Como: Usar pipes anônimos para comunicação entre processos locais

  • Artigo

Os pipes anônimos fornecem comunicação entre processos em um computador local. Eles oferecem menos funcionalidades que pipes nomeados, mas também exigem menos sobrecarga. Você pode usar pipes anônimos para facilitar a comunicação entre processos em um computador local. Você não pode usar pipes anônimos para comunicações através de uma rede.

Para implementar pipes anônimos, use as classes AnonymousPipeServerStream e AnonymousPipeClientStream.

Exemplo 1

O exemplo a seguir demonstra uma maneira de enviar uma cadeia de caracteres de um processo pai para um processo filho usando pipes anônimos. Este exemplo cria um objeto AnonymousPipeServerStream em um processo pai com um valor PipeDirection de Out. Em seguida, o processo pai cria um processo filho usando um identificador de cliente para criar um objeto AnonymousPipeClientStream. O processo filho tem um valor PipeDirection de In.

Em seguida, o processo pai envia uma cadeia de caracteres fornecida pelo usuário ao processo filho. A cadeia de caracteres é exibida no console do processo filho.

O exemplo a seguir mostra o processo do servidor.

#using <System.dll>
#using <System.Core.dll>

using namespace System;
using namespace System::IO;
using namespace System::IO::Pipes;
using namespace System::Diagnostics;

ref class PipeServer
{
public:
    static void Main()
    {
        Process^ pipeClient = gcnew Process();

        pipeClient->StartInfo->FileName = "pipeClient.exe";

        AnonymousPipeServerStream^ pipeServer =
            gcnew AnonymousPipeServerStream(PipeDirection::Out,
            HandleInheritability::Inheritable);

        Console::WriteLine("[SERVER] Current TransmissionMode: {0}.",
            pipeServer->TransmissionMode);

        // Pass the client process a handle to the server.
        pipeClient->StartInfo->Arguments =
            pipeServer->GetClientHandleAsString();
        pipeClient->StartInfo->UseShellExecute = false;
        pipeClient->Start();

        pipeServer->DisposeLocalCopyOfClientHandle();

        try
        {
            // Read user input and send that to the client process.
            StreamWriter^ sw = gcnew StreamWriter(pipeServer);

            sw->AutoFlush = true;
            // Send a 'sync message' and wait for client to receive it.
            sw->WriteLine("SYNC");
            pipeServer->WaitForPipeDrain();
            // Send the console input to the client process.
            Console::Write("[SERVER] Enter text: ");
            sw->WriteLine(Console::ReadLine());
            sw->Close();
        }
        // Catch the IOException that is raised if the pipe is broken
        // or disconnected.
        catch (IOException^ e)
        {
            Console::WriteLine("[SERVER] Error: {0}", e->Message);
        }
        pipeServer->Close();
        pipeClient->WaitForExit();
        pipeClient->Close();
        Console::WriteLine("[SERVER] Client quit. Server terminating.");
    }
};

int main()
{
    PipeServer::Main();
}

using System;
using System.IO;
using System.IO.Pipes;
using System.Diagnostics;

class PipeServer
{
    static void Main()
    {
        Process pipeClient = new Process();

        pipeClient.StartInfo.FileName = "pipeClient.exe";

        using (AnonymousPipeServerStream pipeServer =
            new AnonymousPipeServerStream(PipeDirection.Out,
            HandleInheritability.Inheritable))
        {
            Console.WriteLine("[SERVER] Current TransmissionMode: {0}.",
                pipeServer.TransmissionMode);

            // Pass the client process a handle to the server.
            pipeClient.StartInfo.Arguments =
                pipeServer.GetClientHandleAsString();
            pipeClient.StartInfo.UseShellExecute = false;
            pipeClient.Start();

            pipeServer.DisposeLocalCopyOfClientHandle();

            try
            {
                // Read user input and send that to the client process.
                using (StreamWriter sw = new StreamWriter(pipeServer))
                {
                    sw.AutoFlush = true;
                    // Send a 'sync message' and wait for client to receive it.
                    sw.WriteLine("SYNC");
                    pipeServer.WaitForPipeDrain();
                    // Send the console input to the client process.
                    Console.Write("[SERVER] Enter text: ");
                    sw.WriteLine(Console.ReadLine());
                }
            }
            // Catch the IOException that is raised if the pipe is broken
            // or disconnected.
            catch (IOException e)
            {
                Console.WriteLine("[SERVER] Error: {0}", e.Message);
            }
        }

        pipeClient.WaitForExit();
        pipeClient.Close();
        Console.WriteLine("[SERVER] Client quit. Server terminating.");
    }
}

Imports System.IO
Imports System.IO.Pipes
Imports System.Diagnostics

Class PipeServer
    Shared Sub Main()
        Dim pipeClient As New Process()

        pipeClient.StartInfo.FileName = "pipeClient.exe"

        Using pipeServer As New AnonymousPipeServerStream(PipeDirection.Out, _
            HandleInheritability.Inheritable)

            Console.WriteLine("[SERVER] Current TransmissionMode: {0}.",
                pipeServer.TransmissionMode)

            ' Pass the client process a handle to the server.
            pipeClient.StartInfo.Arguments = pipeServer.GetClientHandleAsString()
            pipeClient.StartInfo.UseShellExecute = false
            pipeClient.Start()

            pipeServer.DisposeLocalCopyOfClientHandle()

            Try
                ' Read user input and send that to the client process.
                Using sw As New StreamWriter(pipeServer)
                    sw.AutoFlush = true
                    ' Send a 'sync message' and wait for client to receive it.
                    sw.WriteLine("SYNC")
                    pipeServer.WaitForPipeDrain()
                    ' Send the console input to the client process.
                    Console.Write("[SERVER] Enter text: ")
                    sw.WriteLine(Console.ReadLine())
                End Using
            Catch e As IOException
                ' Catch the IOException that is raised if the pipe is broken
                ' or disconnected.
                Console.WriteLine("[SERVER] Error: {0}", e.Message)
            End Try
        End Using

        pipeClient.WaitForExit()
        pipeClient.Close()
        Console.WriteLine("[SERVER] Client quit. Server terminating.")
    End Sub
End Class

Exemplo 2

O exemplo a seguir mostra o processo do cliente. O processo do servidor inicia o processo do cliente e oferece a ele um identificador de cliente. O executável que resulta do código do cliente deve ser chamado de pipeClient.exe e copiado para o mesmo diretório que o executável do servidor antes que o processo do servidor seja executado.

#using <System.Core.dll>

using namespace System;
using namespace System::IO;
using namespace System::IO::Pipes;

ref class PipeClient
{
public:
    static void Main(array<String^>^ args)
    {
        if (args->Length > 1)
        {
            PipeStream^ pipeClient = gcnew AnonymousPipeClientStream(PipeDirection::In, args[1]);

            Console::WriteLine("[CLIENT] Current TransmissionMode: {0}.",
                pipeClient->TransmissionMode);

            StreamReader^ sr = gcnew StreamReader(pipeClient);

            // Display the read text to the console
            String^ temp;

            // Wait for 'sync message' from the server.
            do
            {
                Console::WriteLine("[CLIENT] Wait for sync...");
                temp = sr->ReadLine();
            }
            while (!temp->StartsWith("SYNC"));

            // Read the server data and echo to the console.
            while ((temp = sr->ReadLine()) != nullptr)
            {
                Console::WriteLine("[CLIENT] Echo: " + temp);
            }
            sr->Close();
            pipeClient->Close();
        }
        Console::Write("[CLIENT] Press Enter to continue...");
        Console::ReadLine();
    }
};

int main()
{
    array<String^>^ args = Environment::GetCommandLineArgs();
    PipeClient::Main(args);
}

using System;
using System.IO;
using System.IO.Pipes;

class PipeClient
{
    static void Main(string[] args)
    {
        if (args.Length > 0)
        {
            using (PipeStream pipeClient =
                new AnonymousPipeClientStream(PipeDirection.In, args[0]))
            {
                Console.WriteLine("[CLIENT] Current TransmissionMode: {0}.",
                   pipeClient.TransmissionMode);

                using (StreamReader sr = new StreamReader(pipeClient))
                {
                    // Display the read text to the console
                    string temp;

                    // Wait for 'sync message' from the server.
                    do
                    {
                        Console.WriteLine("[CLIENT] Wait for sync...");
                        temp = sr.ReadLine();
                    }
                    while (!temp.StartsWith("SYNC"));

                    // Read the server data and echo to the console.
                    while ((temp = sr.ReadLine()) != null)
                    {
                        Console.WriteLine("[CLIENT] Echo: " + temp);
                    }
                }
            }
        }
        Console.Write("[CLIENT] Press Enter to continue...");
        Console.ReadLine();
    }
}

Imports System.IO
Imports System.IO.Pipes

Class PipeClient
    Shared Sub Main(args() as String)
        If args.Length > 0 Then
            Using pipeClient As New AnonymousPipeClientStream(PipeDirection.In, args(0))
                Console.WriteLine("[CLIENT] Current TransmissionMode: {0}.", _
                   pipeClient.TransmissionMode)

                Using sr As New StreamReader(pipeClient)
                    ' Display the read text to the console
                    Dim temp As String

                    ' Wait for 'sync message' from the server.
                    Do
                        Console.WriteLine("[CLIENT] Wait for sync...")
                        temp = sr.ReadLine()
                    Loop While temp.StartsWith("SYNC") = False

                    ' Read the server data and echo to the console.
                    temp = sr.ReadLine()
                    While Not temp = Nothing
                        Console.WriteLine("[CLIENT] Echo: " + temp)
                        temp = sr.ReadLine()
                    End While
                End Using
            End Using
        End If
        Console.Write("[CLIENT] Press Enter to continue...")
        Console.ReadLine()
    End Sub
End Class

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