QLocalSocket è veramente usato per namedpipes

Question

Secondo la documentazione Qt se vogliamo usare named pipe su Windows, possiamo usare QLocalSocket. Sto scrivendo un server e un programma client con Qt. Se provo a utilizzare l'API WIN32 per scrivere un messaggio nella pipe line, il client Qt non lo mostra. Inoltre, se il client scrive nuovamente utilizzando l'API WIN32, il server Qt non fa eco al messaggio inviato. QLocalSocket è davvero raccomandato per le pipe denominate?

Questo è il codice Win32 Server

 wcout << "Creating an instance of a named pipe..." << endl; 
    // Create a pipe to send data 
    HANDLE pipe = CreateNamedPipeW(
     L"\\\\.\\pipe\\ServicePipe", // name of the pipe 
     PIPE_ACCESS_OUTBOUND, // 1-way pipe -- send only 
     PIPE_TYPE_BYTE, // send data as a byte stream 
     100, // only allow 1 instance of this pipe 
     0, // no outbound buffer 
     0, // no inbound buffer 
     0, // use default wait time 
     NULL // use default security attributes 
     ); 

    if (pipe == NULL || pipe == INVALID_HANDLE_VALUE) { 
     wcout << "Failed to create outbound pipe instance."; 
     // look up error code here using GetLastError() 
     system("pause"); 
     return 1; 
    } 

    wcout << "Waiting for a client to connect to the pipe..." << endl; 

    // This call blocks until a client process connects to the pipe 
    BOOL result = ConnectNamedPipe(pipe, NULL); 
    if (!result) { 
     wcout << "Failed to make connection on named pipe." << endl; 
     // look up error code here using GetLastError() 
     CloseHandle(pipe); // close the pipe 
     system("pause"); 
     return 1; 
    } 

    wcout << "Sending data to pipe..." << endl; 

    // This call blocks until a client process reads all the data 
    wcout <<endl<<"Input your message: "; 

    wstring data=L""; 
    getline(wcin,data); 
    DWORD numBytesWritten = 0; 
    result = WriteFile(
     pipe, // handle to our outbound pipe 
     data.c_str(), // data to send 
     wcslen(data.c_str()) * sizeof(wchar_t), // length of data to send (bytes) 
     &numBytesWritten, // will store actual amount of data sent 
     NULL // not using overlapped IO 
     ); 


    if (result) { 
     wcout << "Number of bytes sent: " << numBytesWritten << endl; 
    } else { 
     wcout << "Failed to send data." << endl; 
     // look up error code here using GetLastError() 
    } 

    // Close the pipe (automatically disconnects client too) 
    CloseHandle(pipe); 

    wcout << "Done." << endl; 

Questo è il lato client Win32:

wcout << "Connecting to pipe..." << endl; 
    // Open the named pipe 
    // Most of these parameters aren't very relevant for pipes. 
    HANDLE pipe = CreateFileW(
     L"\\\\.\\pipe\\ServicePipe", 
     GENERIC_READ, // only need read access 
     FILE_SHARE_READ | FILE_SHARE_WRITE, 
     NULL, 
     OPEN_EXISTING, 
     FILE_ATTRIBUTE_NORMAL, 
     NULL 
     ); 

    if (pipe == INVALID_HANDLE_VALUE) { 
     wcout << "Failed to connect to pipe." << endl; 
     // look up error code here using GetLastError() 
     system("pause"); 
     return 1; 
    } 

    wcout << "Reading data from pipe..." << endl; 

    // The read operation will block until there is data to read 
    wchar_t buffer[128]; 
    DWORD numBytesRead = 0; 
    BOOL result = ReadFile(
     pipe, 
     buffer, // the data from the pipe will be put here 
     127 * sizeof(wchar_t), // number of bytes allocated 
     &numBytesRead, // this will store number of bytes actually read 
     NULL // not using overlapped IO 
     ); 

    if (result) { 
     buffer[numBytesRead/sizeof(wchar_t)] = '?'; // null terminate the string 
     wcout << "Number of bytes read: " << numBytesRead << endl; 
     wcout << "Message: " << buffer << endl; 
    } else { 
     wcout << "Failed to read data from the pipe." << endl; 
    } 

    // Close our pipe handle 
    CloseHandle(pipe); 

    wcout << "Done." << endl; 

Questo è il lato Qt Server

LocalSocketIpcServer::LocalSocketIpcServer(QString servername, QObject *parent) 
:QObject(parent) { 
m_server = new QLocalServer(this); 
if (!m_server->listen(servername)) { 
    showMessage("Not able to start the Server"); 
} 

connect(m_server, SIGNAL(newConnection()), this, SLOT(socket_new_connection())); 
} 

LocalSocketIpcServer::~LocalSocketIpcServer() { 

} 


void LocalSocketIpcServer::socket_new_connection() { 

QLocalSocket *clientConnection = m_server->nextPendingConnection(); 

while (clientConnection->bytesAvailable() < (int)sizeof(quint32)) 
    clientConnection->waitForReadyRead(); 



//connect(clientConnection,SIGNAL(readyRead()),clientConnection,SLOT(rea)); 
connect(clientConnection, SIGNAL(disconnected()),clientConnection, SLOT(deleteLater())); 

QDataStream in(clientConnection); 
in.setVersion(QDataStream::Qt_5_1); 
if (clientConnection->bytesAvailable() < (int)sizeof(quint16)) { 
    return; 
} 

QString message; 
in >> message; 

QByteArray block; 
QDataStream out(&block, QIODevice::WriteOnly); 
QString msg=+"Message recieved with content "+message+"\n"; 
out.setVersion(QDataStream::Qt_5_1); 
out <<msg; 
out.device()->seek(0); 
clientConnection->write(block); 
clientConnection->flush(); 
clientConnection->disconnectFromServer(); 

emit messageReceived(message); 
} 


void LocalSocketIpcServer::showMessage(QString msg) 
{ 
QMessageBox m; 
m.setText(msg); 
m.exec(); 
} 
LocalSocketIpcServer::FrmMain(QWidget *parent) :QMainWindow(parent),ui(new Ui::FrmMain) 
{ 
ui->setupUi(this); 

m_server = new LocalSocketIpcServer("\\\\.\\pipe\ServicePipe", this); 
connect(m_server, SIGNAL(messageReceived(QString)), this, SLOT(messageReceived(QString))); 
} 

LocalSocketIpcServer::~FrmMain() 
{ 
delete ui; 
} 

void LocalSocketIpcServer::messageReceived(QString message) 
{ 
    ui->textBrowser->append(message+"\n"); 
} 

Questo è il lato client Qt

LocalSocketIpcClient::LocalSocketIpcClient(QString remoteServername, QObject *parent) : 
    QObject(parent) { 

m_socket = new QLocalSocket(this); 
m_serverName = remoteServername; 

connect(m_socket, SIGNAL(connected()), this, SLOT(socket_connected())); 
connect(m_socket, SIGNAL(disconnected()), this, SLOT(socket_disconnected())); 

connect(m_socket, SIGNAL(readyRead()), this, SLOT(socket_readReady())); 
connect(m_socket, SIGNAL(error(QLocalSocket::LocalSocketError)), 
     this, SLOT(socket_error(QLocalSocket::LocalSocketError))); 
} 

LocalSocketIpcClient::~LocalSocketIpcClient() { 
m_socket->abort(); 
delete m_socket; 
m_socket = NULL; 
} 

QString LocalSocketIpcClient::Read() 
{ 

QDataStream in(this->m_socket); 
in.setVersion(QDataStream::Qt_5_1); 

if (m_socket->bytesAvailable() < (int)sizeof(quint16)) { 
    return "No data available"; 
} 

QString message; 
in >> message; 
return message; 
} 

void LocalSocketIpcClient::send_MessageToServer(QString message) { 
m_socket->abort(); 
m_message = message; 
m_socket->connectToServer(m_serverName,QIODevice::ReadWrite); 
} 


void LocalSocketIpcClient::socket_connected(){ 
QByteArray block; 
QDataStream out(&block, QIODevice::ReadWrite); 
out.setVersion(QDataStream::Qt_5_1); 
out << m_message; 
out.device()->seek(0); 
m_socket->write(block); 
m_socket->flush(); 
} 

void LocalSocketIpcClient::socket_disconnected() { 
//showMessage("Client socket_disconnected"); 
} 


void LocalSocketIpcClient::socket_readReady() { 
//showMessage("Client socket read Ready"); 

QDataStream in(this->m_socket); 
in.setVersion(QDataStream::Qt_5_1); 

if (m_socket->bytesAvailable() < (int)sizeof(quint16)) { 
    return; 
} 

QString message; 
in >> message; 
emit RecievedDataFromServer(message); 

} 

void LocalSocketIpcClient::socket_error(QLocalSocket::LocalSocketError e) { 
/* 
QString errorMessage="Client socket_error:"; 

switch (e) { 
case QLocalSocket::ConnectionRefusedError: 
    errorMessage+="The connection was refused by the peer (or timed out)."; 
    break; 

case QLocalSocket::PeerClosedError: 
    errorMessage+="The remote socket closed the connection. Note that the client socket (i.e., this socket) will be closed after the remote close notification has been sent."; 
    break; 

case QLocalSocket::ServerNotFoundError: 
    errorMessage+="The local socket name was not found."; 
    break; 

case QLocalSocket::SocketAccessError: 
    errorMessage+="The socket operation failed because the application lacked the required privileges."; 
    break; 

case QLocalSocket::SocketResourceError: 
    errorMessage+="The local system ran out of resources (e.g., too many sockets)."; 
    break; 

case QLocalSocket::SocketTimeoutError: 
    errorMessage+="The socket operation timed out."; 
    break; 

case QLocalSocket::DatagramTooLargeError: 
    errorMessage+="The datagram was larger than the operating system's limit (which can be as low as 8192 bytes)."; 
    break; 

case QLocalSocket::ConnectionError: 
    errorMessage+="An error occurred with the connection."; 
    break; 

case QLocalSocket::UnsupportedSocketOperationError: 
    errorMessage+="The requested socket operation is not supported by the local operating  system."; 
    break; 

case QLocalSocket::UnknownSocketError: 
    errorMessage+="An unidentified error occurred."; 
    break; 

default: 
    break; 
} 
showMessage(errorMessage); 
*/ 
} 

void LocalSocketIpcClient::showMessage(QString msg) 
{ 
QMessageBox m; 
m.setText(msg); 
m.exec(); 
} 
LocalSocketIpcClient::SingleMessageSend(QWidget *parent) : 
QDialog(parent), 
ui(new Ui::SingleMessageSend) 
{ 
ui->setupUi(this); 

client = new LocalSocketIpcClient("\\\\.\\pipe\ServicePipe", this); 
connect(this->client,SIGNAL(RecievedDataFromServer(QString)),this,SLOT(UpdateGUI(QString))); 
} 

LocalSocketIpcClient::~SingleMessageSend() 
{ 
delete ui; 
} 

void SingleMessageSend::on_pushButton_clicked() 
{ 
QString msg=this->ui->lineEdit->text().trimmed(); 
client->send_MessageToServer(msg); 

} 

void SingleMessageSend::UpdateGUI(QString message) 
{ 
ui->textEdit->insertPlainText(message+"\n"); 
} 

void SingleMessageSend::on_pushButton_2_clicked() 
{ 
ui->textEdit->insertPlainText(client->Read()+QString("\n")); 
} 

Answer 1

Senza passare attraverso tutto il codice, posso rispondere affermativamente. Ecco un po 'di codice da un'applicazione di lavoro che scrive da un'applicazione Qt ad un tubo chiamato in un'altra applicazione Qt (ripristina un'altra applicazione che viene ridotto al minimo):

QLocalSocket ls; 
ls.connectToServer("Restore Server", QIODevice::WriteOnly); 
if (!ls.waitForConnected(5000)) 
{ 
     qDebug(ls.errorString().toUtf8()); 
     return false; 
} 
ls.write("raise"); 
if (!ls.waitForBytesWritten(5000)) 
{ 
     qDebug(ls.errorString().toUtf8()); 
     return false; 
} 
ls.disconnectFromServer(); 

L'applicazione da ristrutturare set le cose così:

localServer = new QLocalServer(this); 

connect(localServer, SIGNAL(newConnection()), this, 
    SLOT(messageFromOtherInstance())); 
localServer->listen("Restore Server"); 

Quando arriva il momento di leggere il messaggio, lo faccio in questo modo:

QLocalSocket *localSocket = localServer->nextPendingConnection(); 
if (!localSocket->waitForReadyRead(5000)) 
{ 
     qDebug(localSocket->errorString().toLatin1()); 
     return; 
} 
QByteArray byteArray = localSocket->readAll(); 
QString message = QString::fromUtf8(byteArray.constData()); 

if (message == "raise") 
    bringToTop(this); 

può ben essere che Qt named pipe e M $ named pipe sono in qualche modo incompatibili. Suggerisco di scrivere un'app M $ framework per scrivere sul client M $ framework e un'app M $ framework da leggere, per accertarmi che funzionino entrambi correttamente. Quindi, sostituire l'app Qt per leggere dal server Qt. Se ciò non funziona, si tratta di una sorta di incompatibilità del framework (anche se mi aspetto che entrambi interagiscano correttamente con il sistema operativo). Una cosa di cui essere sicuri in situazioni come questa è assicurarsi che i processi non blocchino. Ecco perché, ad es. Mi assicuro che la lettura sia pronta prima di leggerla. Potresti anche dover lavare il tubo dopo aver scritto sul lato M $, anche se non l'ho fatto con Qt.

(Si noti che da allora ho scoperto che se è aperta una finestra di dialogo Stampa, Anteprima di stampa, Imposta pagina o Sfoglia per file, interrompe il ciclo del messaggio Qt e l'app non risponde ai messaggi come questo. La finestra di dialogo dei caratteri, OTOH, non blocca l'app padre. Vai figura.)