Platform: WPF (.NET 4.5).
In order to check Internet connection as fast as it's possible I use this function:
[DllImport("wininet.dll")]
public extern static bool InternetCheckConnection(string lpszUrl, int dwFlags, int dwReserved);
The problem is that if I'm connected to the Internet and my program is executing InternetCheckConnection, it returns true (as expected) BUT if than I sleep the program for a moment and during this moment I disconnect my computer from the Internet and after that I check connection once again, than I have still true returned!
Why?!
I've prepared code that presents the problem:
using System;
using System.Runtime.InteropServices;
using System.Threading;
namespace InternetCheckConnectionTest
{
class Program
{
[DllImport("wininet.dll")]
public extern static bool InternetCheckConnection(string lpszUrl, int dwFlags, int dwReserved);
static void Main(string[] args)
{
string www = "http://www.google.com/";
Console.WriteLine("Checking connection...");
bool connected = InternetCheckConnection(www, 1, 0);
Console.WriteLine("Connection check returned " + connected.ToString());
TimeSpan ts = new TimeSpan(0, 0, 20);
Console.WriteLine("\nYou have " + ts.TotalSeconds.ToString() + " seconds to (dis)connect from/to the Internet.\n");
Thread.Sleep(ts);
Console.WriteLine("Checking connection once again...");
connected = InternetCheckConnection(www, 1, 0);
Console.WriteLine("Connection (2nd) check returned " + connected.ToString());
}
}
}
Before starting this program make sure that you are connected to the Internet. After this message:
You have 20 seconds to (dis)connect from/to the Internet.
disconnect from the Internet. You'll see that InternetCheckConnection(www, 1, 0) returns True even if you are disconnected from the Internet. The question is why?
Related
I'm adding some code to an app that will launch another app if it isn't already running, or if it is, bring it to the front. This requires a small amount of interop/WinAPI code, which I've gotten examples for from other sites but can't seem to get to work in Win7.
If the window is in some visible state, then the API's SetForegroundWindow method works like a treat (and this would be the main case, as per company policy if the external app is running it should not be minimized). However, if it is minimized (exceptional but important as my app will appear to do nothing in this case), neither this method nor ShowWindow/ShowWindowAsync will actually bring the window back up from the taskbar; all of the methods simply highlight the taskbar button.
Here's the code; most of it works just fine, but the call to ShowWindow() (I've also tried ShowWindowAsync) just never does what I want it to no matter what the command I send is:
[DllImport("user32.dll")]
private static extern int SetForegroundWindow(IntPtr hWnd);
private const int SW_SHOWNORMAL = 1;
private const int SW_SHOWMAXIMIZED = 3;
private const int SW_RESTORE = 9;
[DllImport("user32.dll")]
private static extern bool ShowWindow(IntPtr hWnd, int nCmdShow);
...
//The app is named uniquely enough that it can't be anything else,
//and is not normally launched except by this one.
//so this should normally return zero or one instance
var processes = Process.GetProcessesByName("ExternalApp.exe");
if (processes.Any()) //a copy is already running
{
//I can't currently tell the window's state,
//so I both restore and activate it
var handle = processes.First().MainWindowHandle;
ShowWindow(handle, SW_RESTORE); //GRR!!!
SetForegroundWindow(handle);
return true;
}
try
{
//If a copy is not running, start one.
Process.Start(#"C:\Program Files (x86)\ExternalApp\ExternalApp.exe");
return true;
}
catch (Exception)
{
//fallback for 32-bit OSes
Process.Start(#"C:\Program Files\ExternalApp\ExternalApp.exe");
return true;
}
I've tried SHOWNORMAL (1), SHOWMAXIMIZED (3), RESTORE (9), and a couple other sizing commands, but nothing seems to do the trick. Thoughts?
EDIT: I found an issue with some of the other code I had thought was working. The call to GetProcessesByName() was not finding the process because I was looking for the executable name, which was not the process name. That caused the code I thought was running and failing to actually not execute at all. I thought it was working because the external app will apparently also detect that a copy is already running and try to activate that current instance. I dropped the ".exe" from the process name I search for and now the code executes; however that seems to be a step backwards, as now the taskbar button isn't even highlighted when I call ShowWindow[Async]. So, I now know that neither my app, nor the external app I'm invoking, can change the window state of a different instance programmatically in Win7. What's goin' on here?
Working code using FindWindow method:
[DllImport("user32.dll")]
public static extern IntPtr FindWindow(string className, string windowTitle);
[DllImport("user32.dll")]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool ShowWindow(IntPtr hWnd, ShowWindowEnum flags);
[DllImport("user32.dll")]
private static extern int SetForegroundWindow(IntPtr hwnd);
[DllImport("user32.dll")]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool GetWindowPlacement(IntPtr hWnd, ref Windowplacement lpwndpl);
private enum ShowWindowEnum
{
Hide = 0,
ShowNormal = 1, ShowMinimized = 2, ShowMaximized = 3,
Maximize = 3, ShowNormalNoActivate = 4, Show = 5,
Minimize = 6, ShowMinNoActivate = 7, ShowNoActivate = 8,
Restore = 9, ShowDefault = 10, ForceMinimized = 11
};
private struct Windowplacement
{
public int length;
public int flags;
public int showCmd;
public System.Drawing.Point ptMinPosition;
public System.Drawing.Point ptMaxPosition;
public System.Drawing.Rectangle rcNormalPosition;
}
private void BringWindowToFront()
{
IntPtr wdwIntPtr = FindWindow(null, "Put_your_window_title_here");
//get the hWnd of the process
Windowplacement placement = new Windowplacement();
GetWindowPlacement(wdwIntPtr, ref placement);
// Check if window is minimized
if (placement.showCmd == 2)
{
//the window is hidden so we restore it
ShowWindow(wdwIntPtr, ShowWindowEnum.Restore);
}
//set user's focus to the window
SetForegroundWindow(wdwIntPtr);
}
You can use it by calling BringWindowToFront().
I always have one instance of the application running so if you can have several open instances simultaneously you might want to slightly change the logic.
... Apparently you cannot trust the information a Process gives you.
Process.MainWindowHandle returns the window handle of the first window created by the application, which is USUALLY that app's main top-level window. However, in my case, a call to FindWindow() shows that the handle of the actual window I want to restore is not what MainWindowHandle is pointing to. It appears that the window handle from the Process, in this case, is that of the splash screen shown as the program loads the main form.
If I call ShowWindow on the handle that FindWindow returned, it works perfectly.
What's even more unusual is that when the window's open, the call to SetForegroundWindow(), when given the process's MainWindowHandle (which should be invalid as that window has closed), works fine. So obviously that handle has SOME validity, just not when the window's minimized.
In summary, if you find yourself in my predicament, call FindWindow, passing it the known name of your external app's main window, to get the handle you need.
I had the same problem. The best solution I have found is to call ShowWindow with the flag SW_MINIMIZE, and then with SW_RESTORE. :D
Another possible solution:
// Code to display a window regardless of its current state
ShowWindow(hWnd, SW_SHOW); // Make the window visible if it was hidden
ShowWindow(hWnd, SW_RESTORE); // Next, restore it if it was minimized
SetForegroundWindow(hWnd); // Finally, activate the window
from comments at: http://msdn.microsoft.com/en-us/library/ms633548%28VS.85%29.aspx
Tray calling ShowWindow(handle, SW_RESTORE); after SetForegroundWindow(handle);
This might solve your problem.
It sounds like you're trying to perform an action that has the same result as alt-tabbing, which brings the window back if it was minimized while "remembering" if it was maximized.
NativeMethods.cs:
using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
// Specify your namespace here
namespace <your.namespace>
{
static class NativeMethods
{
// This is the Interop/WinAPI that will be used
[DllImport("user32.dll")]
static extern void SwitchToThisWindow(IntPtr hWnd, bool fUnknown);
}
}
Main code:
// Under normal circumstances, only one process with one window exists
Process[] processes = Process.GetProcessesByName("ExternalApp.exe");
if (processes.Length > 0 && processes[0].MainWindowHandle != IntPtr.Zero)
{
// Since this simulates alt-tab, it restores minimized windows to their previous state
SwitchToThisWindow(process.MainWindowHandle, true);
return true;
}
// Multiple things are happening here
// First, the ProgramFilesX86 variable automatically accounts for 32-bit or 64-bit systems and returns the correct folder
// Secondly, $-strings are the C# shortcut for string.format() (It automatically calls .ToString() on each variable contained in { })
// Thirdly, if the process was able to start, the return value is not null
try { if (Process.Start($"{System.Environment.SpecialFolder.ProgramFilesX86}\\ExternalApp\\ExternalApp.exe") != null) return true; }
catch
{
// Code for handling an exception (probably FileNotFoundException)
// ...
return false;
}
// Code for when the external app was unable to start without producing an exception
// ...
return false;
I hope this provides a much simpler solution.
(General Rule: If a string value is ordinal, i.e. it belongs to something and isn't just a value, then it is better to get it programmatically. You'll save yourself a lot of trouble when changing things. In this case, I'm assuming that the install location can be converted to a global constant, and the .exe name can be found programmatically.)
I know its too late, still my working code is as follows so that someone later can get quick help :)
using System.Runtime.InteropServices;
using System.Diagnostics;
[DllImport("user32.dll")]
static extern bool SetForegroundWindow(IntPtr hWnd);
[DllImport("user32.dll")]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool ShowWindow(IntPtr hWnd, int nCmdShow);
[DllImport("user32.dll", EntryPoint = "FindWindow")]
public static extern IntPtr FindWindowByCaption(IntPtr ZeroOnly, string lpWindowName);
private static void ActivateApp(string processName)
{
Process[] p = Process.GetProcessesByName(processName);
if (p.Length > 0)
{
IntPtr handle = FindWindowByCaption(IntPtr.Zero, p[0].ProcessName);
ShowWindow(handle, 9); // SW_RESTORE = 9,
SetForegroundWindow(handle);
}
}
ActivateApp(YOUR_APP_NAME);
Actually, FindWindowByCaption is the key here, this method collects the window handle correctly when app is running silently in the system tray and also when app is minimized.
In our software we occasionally use sending WM_HELP via SendMessage api to a control. Normally the "HelpRequested" event is then fired (or up in the parent hierarchy until an event handler is registered).
We included an external complex 3d visualization library called "VTK" and after that, this Message passing does not work anymore. In trying to track down the problem I used Spy++ to see whether the message is shown there and realized that running spy++ is generating the same problem! (Also without any vtk stuff). It can be shown with this little Program:
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Windows.Forms;
namespace TestHelp
{
public partial class Form1 : Form
{
[System.Runtime.InteropServices.StructLayout(System.Runtime.InteropServices.LayoutKind.Sequential)]
struct HelpInfo
{
public uint cbSize;
public int iContextType;
public int iCtrlID;
public int hItemHandle;
public int dwContextID;
public int MouseX;
public int MouseY;
}
[DllImport("user32.DLL", EntryPoint = "SendMessage", SetLastError = true)]
private static extern int SendHelpMessage(int hWnd, uint Msg, uint wparam, ref HelpInfo helpinfo);
public static void RaiseHelp(Control ctrl)
{
HelpInfo helpInfo = new HelpInfo
{
cbSize = 48,
iContextType = 1,
iCtrlID = 0,
hItemHandle = ctrl.Handle.ToInt32(),
dwContextID = 0,
MouseX = 10,
MouseY = 10,
};
var res = SendHelpMessage(ctrl.Handle.ToInt32(), 0x053, 0, ref helpInfo);
Debug.WriteLine($"SendMessage returns:{res}");
}
public Form1()
{
InitializeComponent();
button1.HelpRequested += (sender, hlpevent) => { Trace.WriteLine("HelpRequested called"); };
timer = new Timer() {Interval = 1000, Enabled = true};
timer.Tick += (sender, args) => RaiseHelp(button1);
}
private Timer timer;
}
}
The form only contains a single button named "button1".
When you start in debugger you see "HelpRequested called" in Output window every second. When you start Spy++, nothing more, just start, it will stop that! When closing spy++ it continues to work again. Does everyone have an explanation for this behaviour? What is Spy++ doing with my application? My hope is that the same mechanism is responsible for the same problem with vtk (there only in-process, though).
Of course, using win32 api SendMessage may seem inappropriate for a WinForms application, but we don't have time now to refactor all that stuff, and I nevertheless want to understand whats happening here!
Btw.: user window message are not affected (WM_USER to 0x7FFF), checked by overriding WndProc. WM_HELP also does not show in WndProc while spy++ is running, btw.
Problem was wrong size for HelpInfo.cbSize. In 64-bit mode it is 40, in 32-bit it is 28. Yes I should use sizeof(), but this is only allowed in "unsafe" mode.
But how the hell spy++ or VTK interfere with this?
When checkpointing is turned on a simple CEP loop pattern
private Pattern<Tuple2<Integer, SimpleBinaryEvent>, ?> alertPattern = Pattern.<Tuple2<Integer, SimpleBinaryEvent>>begin("start").where(checkStatusOn)
.followedBy("middle").where(checkStatusOn).times(2)
.next("end").where(checkStatusOn).within(Time.minutes(5))
I see failures.
SimpleBinaryEvent is
public class SimpleBinaryEvent implements Serializable {
private int id;
private int sequence;
private boolean status;
private long time;
public SimpleBinaryEvent(int id, int sequence, boolean status , long time) {
this.id = id;
this.sequence = sequence;
this.status = status;
this.time = time;
}
public int getId() {
return id;
}
public int getSequence() {
return sequence;
}
public boolean isStatus() {
return status;
}
public long getTime() {
return time;
}
#Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
SimpleBinaryEvent that = (SimpleBinaryEvent) o;
if (getId() != that.getId()) return false;
if (isStatus() != that.isStatus()) return false;
if (getSequence() != that.getSequence()) return false;
return getTime() == that.getTime();
}
#Override
public int hashCode() {
//return Objects.hash(getId(),isStatus(), getSequence(),getTime());
int result = getId();
result = 31 * result + (isStatus() ? 1 : 0);
result = 31 * result + getSequence();
result = 31 * result + (int) (getTime() ^ (getTime() >>> 32));
return result;
}
#Override
public String toString() {
return "SimpleBinaryEvent{" +
"id='" + id + '\'' +
", status=" + status +
", sequence=" + sequence +
", time=" + time +
'}';
}
}
failure cause:
Caused by: java.lang.Exception: Could not materialize checkpoint 2 for operator KeyedCEPPatternOperator -> Map (1/1).
... 6 more
Caused by: java.util.concurrent.ExecutionException: java.lang.IllegalStateException: Could not find id for entry: SharedBufferEntry(ValueTimeWrapper((1,SimpleBinaryEvent{id='1', status=true, sequence=95, time=1505503380000}), 1505503380000, 0),....
I am sure I have the equals() and hashCode() implemented the way it should be. I have tried the Objects.hashCode too. In other instances I have had CircularReference ( and thus stackOverflow ) on SharedBuffer.toString(), which again points to issues with references ( equality and what not ). Without checkpointing turned on it works as expected. I am running on a local cluster. Is CEP production ready ?
I am using 1.3.2 Flink
Thanks a lot for trying out the library and reporting this!
The library is under active development as more and more features are added to it. The 1.3 was the first release of the library with such rich semantics, so we expect to see 1) how people use it and 2) if there are any bugs. So I would say that it is not 100% production-ready but it is not far.
Now for the problem at hand, I suppose you are using RocksDB for checkpointing, right? The reason I am assuming that is that with RocksDB, at each watermark (in event time) you deserialize the necessary state (e.g. the NFA), process some events and then serialize it again before putting it back in RocksDB.
This is not the case for the filesystem state backend, where you only serialize the state upon checkpointing and you read it and deserialize it only upon recovery. So in this case, given that you said that without checkpointing your job works fine, you would only see this problem only after recovering from a failure.
The root of the problem can be either that equals()/hashcode() is buggy (which does not seem to be the case), or there is a problem on the way we serialize/deserialize the CEP state.
Could you also provide a minimal input sequence of events that produce this to happen? This will be really helpful in order to reproduce the problem.
Thanks a lot,
Kostas
I am developing a windows form application. I have a requirement, need ping the system ip address with parameters. like ping IP Address -n 1.
I am Unable to pass the parameter using ping.send function.
Any one can help me.
use Ping class. This provides a more organized approach
using System;
using System.Net;
using System.Net.NetworkInformation;
using System.Text;
namespace Examples.System.Net.NetworkInformation.PingTest
{
public class PingExample
{
// args[0] can be an IPaddress or host name.
public static void Main (string[] args)
{
Ping pingSender = new Ping ();
PingOptions options = new PingOptions ();
// Use the default Ttl value which is 128,
// but change the fragmentation behavior.
options.DontFragment = true;
// Create a buffer of 32 bytes of data to be transmitted.
string data = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa";
byte[] buffer = Encoding.ASCII.GetBytes (data);
int timeout = 120;
PingReply reply = pingSender.Send (args[0], timeout, buffer, options);
if (reply.Status == IPStatus.Success)
{
Console.WriteLine ("Address: {0}", reply.Address.ToString ());
Console.WriteLine ("RoundTrip time: {0}", reply.RoundtripTime);
Console.WriteLine ("Time to live: {0}", reply.Options.Ttl);
Console.WriteLine ("Don't fragment: {0}", reply.Options.DontFragment);
Console.WriteLine ("Buffer size: {0}", reply.Buffer.Length);
}
}
}
}
You can spam a cmd process and get its output.
ProcessStartInfo processInfo = new ProcessStartInfo("cmd");
processInfo.RedirectStandardInput = true;
processInfo.RedirectStandardOutput = true;
processInfo.UseShellExecute = false;
processInfo.CreateNoWindow = true;
Process process = Process.Start(processInfo);
process.StandardInput.WriteLine("ping 127.0.0.1 -n 1 -i 10");
process.StandardInput.Close();
string answer = process.StandardOutput.ReadToEnd();
process.WaitForExit();
process.Close()
Console.WriteLine(answer);
I have an application that downloads a video file that is roughly 6mb
I am trying to run this application on a Blackberry Curve 9360, which has 32mb of "media" storage
Sometimes this application runs and is able to download the video with no problems, however other times part way thru downloading the download process fails with an IO exception that states: "There is not enough free memory on the file system to complete this action"
after it fails in this manner I can open up the BlackBerry Desktop software and check the files section and see that the device is indeed reporting that 32/32 mb are full.
If I then restart the device with alt-shift-del and open up blackberry desktop software again the used space has shrunk back down to only 5-6 / 32mb full
Sometimes at this point I am able to run my application now and have it succeed the download, but other times it again gives me the same storage full error. The only thing I can notice that seems like it might be affecting whether or not it fails is how long the download takes total (i.e. it succeeds on wifi, and on good 3g signal and fails on poorer 3g signal, but this is anecdotal at best)
I have used this exact same application on a few different blackberry devices, including a few other Curve devices with the same storage size, and never run into this problem before.
My question is: Has anyone seen a BlackBerry curve device behave in such a way that it will report an incorrect storage space that gets fixed by a reboot?
And is there anything about this download code that could be causing this behavior?
class DownloadThread extends Thread {
public void run()
{
HttpConnection httpConn = null;
InputStream is = null;
try{
httpConn = (HttpConnection)Connector.open(videoUrl + ";interface=wifi");
is = httpConn.openInputStream();
}catch(IOException e){
try{
httpConn = (HttpConnection)Connector.open(videoUrl);
is = httpConn.openInputStream();
}catch(IOException ioe){
System.out.println("891: "+e.toString());
}
}
try{
if (!videoFconn.exists())
videoFconn.create();
else{
videoFconn.delete();
videoFconn.create();
}
OutputStream os = videoFconn.openOutputStream();
lengthOfWebFile = httpConn.getLength();
total = 0;
System.out.println("##################### length of web file = " + lengthOfWebFile + " #################");
byte data[] = new byte[256];
while ((count = is.read(data)) != -1) {
total += count;
progress = (int)(total*100/lengthOfWebFile);
if(model.getValue() < progress){
UiApplication.getUiApplication().invokeLater(new Runnable()
{
public void run()
{
EmbeddedMediaScreen.this.model.setValue(progress);
}
});
}
//write this chunk
os.write(data, 0, count);
Thread.yield();
}
os.flush();
os.close();
is.close();
httpConn.close();
lengthOfLocalFile = videoFconn.fileSize();
System.out.println("###################### Local Length = " + lengthOfLocalFile + "#####################");
if(lengthOfLocalFile == lengthOfWebFile){
amDownloading = false;
startVideo();
}else{
downloadVideo();
}
}catch(FileNotFoundException fnf){
}catch(IOException e){
//ScreenSaverActivity.errorDialog("975: "+e.toString());
System.out.println("980: "+e.toString());
//e.printStackTrace();
}catch(NullPointerException npe){
System.out.println("983: "+npe.toString());
} /*catch (InterruptedException e) {
// TODO Auto-generated catch block
System.out.println(e.getMessage());
}*/
}
public synchronized void postProgress(final int p){
UiApplication.getUiApplication().invokeLater(new Runnable()
{
public void run()
{
//Set the progress bar
EmbeddedMediaScreen.this.model.setValue(p);
}
});
}
}