesSerialized.split(","); for (int i = 0; i < horseBlocks.length; i++) { // .. continue deserializing the individual objects ... } yeah... so hopefully it would be quick to read a Farm instance from the datastore, and the serialization penalty is paid by the client, Thanks

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  • Window resolution handling without javascript

    - by Sai Sasdhar
    Is there any CSS property to deal window resolution. I created a HTML page taking total resolution width as 1424px.When I open it on different resolution I see a scroll bar & resolution of HTML does not adjust automatically. I don't want the scrollbar to be seen in maximized size of the page. Is it possible without using javascript.At the same time how to increase the resolution when itself is created in lower res.

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  • Exceptions over remote methods

    - by Andrei Vajna II
    What are the best practices for exceptions over remote methods? I'm sure that you need to handle all exceptions at the level of a remote method implementation, because you need to log it on the server side. But what should you do afterwards? Should you wrap the exception in a RemoteException (java) and throw it to the client? This would mean that the client would have to import all exceptions that could be thrown. Would it be better to throw a new custom exception with fewer details? Because the client won't need to know all the details of what went wrong. What should you log on the client? I've even heard of using return codes(for efficiency maybe?) to tell the caller about what happened. The important thing to keep in mind, is that the client must be informed of what went wrong. A generic answer of "Something failed" or no notification at all is unacceptable. And what about runtime (unchecked) exceptions?

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  • Handling a Long Running jsp request on the server using Ajax and threads

    - by John Blue
    I am trying to implement a solution for a long running process on the server where it is taking about 10 min to process a pdf generation request. The browser bored/timesout at the 5 mins. I was thinking to deal with this using a Ajax and threads. I am using regular javascript for ajax. But I am stuck with it. I have reached till the point where it sends the request to the servlet and the servlet starts the thread.Please see the below code public class HelloServlet extends javax.servlet.http.HttpServlet implements javax.servlet.Servlet { protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { System.out.println("POST request!!"); LongProcess longProcess = new LongProcess(); longProcess.setDaemon(true); longProcess.start(); request.getSession().setAttribute("longProcess", longProcess); request.getRequestDispatcher("index.jsp").forward(request, response); } } class LongProcess extends Thread { public void run() { System.out.println("Thread Started!!"); while (progress < 10) { try { sleep(2000); } catch (InterruptedException ignore) {} progress++; } } } Here is my AJax call <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html><head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>My Title</title> <script language="JavaScript" > function getXMLObject() //XML OBJECT { var xmlHttp = false; xmlHttp = new XMLHttpRequest(); //For Mozilla, Opera Browsers return xmlHttp; // Mandatory Statement returning the ajax object created } var xmlhttp = new getXMLObject(); //xmlhttp holds the ajax object function ajaxFunction() { xmlhttp.open("GET","HelloServlet" ,true); xmlhttp.onreadystatechange = handleServerResponse; xmlhttp.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded'); xmlhttp.send(null); } function handleServerResponse() { if (xmlhttp.readyState == 4) { if(xmlhttp.status == 200) { document.forms[0].myDiv.value = xmlhttp.responseText; setTimeout(ajaxFunction(), 2000); } else { alert("Error during AJAX call. Please try again"); } } } function openPDF() { document.forms[0].method = "POST"; document.forms[0].action = "HelloServlet"; document.forms[0].submit(); } function stopAjax(){ clearInterval(intervalID); } </script> </head> <body><form name="myForm"> <table><tr><td> <INPUT TYPE="BUTTON" NAME="Download" VALUE="Download Queue ( PDF )" onclick="openPDF();"> </td></tr> <tr><td> Current status: <div id="myDiv"></div>% </td></tr></table> </form></body></html> But I dont know how to proceed further like how will the thread communicate the browser that the process has complete and how should the ajax call me made and check the status of the request. Please let me know if I am missing some pieces. Any suggestion if helpful.

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  • unhandled errors in php

    - by lexus
    How can I know during runtime that my code threw a Warning? example try { echo (25/0); } catch (exception $exc) { echo "exception catched"; } throws a "Warning: Division by zero" error that i can not handle on my code.

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  • Handling multiple media queries in Sass with Twitter Bootstrap

    - by Keith
    I have a Sass mixin for my media queries based on Twitter Bootstrap's responsive media queries: @mixin respond-to($media) { @if $media == handhelds { /* Landscape phones and down */ @media (max-width: 480px) { @content; } } @else if $media == small { /* Landscape phone to portrait tablet */ @media (max-width: 767px) {@content; } } @else if $media == medium { /* Portrait tablet to landscape and desktop */ @media (min-width: 768px) and (max-width: 979px) { @content; } } @else if $media == large { /* Large desktop */ @media (min-width: 1200px) { @content; } } @else { @media only screen and (max-width: #{$media}px) { @content; } } } And I call them throughout my SCSS file like so: .link { color:blue; @include respond-to(medium) { color: red; } } However, sometimes I want to style multiple queries with the same styles. Right now I'm doing them like this: .link { color:blue; /* this is fine for handheld and small sizes*/ /*now I want to change the styles that are cascading to medium and large*/ @include respond-to(medium) { color: red; } @include respond-to(large) { color: red; } } but I'm repeating code so I'm wondering if there is a more concise way to write it so I can target multiple queries. Something like this so I don't need to repeat my code (I know this doesn't work): @include respond-to(medium, large) { color: red; } Any suggestions on the best way to handle this?

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  • Event is causing an error, but I can't catch the exception

    - by proudgeekdad
    A developer has created a custom control in ASP.NET using VB.NET. The custom control uses a repeater. In certain scenarios, the rpt_ItemDataBound event is encountering a data error. My goal is rather than having the user see the yellow screen of death, give the user a friendlier error explaining exactly what the data error is. I figured I would be able to use a Try/Catch block as shown below throw the exception, however, it appears that the event has nowhere to be thrown to and stops executing at the "End Try" line. Protected Sub rpt_ItemDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.RepeaterItemEventArgs) Handles rpt1.ItemDataBound, rpt2.ItemDataBound Try ProcessBadData... Catch ex As Exception Throw ex End Try End Sub In VB.NET, I can find where the repeater's DataSource is being set, however, I can not find a DataBind event. Any ideas how I can capture the exception in this ASCX control so I can report it to the user?

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  • Centralizing Messagebox handling for application

    - by DRapp
    I'm wondering how others deal with trying to centralize MessageBox function calling. Instead of having long text embedded all over the place in code, in the past (non .net language), I would put system and application base "messagebox" type of messages into a database file which would be "burned" into the executable, much like a resource file in .Net. When a prompting condition would arise, I would just do call something like MBAnswer = MyApplication.CallMsgBox( IDUserCantDoThat ) then check the MBAnswer upon return, such as a yes/no/cancel or whatever. In the database table, I would have things like what the messagebox title would be, the buttons that would be shown, the actual message, a special flag that automatically tacked on a subsequent standard comment like "Please contact help desk if this happens.". The function would call the messagebox with all applicable settings and just return back the answer. The big benefits of this was, one location to have all the "context" of messages, and via constants, easier to read what message was going to be presented to the user. Does anyone have a similar system in .Net to do a similar approach, or is this just a bad idea in the .Net environment.

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  • WPF button click in C# code

    - by KMC
    I have an array of button which is dynamically generated at run time. I have the function for button click in my code, but I can't find a way to set the button's click name in code. So, what is the code equivalent for XAML: <Button x:Name="btn1" Click="btn1_Click"> Or, what should I place for "????" in the following Code: Button btn = new Button()btn.Name = "btn1";btn.???? = "btn1_Click";

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  • Proper exceptions to use for nulls

    - by user200295
    In the following example we have two different exceptions we want to communicate. //constructor public Main(string arg){ if(arg==null) throw new ArgumentNullException("arg"); Thing foo=GetFoo(arg); if(foo==null) throw new NullReferenceException("foo is null"); } Is this the proper approach for both exception types?

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  • Why vba doesnt handling Error 2042

    - by Jonathan Raul Tapia Lopez
    I have a variable "fila" with a full line with excel's values; The problem is when in excel I have --#N/A-- vba take that value like "Error 2042" and I cannot asign that value to "valor" and produce me an error, until this point everything is ok, now I am trying to define a "On error goto" for go to the "next" iteration in the loop "for", but I dont know Why vba doesnt handle the error. Do While Not IsEmpty(ActiveCell) txt = ActiveCell.Value2 cell = ActiveCell.Offset(0, 1).Value2 fila = Range("C20:F20") For j = 1 To UBound(fila, 2) On Error GoTo Siguiente If Not IsEmpty(fila(1, j)) Then valor = fila(1, j) cmd = Cells(1, j + 2).Value2 devolver = function1(cmd, txt, cell, valor) arrayDevolver(p) = devolver p = p + 1 End If Siguiente: Next Loop '

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  • Validating event usurps button click on Windows Form

    - by triskelion
    I have a ComboBox and a Save button on my Windows Form. When I change the selected value in the ComboBox then click the Save button, the ComboBox validating event fires but the button click is lost. When the selected value is valid this results in the user thinking they have saved the change when in fact they have not. Why is the button click lost if the ComboBox is valid? Is there a work around?

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  • Browser not handling exception from AJAX panel, ASP.NET c#

    - by Grant
    Hi, i am having trouble catching errors in an AJAX panel. Even when i throw an exception in the c# code behind the front end completely ignores it. Here is the code i have setup, can anyone see why? I ideally want to show a js alert window on error. Code Behind: protected void btnX_Click(object sender, EventArgs e) { throw new ApplicationException("test"); } protected void ScriptManager_AsyncPostBackError(object sender, AsyncPostBackErrorEventArgs e) { ScriptManager.AsyncPostBackErrorMessage = e.Exception.Message; } Markup: <script type="text/javascript" language="javascript"> Sys.WebForms.PageRequestManager.getInstance().add_endRequest(EndRequestHandler); function EndRequestHandler(sender, e) { window.alert(e.get_error().name); } </script> <asp:ScriptManager ID="ScriptManager" runat="server" AllowCustomErrorsRedirect="true" OnAsyncPostBackError="ScriptManager_AsyncPostBackError" />

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  • .net exception pool

    - by javier
    I want to create a mecanism in a large .net application to handle all the exceptions in the application, and to save the error messages (in db or log file) so these errors can be fixed, and so we are aware of the problems in the application. Does anyone know a good way of creating a library to handle and process all the exceptions?. Are there any tools around that can simplify my task. What aproach would you suggest me to take.... If you previously implemented something similar to what I want to do, I do want to heard from you Thanks all

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  • 'Advanced' Console Application

    - by keynesiancross
    Hi all, I'm not sure if this question has been answered elsewhere and I can't seem to find anything through google that isn't a "Hello World" example... I'm coding in C# .NET 4.0. I'm trying to develop a console application that will open, display text, and then wait for the user to input commands, where the commands will run particular business logic. For example: If the user opens the application and types "help", I want to display a number of statements etc etc. I'm not sure how to code the 'event handler' for user input though. Hopefully this makes sense. Any help would be much appreciated! Cheers.

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  • How to implement event notification mechanism in AIR

    - by nxhoaf
    Do you know how to implement event notification mechanism in AIR ? For simplicity, consider an example: I want to build two applications: "television" and "remote". Among them, television is implemented using AIR. For the "television" I want to use my remote to send message to the television. How must I do to implement "television" in such way that, it runs in waiting mode and whenever it receives a message from "remote", it will process the message and make a suitable action (i.e. change channel, increase volume...). Thank you in advance.

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