I have two windows applications. First one a windows forms application. The second one a console application. I have to send a message from the console application to the forms application. I registered broadcast message and using ::PostMessage function was able to send a numeric message to the forms application. But I am not able to send string message. Please find my code below:-
// Sending Message (Console Application)
#define RT_UI_MSG (WM_USER+1)
UINT msg_id = RegisterWindowMessage("Test-UI");
LPTSTR lpszString = "Hello";
COPYDATASTRUCT cds;
cds.dwData = 1; // can be anything
cds.cbData = sizeof(TCHAR) * (_tcslen(lpszString) + 1);
cds.lpData = &lpszString;
::PostMessage(HWND_BROADCAST, msg_id, WM_COPYDATA, (LPARAM)(LPVOID)&cds);
// Receiving Message (Forms Application)
BEGIN_MESSAGE_MAP(CRTUIDlg, CDialogEx)
ON_WM_PAINT()
ON_WM_QUERYDRAGICON()
ON_BN_CLICKED(IDOK, &CRTUIDlg::OnBnClickedOk)
ON_REGISTERED_MESSAGE(temp, OnRTUIMsg)
ON_BN_CLICKED(IDC_BUTTON1, &CRTUIDlg::OnBnClickedButton1)
END_MESSAGE_MAP()
UINT temp = RegisterWindowMessage(L"Test-UI");
LRESULT CRTUIDlg::OnRTUIMsg(WPARAM wParam, LPARAM lParam)
{
COPYDATASTRUCT* pcds = (COPYDATASTRUCT*)lParam;
if (pcds->dwData == 1)
{
LPCTSTR lpszString = (LPCTSTR)(pcds->lpData);
// do something with lpszString...
}
return 0;
}
Kindly help me understand what I am doing wrong and get this working
There is no way to PostMessage a WM_COPYDATA. The system needs to know when to free the internal buffer used to marshal the data. And this is known only when you send, not when you post a message.
See Why can't I PostMessage the WM_COPYDATA message, but I can SendMessageTimeout it with a tiny timeout?
WM_COPYDATA states the following:
"The data being passed must not contain pointers or other references to objects not accessible to the application receiving the data."
But you are including a pointer to the source application heap (lpszString) into the structure which is not supported, because the heap of the source application is not accessible to the target application. WM_COPYDATA will copy that pointer as is, it will not copy the string referenced by the pointer.
I suggest looking at the example in WM_COPYDATA, the example seems to do what you need but instead of passing a string from the heap, it copies the string into the stack using a char array.
This is the link to the example:
https://msdn.microsoft.com/en-us/library/windows/desktop/ms649009(v=vs.85).aspx
Related
I am try to figure out if the Winsock UDP way of sending and recieving datagrams has an option to get a respond back to the sendto() like a function.
To make it clear lets say that i have a function that uses UDP to send a message
and needs to return back a true or false state
Since this function is using UDP to send a message, the application that recieves the message needs to execute a specific command and send back the returned value of true false to the UDP sender, so in that way the function from the control program will know that the function was properly executed or not.
Application 1 :
bool Test(){
functionToRun = "checkandRespond";
respond = sendto(....);
if(respond == "true"){
Brespond = true;
}else{
Brespond = false;
}
return Brespond;
}
Application 2 :
bool check(){
return true;
}
DWORD WINAPI IncomingMessages(){
recvfrom(....)
//run the function requested e.x.
bool respondto1App = check();
sendback the respondto1App boolean to string to Application 1
}
Is there any way to get back an instant respond like a function needs between two applications using UDP ?
NOTE : i don`t want to know if the sendto() command has send the message to the other application successfully, i want to get the respond back from the second application like if i was running the check() function from application 1.
Thanks in advance for any help on the issue
I have a managed application that has to read binary data from proprietary files with an unmanaged third-party Win32-only DLL. I keep infrequent crashes where my application simply exits without any exception etc. In the application log in the system, I get the well-known exit code 80131506. Directly after this entry, I get an "Application error" where the faulting module is clr.dll.
In my managed code, where I have the control, I added lots of debug logging (Thanks, log4net) and found out that it crashes at this piece of code:
double* buf = new double[bufSize];
try {
for(SliceIterator iter = numericSlice.begin(); valuesLeft > 0;) {
size_t transferred;
numericSlice.getValuesToArray(iter, buf, bufSize, transferred); // transferred is set to the number of values which were written to the buf array, iter is advanced automatically
valuesLeft -= transferred;
array<double>^ out = gcnew array<double>(transferred);
System::Runtime::InteropServices::Marshal::Copy(IntPtr((void*)buf), out, 0, transferred); // <- crashes here
valueReadCallback(domainId, channelId, out);
}
} finally {
delete buf;
}
The SliceIterator and numericSlice with its getValuesToArray method come from the unmanaged DLL, and what I want to accomplish is that I want to drag the contents of the buf array to the out array which is a managed one. The valueReadCallback is a System.Action that I get into the method where this code is called as a parameter. I have to do it this complicated because the vendor of the third party DLL implemented his own reference counting which goes wonky when I use it in managed code. So I have to stay in just one scope while I do all the nasty unmanaged stuff, collect everything and somehow blast it out to the managed side while still in there.
Now, my questions are: Am I doing this right? Does the Marshal::Copy really do a deep copy or just some "clever" re-referencing?
In my test application I can see messages that were processed with an exception being automatically inserted into the default EasyNetQ_Default_Error_Queue, which is great. I can then successfully dump or requeue these messages using the Hosepipe, which also works fine, but requires dropping down to the command line and calling against both Hosepipe and the RabbitMQ API to purge the queue of retried messages.
So I'm thinking the easiest approach for my application is to simply subscribe to the error queue, so I can re-process them using the same infrastructure. But in EastNetQ, the error queue seems to be special. We need to subscribe using a proper type and routing ID, so I'm not sure what these values should be for the error queue:
bus.Subscribe<WhatShouldThisBe>("and-this", ReprocessErrorMessage);
Can I use the simple API to subscribe to the error queue, or do I need to dig into the advanced API?
If the type of my original message was TestMessage, then I'd like to be able to do something like this:
bus.Subscribe<ErrorMessage<TestMessage>>("???", ReprocessErrorMessage);
where ErrorMessage is a class provided by EasyNetQ to wrap all errors. Is this possible?
You can't use the simple API to subscribe to the error queue because it doesn't follow EasyNetQ queue type naming conventions - maybe that's something that should be fixed ;)
But the Advanced API works fine. You won't get the original message back, but it's easy to get the JSON representation which you could de-serialize yourself quite easily (using Newtonsoft.JSON). Here's an example of what your subscription code should look like:
[Test]
[Explicit("Requires a RabbitMQ server on localhost")]
public void Should_be_able_to_subscribe_to_error_messages()
{
var errorQueueName = new Conventions().ErrorQueueNamingConvention();
var queue = Queue.DeclareDurable(errorQueueName);
var autoResetEvent = new AutoResetEvent(false);
bus.Advanced.Subscribe<SystemMessages.Error>(queue, (message, info) =>
{
var error = message.Body;
Console.Out.WriteLine("error.DateTime = {0}", error.DateTime);
Console.Out.WriteLine("error.Exception = {0}", error.Exception);
Console.Out.WriteLine("error.Message = {0}", error.Message);
Console.Out.WriteLine("error.RoutingKey = {0}", error.RoutingKey);
autoResetEvent.Set();
return Task.Factory.StartNew(() => { });
});
autoResetEvent.WaitOne(1000);
}
I had to fix a small bug in the error message writing code in EasyNetQ before this worked, so please get a version >= 0.9.2.73 before trying it out. You can see the code example here
Code that works:
(I took a guess)
The screwyness with the 'foo' is because if I just pass that function HandleErrorMessage2 into the Consume call, it can't figure out that it returns a void and not a Task, so can't figure out which overload to use. (VS 2012)
Assigning to a var makes it happy.
You will want to catch the return value of the call to be able to unsubscribe by disposing the object.
Also note that Someone used a System Object name (Queue) instead of making it a EasyNetQueue or something, so you have to add the using clarification for the compiler, or fully specify it.
using Queue = EasyNetQ.Topology.Queue;
private const string QueueName = "EasyNetQ_Default_Error_Queue";
public static void Should_be_able_to_subscribe_to_error_messages(IBus bus)
{
Action <IMessage<Error>, MessageReceivedInfo> foo = HandleErrorMessage2;
IQueue queue = new Queue(QueueName,false);
bus.Advanced.Consume<Error>(queue, foo);
}
private static void HandleErrorMessage2(IMessage<Error> msg, MessageReceivedInfo info)
{
}
We are running on a Windows Client Platform (generally WinXP) in niche industry program that runs in a 640x480 window back to an AS/400 server. To reduce errors I want to watch for when the title bar of the program changes. Then I need to capture the keyboard entries to validate. I'll then make sure each of the entries is valid since the archaic program does no validation. I'll can then do a pop-up then warning the end-user if errors occur and to reduce/eliminate the exception reports.
My question is how can I capture the event of the application title bar change = 'string' that I need? API call? Aiming to do this in VB unless another would be notable cleaner.
WinEvents should work well here. These are lightweight events that get fired when certain UI changes take place - eg names of objects change - which includes Titlebar text changes. One benefit to this type of hook is that you can set it up to deliver the notifications back to your own process, so you don't need to deal with hooking or IPC. (It also works against both 32-bit and 64-bit processes.)
This is easiest to do in plain C/C++; but can be done in .Net (VB, C#) if you add the appropriate [DllImport]'s.
#include <windows.h>
#include <stdio.h>
#define WM_NAMECHANGED WM_APP
HWND g_hwndTarget; // window we're listening to
void CALLBACK WinEventProc(
HWINEVENTHOOK hWinEventHook,
DWORD event,
HWND hwnd,
LONG idObject,
LONG idChild,
DWORD dwEventThread,
DWORD dwmsEventTime
)
{
// Check this is the window we want. Titlebar name changes result in these
// two values (obtained by looking at some titlebar changes with the
// Accessible Event Watcher tool in the Windows SDK)
if(hwnd == g_hwndTarget && idObject == OBJID_WINDOW && idChild == CHILDID_SELF)
{
// Do minimal work here, just hand off event to mainline.
// If you do anything here that has a message loop - eg display a dialog or
// messagebox, you can get reentrancy.
PostThreadMessage(GetCurrentThreadId(), WM_NAMECHANGED, 0, 0);
}
return;
}
void ReportName(HWND hwnd)
{
WCHAR szName[128];
GetWindowText(hwnd, szName, ARRAYSIZE(szName));
wprintf(L"hwnd 0x%08lx has title: %s\n", HandleToLong(hwnd), szName);
}
int main()
{
wprintf(L"Place mouse pointer over window titlebar to report name changes for and hit return...\n");
getchar();
POINT pt;
GetCursorPos(&pt);
g_hwndTarget = WindowFromPoint(pt);
ReportName(g_hwndTarget);
// Note: this doesn't work for console windows, which are managed by CSRSS.EXE. Simplest (though not efficient) workaround for those
// is to use threadId=0 and filter by hwnd in the callback.
DWORD threadId = GetWindowThreadProcessId(g_hwndTarget, NULL);
// This says: call the callback when any UI elements in the specified thread change
// name. _OUTOFCONTEXT means deliver the notifications in this process, don't hook.
HWINEVENTHOOK hook = SetWinEventHook(EVENT_OBJECT_NAMECHANGE, EVENT_OBJECT_NAMECHANGE, NULL, WinEventProc, 0, threadId, WINEVENT_OUTOFCONTEXT);
// TODO: add error checking as appropriate.
wprintf(L"Waiting...\n");
// Thread needs to have a message loop for SetWinEventHook to work for out-of-context messages.
UINT count = 10;
MSG msg;
while(GetMessage(&msg, NULL, 0, 0))
{
if(msg.message == WM_NAMECHANGED)
{
ReportName(g_hwndTarget);
if(--count == 0)
{
break;
}
}
TranslateMessage(&msg);
DispatchMessage(&msg);
}
UnhookWinEvent(hook);
return 0;
}
Things to watch for: you might get false-positives; and if the name changes rapidly, by the time you get the first event, the name may be at the second value, so you may appear to see two events for the second value. Neither of these should be an issue if you're just using this as a trigger to check for a specified value, however.
I am assuming that you do not own the code for the target application. In this case, there's no easy "call me back when the title changes" event. You then have 2 options to do what you need, which I will outline below.
Easy but not airtight
Have your application get the main window of the target application (this should be easy enough) and poll its title every 100msec or so. When you detect a change, act accordingly.
Difficult but correct
Hook into the target application using e.g. a global CBT hook. Once your code runs in their process subclass their main window, causing all window messages to go through your code first. When your code sees a WM_SETTEXT message going to the main window, you can actively notify your "other" application on the spot using your choice of IPC. If all you need to do is just shout "hey!" to your other application, do so with an auto-reset event (it will be easiest). Of course all this points heavily to unmanaged code.
If the easy solution is not good enough and the difficult one is too much, you can try using an automation library like White (I 've never used it, so I can't really say more than that).
I am trying to understand how I would implement message framing with WCF. The goal is to create a server in WCF that can handle proprietary formats over Tcp. I can't use the net.Tcp binding because that is only for SOAP.
I need to write a custom channel that would receive messages in the following format
. An example message would be "5 abcde". In particular I am not sure how to do framing in my custom channel.
Here is some sample code
class CustomChannel: IDuplexSessionChannel
{
private class PendingRead
{
public NetworkStream Stream = null;
public byte[] Buffer = null;
public bool IsReading = false;
}
private CommunicationState state = CommunicationState.Closed;
private TcpClient tcpClient = null;
private MessageEncoder encoder = null;
private BufferManager bufferManager = null;
private TransportBindingElement bindingElement = null;
private Uri uri = null;
private PendingRead pendingRead;
public CustomChannel(Uri uri, TransportBindingElement bindingElement, MessageEncoderFactory encoderFactory, BufferManager bufferManager, TcpClient tcpClient)
{
this.uri = uri;
this.bindingElement = bindingElement;
this.tcpClient = tcpClient;
this.bufferManager = bufferManager;
state = CommunicationState.Created;
}
public IAsyncResult BeginTryReceive(TimeSpan timeout, AsyncCallback callback, object state)
{
if (this.state != CommunicationState.Opened) return null;
byte[] buffer = bufferManager.TakeBuffer(tcpClient.Available);
NetworkStream stream = tcpClient.GetStream();
pendingRead = new PendingRead { Stream = stream, Buffer = buffer, IsReading = true };
IAsyncResult result = stream.BeginRead(buffer, 0, buffer.Length, callback, state);
return result;
}
public bool EndTryReceive(IAsyncResult result, out Message message)
{
int byteCount = tcpClient.Client.EndReceive(result);
string content = Encoding.ASCII.GetString(pendingRead.buffer)
// framing logic here
Message.CreateMessage( ... )
}
}
So basically the first time around EndTryReceive could just get a piece of the message from the pending read buffer "5 ab". Then the second time around it could get the rest of the message. The problem is when EndTryReceive gets called the first time, I am forced to create a Message object, this means that there will be a partial Message going up the channel stack.
What I really want to do is to make sure that I have my full message "5 abcde" in the buffer, so that when I construct the message in EndTryReceive it is a full message.
Does anyone have any examples of how they are doing custom framing with WCF?
Thanks,
Vadim
Framing at the wire level is not something that the WCF channel model really cares about; it's pretty much up to you to handle it.
What I mean by this is that it is your responsibility to ensure that your transport channel returns "entire" messages on a receive (streaming changes that a bit, but only up to a point).
In your case, it seems you're translating receive operations on your channel directly into receive operations on the underlying socket, and that just won't do, because that won't give you a chance to enforce your own framing rules.
So really, a single receive operation on your channel might very well translate to more than one receive operation on the underlying socket, and that's fine (and you can still do all that async, so it doesn't need to affect that part).
So basically the question becomes: what's your protocol framing model look like? Wild guess here, but it looks like messages are length prefixed, with the length encoded as a decimal string? (looks annoying).
I think your best bet in that case would be to have your transport buffer incoming data (say, up to 64KB of data or whatever), and then on each receive operation check the buffer to see if it contains enough bytes to extract the length of the incoming message. If so, then either read as many bytes as necessary from the buffer, or flush the buffer and read as many bytes from the socket. You'll have to be careful as, depending on how your protocol works, I'm assuming you might end up reading partial messages before you actually need them.
I agree with the thomasr. You can find some basic inspiration in Microsoft Technology Sample "ChunkingChannel".