class SimpleNonPeriodicClient : public RTT::TaskContext
{
protected:
    // DATA INTERFACE
 
    // *** OUTPUTS ***
 
    /// the last read data
    RTT::WriteDataPort<std::string>            lastRead_port;
 
    /// the number of items sucessfully read
    RTT::Attribute<int>                        countRead_attr;
 
    // *** CONFIGURATION ***
 
    // name to listen for incoming connections on, either FQDN or IPv4 addres
    RTT::Property<std::string>                hostName_prop;
    // port to listen on
    RTT::Property<int>                        hostPort_prop;
    // timeout in seconds, when waiting for connection
    RTT::Property<int>                        connectionTimeout_prop;
    // timeout in seconds, when waiting to read
    RTT::Property<int>                        readTimeout_prop;
 
public:
    SimpleNonPeriodicClient(std::string name);
    virtual ~SimpleNonPeriodicClient();
 
protected:
    /// reset count and lastRead, attempt to connect to remote
    virtual bool startHook();
    /// attempt to read and process one packet
    virtual void updateHook();
    /// close the socket and cleanup
    virtual void stopHook();
    /// cause updateHook() to return
    virtual bool breakUpdateHook();
 
    /// Socket used to connect to remote host
    QTcpSocket*    socket;
    /// Flag indicating to updateHook() that we want to quit
    bool        quit;
};

#include "SimpleNonPeriodicClient.hpp"
#include <rtt/Logger.hpp>
#include <ocl/ComponentLoader.hpp>
 
#include <QTcpSocket>

SimpleNonPeriodicClient::SimpleNonPeriodicClient(std::string name) :
        RTT::TaskContext(name),
        lastRead_port("lastRead", ""),
        countRead_attr("countRead", 0),
        hostName_prop("HostName", 
                      "Name to listen for incoming connections on (FQDN or IPv4)", ""),
        hostPort_prop("HostPort", 
                      "Port to listen on (1024-65535 inclusive)", 0),
        connectionTimeout_prop("ConnectionTimeout", 
                               "Timeout in seconds, when waiting for connection", 0),
        readTimeout_prop("ReadTimeout", 
                         "Timeout in seconds, when waiting for read", 0),
        socket(new QTcpSocket), 
        quit(false)
{
    ports()->addPort(&lastRead_port);
 
    attributes()->addAttribute(&countRead_attr);
 
    properties()->addProperty(&hostName_prop);
    properties()->addProperty(&hostPort_prop);
    properties()->addProperty(&connectionTimeout_prop);
    properties()->addProperty(&readTimeout_prop);
}

SimpleNonPeriodicClient::~SimpleNonPeriodicClient()
{
    delete socket;
}

bool SimpleNonPeriodicClient::startHook()
{
    bool        rc                    = false;        // prove otherwise
    std::string    hostName            = hostName_prop.rvalue();
    int            hostPort            = hostPort_prop.rvalue();
    int         connectionTimeout    = connectionTimeout_prop.rvalue();
 
    quit = false;
 
    // attempt to connect to remote host/port
    log(Info) << "Connecting to " << hostName << ":" << hostPort << endlog();
    socket->connectToHost(hostName.c_str(), hostPort);
    if (socket->waitForConnected(1000 * connectionTimeout))    // to millseconds
    {
        log(Info) << "Connected" << endlog();
        rc = true;
    }
    else
    {    
        log(Error) << "Error connecting: " << socket->error() << ", " 
                   << socket->errorString().toStdString() << endlog();
        // as we now return false, this component will fail to start.
    }
 
    return rc;
}

void SimpleNonPeriodicClient::updateHook()
{
    // wait for some data to arrive, timing out if necessary
    int     readTimeout        = readTimeout_prop.rvalue();
    log(Debug) << "Waiting for data with timeout=" << readTimeout << " seconds" << endlog();
    if (!socket->waitForReadyRead(1000 * readTimeout))
    {
        log(Error) << "Error waiting for data: " << socket->error() << ", " 
                   << socket->errorString().toStdString() 
                   << ". Num bytes = " 
                   << socket->bytesAvailable() << endlog();
        log(Error) << "Disconnecting" << endlog();
        // disconnect socket, and do NOT call this function again
        // ie no engine()->getActivity()->trigger()
        socket->disconnectFromHost();
        return;        
    }
 
    // read and print whatever data is available, but stop if instructed
    // to quit
    while (!quit && (0 < socket->bytesAvailable()))
    {
#define    BUFSIZE        10
        char            str[BUFSIZE + 1];    // +1 for terminator
        qint64            numRead;
 
        numRead = socket->read((char*)&str[0], 
                               min(BUFSIZE, socket->bytesAvailable()));
        str[BUFSIZE] = '\0';        // forcibly terminate
        if (0 < numRead)
        {
            log(Info) << "Got " << numRead << " bytes : '" << &str[0] << "'" << endlog();
            countRead_attr.set(countRead_attr.get() + 1);
            lastRead_port.Set(&str[0]);
        }
    }
 
    // if not quitting then trigger another immediate call to this function, to
    // get the next batch of data
    if (!quit)
    {
        engine()->getActivity()->trigger();
    }
}

engine()->getActivity()->trigger();

void SimpleNonPeriodicClient::stopHook()
{
    if (socket->isValid() &&
        (QAbstractSocket::ConnectedState == socket->state()))
    {
        log(Info) << "Disconnecting" << endlog();
        socket->disconnectFromHost();
    }
}

bool SimpleNonPeriodicClient::breakUpdateHook()
{
    quit = true;
    return true;
}

ORO_CREATE_COMPONENT(SimpleNonPeriodicClient)

cd /path/to/SimpleNonPeriodicClient
mkdir build
cd build
cmake .. -DOROCOS_TARGET=macosx
make

nc -l 50001

cd /path/to/SimpleNonPeriodicClient/build
deployer-macosx -s ../SimpleNonPeriodicClient.xml