I'm trying out IPC with named pipes in a test application that I wrote for that purpose. I want to read a value from a pipe, but the reader doesn't seem to read anything.
I'm starting a server process and a client. The server uses a named pipe called InitPipe to tell the client a name for a new pipe for communication. After that happens, a new server process and the client get connected to the new pipe, the other server process and client get disconnected and the InitPipe reopened for new processes to communicate with the server.
The client writes data to the pipe and the new server process should read the data. That's where the problem is. The server doesn't seem to get the values off the pipe.
private void svr_task(string comPipe)
{
var server = new NamedPipeServerStream(comPipe);
write("Com-Pipe: " + comPipe); //'write' just writes to a TextBox on the UI thread
server.WaitForConnection();
write("Client connected: " + comPipe);
StreamReader reader = new StreamReader(server);
StreamWriter writer = new StreamWriter(server);
while (server.IsConnected)
{
var line = reader.ReadLine(); //the program doesn't seem to run past this line
write(line);
}
write("Client disconnected: " + comPipe);
server.Dispose();
write("Com-Pipe closed: " + comPipe);
}
private void cl_start()
{
//This is for InitPipe
var clientInit = new NamedPipeClientStream("InitPipe");
NamedPipeClientStream client = new NamedPipeClientStream("InitPipe");
clientInit.Connect();
Dispatcher.Invoke(() => stat_cl1.Content = "Initialize...");
StreamReader reader = new StreamReader(clientInit);
StreamWriter writer = new StreamWriter(clientInit);
while (clientInit.IsConnected)
{
var line = reader.ReadLine();
client = new NamedPipeClientStream(line);
clientInit.Dispose();
}
//This is where the communication with the server thread starts
client.Connect();
Dispatcher.Invoke(() => stat_cl1.Content = "Connected");
reader = new StreamReader(client);
writer = new StreamWriter(client);
while (client.IsConnected)
{
string line = Dispatcher.Invoke(() => box_cl1.Text); //read a value from a textbox (This works)
writer.Write(line);
writer.Flush();
}
client.Dispose();
Dispatcher.Invoke(() => stat_cl1.Content = "Not connected");
}
I want the server thread to receive the values from the client thread. The UI thread is not locked so that I can start another client, which can also connect to a server thread.
When debugging in VS and stepping through the code, it just runs after var line = reader.ReadLine(); and seems to never get to the next line. So that's why I think it can't read any values from the pipe. But what do I need to change? I want to output the value with write.
I ran into a similar problem. It has to do with how namedpipes work. You can either be writing to or reading from a named pipe at a time. try not attaching StreamReader and StreamWriter to the stream at the same time. I got around this by a reader stream and a writer stream separate. Also, you can use the same pipe name for multiple clients, you just have to create a new instance of server after a client connects.
Related
I have separate client and server console apps. I'm simply trying to send a string from the client to the server and have the server write the string to the console using TcpClient. I can send a single message just fine but when I throw a while loop into the client app to try and send multiple messages without closing the TcpClient, the server doesn't write anything to the console.
//Server
using (TcpClient client = listener.AcceptTcpClient())
{
NetworkStream ns = client.GetStream();
byte[] buffer = new byte[1024];
while (true)
{
if (ns.DataAvailable)
{
int bytesRead = 0;
string dataReceived = "";
do
{
bytesRead = ns.Read(buffer, 0, buffer.Length);
dataReceived += Encoding.UTF8.GetString(buffer, 0, bytesRead);
}
while (bytesRead > 0);
Console.WriteLine($"Message:{ dataReceived }\n");
}
}
}
//Client
using (TcpClient client = new TcpClient(hostname, port))
{
if (client.Connected)
{
Console.WriteLine("Connected to server");
NetworkStream ns = client.GetStream();
string message = "";
//Removing this while loop I can send a single message that the server will write to console
//but with the loop present the server does not write anything
while (true)
{
message = Console.ReadLine();
byte[] messageBytes = UTF8Encoding.UTF8.GetBytes(message);
ns.Write(messageBytes);
Console.WriteLine($"Message Sent! ({ messageBytes.Length } bytes)");
}
}
}
I'm interested in learning sockets and have been pouring over SO questions and MSDN docs for two days but cannot figure out why it's not working as I intend. I feel a bit silly even submitting a question because I'm sure it's something basic I'm not understanding. Could someone please drop some knowledge on me?
SOLUTION
//Server
using (TcpClient client = listener.AcceptTcpClient())
{
NetworkStream ns = client.GetStream();
StreamReader sr = new StreamReader(ns);
string message = "";
while (true)
{
message = sr.ReadLine();
Console.WriteLine(message);
}
}
//Client
using (TcpClient client = new TcpClient(hostname, port))
{
if (client.Connected)
{
Console.WriteLine("Connected to server");
NetworkStream ns = client.GetStream();
StreamWriter sw = new StreamWriter(ns) {Autoflush = true};
string message = "";
while (true)
{
message = Console.ReadLine();
sw.WriteLine(message);
}
}
}
If you debug your server, you'll see that it does receive data. You're just not displaying the data, because the only output your server does is after the loop when the byte count returned is 0: Console.WriteLine($"Message:{ dataReceived }\n");. The byte count will only be 0 when the underlying socket has been shutdown. That never happens because your client is stuck in an infinite loop.
A better approach, for a simple text-based client/server example like this, is to use StreamWriter and StreamReader with line-based messages, i.e. WriteLine() and ReadLine(). Then the line breaks serve as the message delimited, and your server can write the message each time it receives a new line.
Note also that in your example above, you are assuming that each chunk of data contains only complete characters. But you're using UTF8 where characters can be two or more bytes, and TCP doesn't guarantee how bytes that are sent are grouped. Using StreamWriter and StreamReader will fix this bug too, but if you wanted to do it explicitly yourself, you can use the Decoder class, which will buffer partial characters.
For some examples of how to correctly implement a simple client/server network program like that, see posts like these:
.NET Simple chat server example
C# multithreading chat server, handle disconnect
C# TcpClient: Send serialized objects using separators?
I have written a TCPClient program to run on my PC. It first initiates a TCP listener to listen on a specific port then reads/writes from/to multiple TCP clients on multiple threads.
I am able to read from the client but whenever I try to send data to it, the program displays that it has sent the data, but the client does not receive anything.
Here's the code:
TcpClient client = listener.AcceptTcpClient();
var childSocketThread = new Thread(() =>
{
if (client.Connected)
{
using (NetworkStream stream = client.GetStream())
{
Console.WriteLine("connected");
byte[] data = new byte[1000];
try
{
if (stream.CanRead)
{
stream.Read(data, 0, 1000);
string dataStr = Encoding.ASCII.GetString(data);
string dataa = dataStr.TrimEnd('\0');
//Console.WriteLine(dataa);
if (dataa.Length > 10)
{
deviceid = ParseRequest(dataa);
byte[] sendnow = Encoding.ASCII.GetBytes(reply[deviceid]);
Array.Clear(data, 0, 1000);
Console.WriteLine("Recieved data: " + dataa);
Console.WriteLine("Sending data");
using (StreamWriter writer = new StreamWriter(stream))
{
writer.AutoFlush = true;
writer.WriteLine(reply[deviceid]);
}
Console.WriteLine(reply[deviceid]);
Console.WriteLine("Sent");
}
Console.WriteLine();
}
}
catch (Exception es)
{
Console.WriteLine(es);
}
}
}
});
childSocketThread.Start();
The server device that I am using is a PLC. Also, things I have already tried:
1) sending directly using Socket.Send method.
2) sending directly using NetworkStream method.
3) accepting the TCP connection as sockets. (Socket device = listener.AcceptSocket).
None of these methods seem to send to the device, even though the program tells me that it had no issues sending data since it displays "Sent" after attempting to send data.
I downloaded another program from this link http://www.codeproject.com/Articles/488668/Csharp-TCP-Server. The test app they provide with it is able to send and receive data on the same port as my program running on the same PC.
I haven't been able to get any direction on how to diagnose and more importantly solve this issue. Any ideas?
Update 2015-08-10 11:18 a.m.:
Output of the Program is as follows:
Update 2015-08-10 11:32 a.m.:
Output of Syslog Console:
Update 2015-08-10 12:07 p.m.:
Output of Wireshark:
We need you to post both sides code. Nevertheless, here is some code that works just fine, you can use it to see if you are doing something wrong.
http://www.codeproject.com/Articles/1415/Introduction-to-TCP-client-server-in-C
I am developing an application for ticketing, client checks for a trip and sends via networkstream to the server, then it will return to the client if that trip was found or not, ex: if trip was not found, it shows in the client trip not found, but then if I choose another trip location, and click again on the checktrip button, the client stops working.
Here below, code of check trip in the client:
try
{
NetworkStream ns = client.GetStream();
StreamWriter sw = new StreamWriter(ns);
StreamReader sr = new StreamReader(ns);
sw.WriteLine(comboBox1.Text);
sw.WriteLine(comboBox2.Text);
sw.WriteLine(dateTimePicker1.Text);
sw.WriteLine(dateTimePicker2.Text);
sw.Flush();
ns.Flush();
string x = sr.ReadLine();//freeze point trying abother reservation.
//MessageBox.Show("Value of x = "+x);
if (x.Equals("yes"))
{
MessageBox.Show("Trip Found");
proceedBtn.Enabled = true;
}
else
{
MessageBox.Show("Trip Not Found\nPlease Try another");
}
}
Do you close your streams? What exact error do you encounter?
//your try block ends here...
catch(Exception ex){MessageBox.Show(ex.Message);}
finally
{
sr.Close(); sw.Close(); ns.Close();
}
EDIT: If you close your streams, you should re-create your TcpClient object and Connect again. Or if you don't want to do this, don't close the streams, the connection should be kept alive
I am working on Passenger information system PIS(Train).So trains send their location to my server PIS using socket on port 8080 .So i should get their locations and show them to passengers . The message that comes from the trains has a template that i should follow that. As you can see here :
So as you can see here we have 6 variables .every integer is 4 byte. The first variable is(4 byte) message source and etc.
In my server i have to detect these variable but i don't know how can i detect them from the message .
static void Listeners()
{
Socket socketForClient = tcpListener.AcceptSocket();
if (socketForClient.Connected)
{
Console.WriteLine("Client:" + socketForClient.RemoteEndPoint + " now connected to server.");
NetworkStream networkStream = new NetworkStream(socketForClient);
System.IO.StreamWriter streamWriter =
new System.IO.StreamWriter(networkStream);
System.IO.StreamReader streamReader =
new System.IO.StreamReader(networkStream);
while (true)
{
TimeTableRepository objTimeTableRepository = new TimeTableRepository();
SensorRepository objSensorRepository = new SensorRepository();
ArrivalTimeRepository objArrivalTimeRepository=new ArrivalTimeRepository();
TrainRepository objTrainRepository = new TrainRepository();
// OnlineTrainRepository ObjOnlineTrainrepository = new OnlineTrainRepository();
//-----
string theString = streamReader.ReadLine();
}
}
}
Here is my listener to port 8080 and theString is the message that is send by trains.My problem is how can i detect this parameters (Message source,message destination and etc) from theString?I mean i need the value of them to store in database .
best regards
Looks like you don't need to detect anything and definitely should not be slapping this in a string to try and parse.
You already know you are getting a bunch of integers back. You even know what order they are in. Use a BinaryReader to get you your numbers and proceed from there. Once you load your reader up, it should be as simple as calling BinaryReader.ReadInt32() to read the message's numbers one after another.
I must also highly recommend you to look into using statements for your streams.
using (var reader = new BinaryReader(networkStream))
{
var messageSource = reader.ReadInt32();
var messageDestination = reader.ReadInt32();
... and so on ...
}
i want to create some service that will run as simple process and will give some other application the possibility to send him xml stream.
What i mean is to create simple process ( exe ) with Infinite loop - and any application will be able to send XML ( file / stream ) to this process => and this process will send the xml to some socket.
Is it possible to do it without pipe ?
I want to do something like COM - that can 'catch' instance of working process.
sure.
you can use Named Pipe classes in c# :
Server :
using (var s = new NamedPipeServerStream ("myPipe"))
{
s.WaitForConnection();
s.WriteByte (100);
Console.WriteLine (s.ReadByte());
}
client code:
using (var s = new NamedPipeClientStream ("myPipe"))
{
s.Connect();
Console.WriteLine (s.ReadByte());
s.WriteByte (200);
}
edit
you can do it by file. + systemfileWatcher Class
put a file in a folder.
the other process will audit this folder.
and now you can transfer info.
edit2
you can use memoryMappedFile
and open a view in each process to see the same mempry region - and transfer data.
I think its the best.
Process A :
static void Main(string[] args)
{
using (MemoryMappedFile mmf = MemoryMappedFile.CreateNew("testmap", 4000))
{
bool mutexCreated;
Mutex mutex = new Mutex(true, "testmapmutex", out mutexCreated);
using (MemoryMappedViewStream stream = mmf.CreateViewStream())
{
BinaryWriter writer = new BinaryWriter(stream);
string st = "Hellow";
int stringSize = Encoding.UTF8.GetByteCount(st); //6
writer.Write(st);
writer.Write(123); //6+4 bytes = 10 bytes
}
mutex.ReleaseMutex();
Console.WriteLine("Start Process B and press ENTER to continue.");
Console.ReadLine();
mutex.WaitOne();
using (MemoryMappedViewStream stream = mmf.CreateViewStream())
{
BinaryReader reader = new BinaryReader(stream);
Console.WriteLine("Process A says: {0}", reader.ReadString());
Console.WriteLine("Process A says: {0}", reader.ReadInt32());
Console.WriteLine("Process B says: {0}", reader.ReadInt32());
}
mutex.ReleaseMutex();
}
}
Process B writes to its region
static void Main(string[] args)
{
try
{
using (MemoryMappedFile mmf = MemoryMappedFile.OpenExisting("testmap"))
{
Mutex mutex = Mutex.OpenExisting("testmapmutex");
mutex.WaitOne();
using (MemoryMappedViewStream stream = mmf.CreateViewStream(11, 0)) // From the 11 byte....
{
BinaryWriter writer = new BinaryWriter(stream, Encoding.UTF8);
writer.Write(2);
}
mutex.ReleaseMutex();
}
}
catch (FileNotFoundException)
{
Console.WriteLine("Memory-mapped file does not exist. Run Process A first.");
}
}
Just use C# Sockets that listen for connections from the other process and write a custom XML file receiver.
Yes, of course you can use a TCP socket connection .If you want to avoid network connection as enlightened in a comment you can use a shared memory approach, for example with Memory-Mapped Files .
What you are looking for is some form of IPC (Inter-process communuication). There's a huge number of possibilities:
Regular file. Windows provides location specifically for temp files (%TEMP%)
For small data, you could use registry, although in most cases it's not a proper use
Memory-mapped file, it's similar to file but in RAM
As Royi properly mentioned, NamedPipeStream is a way to go if you decide to give pipes a try
You could create a WCF endpoint. It sounds like a drag, but Visual Studio will create you all the scaffolding, so it's not such an issue in the end
Window messages could be used if you are developing forms application, and sometimes even if not
You mentioned that the data is XML, so this methodology is not for you, but I'll mention it anyway: you could use named kernel objects, such as: mutexes, events, semaphores to pass signals from one program to another.