Desenvolver uma aplicação que precisa de comunicar com a rede não precisa ser complicado. Neste webinar será mostrado como o Qt torna programação para rede muito mais simples. Será dado um rápido overview de como criar sockets UDP e TCP, broadcast e multicast além de fazer requisições REST usando somente a API do QtNetwork.

1. ECOSYSTEM
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2. QtNetwork explained
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3. TÓPICOS
• Introdução ao QtNetwork
• Por que usar QtNetwork
• Sockets
●
QAbstractSocket
●
QTcpSocket
– QsslSocket
●
QTcpServer
●
QudpSocket
– Broadcast
– Multicast (somente 4.8 !symbian)
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4. TÓPICOS
• High level networking
●
QnetworkAccessManager
●
QnetworkConfiguration
●
QnetworkConfigurationManager
●
QnetworkSession
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QnetworkRequest
●
QNetworkReply
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5. Introdução ao QtNetwork
• QtNetwork é um módulo do Qt
• Provê uma interface cross platforma para escrever aplicações
cliente servidor TCP/IP
• Suporta proxy
• Possui classes para realizar requests http e ftp, acessar web
services e tratar suas respostas.
• Pegar informações sobre dispositivos de rede
• É possível ainda gerenciar o estado de conexão com a rede, ter
configurações específicas para cada uma e realizar ações.

6. Por que usar QtNetwork?
int main()
{
int main()
int fd = socket(AF_INET, SOCK_STREAM, 0); {
if (fd == 1)
{ QCoreApplication app(argc, argv);
printf("can not create socket");
exit(1);
} QTcpServer server;
struct sockaddr_in saddr;
bzero(&saddr, sizeof(saddr));
server.listen(QHostAddress::Any, 1100);
saddr.sin_family = AF_INET;
saddr.sin_port = htons(1100);
saddr.sin_addr.s_addr = htonl(INADDR_ANY);
while (server.waitForNewConnection()) {
do {
if (bind(fd,(struct sockaddr *)&saddr, sizeof(saddr)) == 1)
{ QTcpSocket *socket = server.nextPendingConnection();
printf("error bind failed"); socket->write(“Hello, world!”);
exit(1);
} socket->disconnectFromHost();
if (listen(fd, 10) == 1)
socket->waitForDisconnected();
{ delete socket;
printf("error listen failed");
exit(1);
} while (server.hasPendingConnections());
} }
for(;;) {
int connfd = accept(fd, NULL, NULL); }
if(connfd <= 0) {
printf("error accept failed");
exit(1);
}
write(connfd, "Hello world!n", 13);
close(connfd);
}
return 0;
}

7. Sockets: QAbstractSocket
• QabstractSocket é uma camada de abstração multi
plataforma para api nativa de network
• Implementa TCP, UDP e sockets locais
• Herda de QIODevice
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8. Sockets: QTcpSocket
●
Subclasse de conveniência do QAbstractSocket
●
Pode ser utilizado pra implementar vários tipos
protocolos
●
Stream de dados contínuo
●
Poder ser usado de maneira asíncrona ou síncrona.

9. Sockets: QTcpSocket
ClientSocket::ClientSocket(QObject *parent)
ServerSocket::ServerSocket(QObject *parent) : QTcpSocket(parent)
: QTcpSocket(parent) {
{ connect(this, SIGNAL(readyRead()),
connect(this, SIGNAL(readyRead()),
this, SLOT(onReadyRead()));
this, SLOT(onReadyRead()));
}
connect(this, SIGNAL(disconnected()),
void ServerSocket::onServerInfoResponse(const QVariantMap &map) this, SLOT(onDisconnected()));
{
QJson::Serializer serializer; connect(this, SIGNAL(error(QAbstractSocket::SocketError)),
this, SLOT(onError(QAbstractSocket::SocketError)));
write(serializer.serialize(map));
}
flush();
} void ClientSocket::onDisconnected()
{
void ServerSocket::onServerStatusChanged(const QString &status) qDebug() << "[ClientSocket] Client disconnected!";
}
{
QVariantMap map;
void ClientSocket::onError(QAbstractSocket::SocketError error)
map["what"] = "server";
{
map["action"] = "statusChanged";
map["status"] = status; qDebug() << "[ClientSocket] Error: " << error;
}
QJson::Serializer serializer;
write(serializer.serialize(map)); void ClientSocket::requestServerInfo()
flush(); {
} QVariantMap map;
QJson::Serializer serializer;
void ServerSocket::onReadyRead()
{
while (canReadLine()) { map["what"] = "server";
QByteArray line = readLine(); map["action"] = "serverInfo";
write(serializer.serialize(map)");
bool parserOk = true; }
QJson::Parser parser;
void ClientSocket::onQJsonParsingFinished(const QVariant &json, bool ok, const QString &error_msg)
QVariant var = parser.parse(line, &parserOk);
{
if (!parserOk) { if (!ok) {
qWarning() qWarning() << Q_FUNC_INFO << "json error at" << error_msg;
<< Q_FUNC_INFO return;
<< "json error at" }
<< parser.errorLine()
<< parser.errorString(); QVariantMap map = json.toMap();
} else {
QString what = map["what"].toString();
QVariantMap map = var.toMap();
if (what == "server") {
QString what = map["what"].toString();
if (what == "server") { QString action = map["action"].toString();
QString action = map["action"].toString(); if (action == "serverInfo") {
if (action == "info") { emit serverInfoReceived(map);
emit serverInfoRequested(); }
} }
}
}
}
}
}

10. Sockets: QTcpServer
●
Precisa receber conexões? Essa é a classe certa.
●
Pode ser single threaded or multi threaded
●
Single threaded
●
Um ou vários sockets usando mesmo Event loop
●
Ou Bloqueante
●
Multi threaded
●
Um socket por thread
– Bloqueante
– Ou um Event loop por thread

11. Sockets: QTcpServer
Server::Server(QObject *parent)
: QtcpServer(parent)
, m_serverInfo()
{
}
void Server::start()
{
listen(QHostAddress::Any, 12345);
}
void Server::incomingConnection(int socketDescriptor)
{
ServerSocket *sock = new ServerSocket;
sock->setSocketDescriptor(socketDescriptor);
QThread *thread = new QThread;
sock->moveToThread(thread);
connect(sock, SIGNAL(disconnected()),
sock, SLOT(deleteLater()));
connect(sock, SIGNAL(destroyed()),
thread, SLOT(quit()));
connect(thread, SIGNAL(finished()),
thread, SLOT(deleteLater()));
connect(this, SIGNAL(statusChanged(const Qstring &)),
sock, SLOT(onServerStatusChanged(const Qstring &)));
connect(sock, SIGNAL(serverInfoRequested()),
this, SLOT(onServerInfoRequested()));
thread->start();
}
void Server::onServerInfoRequested()
{
ServerSocket *sock = qobject_cast<ServerSocket*>(sender());
if (!sock)
return;
QMetaObject::invokeMethod(sock, "onServerInfoResponse",
Q_ARG(QVariantMap, m_serverInfo));
}

12. Sockets: QudpSocket Broadcast
BroadcastAnnounce::BroadcastAnnounce(QObject *parent)
: QObject(parent)
, m_socket(new QUdpSocket(this))
, m_timer(new QTimer(this))
, m_serverInfo()
{
connect(m_timer, SIGNAL(timeout()), this, SLOT(sendDatagram()));
}
void BroadcastAnnounce::start()
{
if (m_timer->isActive())
m_timer->stop();
m_timer->start(1000);
}
void BroadcastAnnounce::stop()
{
m_timer->stop();
}
void BroadcastAnnounce::setServerInfo(const QVariantMap &map)
{
m_serverInfo = map;
}
void BroadcastAnnounce::sendDatagram()
{
QByteArray datagram;
QDataStream out(&datagram, QIODevice::WriteOnly);
out.setVersion(QDataStream::Qt_4_7);
out << QVariant(m_serverInfo);
m_socket->writeDatagram(datagram.data(), datagram.size(), QHostAddress::Broadcast,
UDP_PORT);
}

13. Sockets: QudpSocket Broadcast
BroadcastAnnounce::BroadcastAnnounce(QObject *parent) BroadcastDiscover::BroadcastDiscover(QObject *parent)
: QObject(parent)
: QObject(parent) , m_socket()
, m_timer(new QTimer(this))
, m_socket(new QUdpSocket(this))
{
, m_timer(new QTimer(this)) connect(m_timer, SIGNAL(timeout()), this, SLOT(stop()));
}
, m_serverInfo()
{ void BroadcastDiscover::start()
{
connect(m_timer, SIGNAL(timeout()), this, SLOT(sendDatagram()));
m_socket = new QUdpSocket(this);
} m_socket->bind(UDP_PORT, QUdpSocket::ShareAddress);
connect(m_socket, SIGNAL(readyRead()),
this, SLOT(processDatagrams()));
void BroadcastAnnounce::start() m_timer->start(10000);
}
{
if (m_timer->isActive()) void BroadcastDiscover::stop()
{
m_timer->stop(); disconnect(m_socket, SIGNAL(readyRead()),
this, SLOT(processDatagrams()));
m_socket->close();
m_timer->start(1000); emit timeout();
} }
void BroadcastDiscover::processDatagrams()
void BroadcastAnnounce::stop() {
QUdpSocket *socket = qobject_cast<QUdpSocket *>(sender());
{ if (!socket)
m_timer->stop(); return;
} while (socket->hasPendingDatagrams()) {
QByteArray datagram;
void BroadcastAnnounce::setServerInfo(const QVariantMap &map)
QHostAddress host;
{
datagram.resize(socket->pendingDatagramSize());
m_serverInfo = map;
socket->readDatagram(datagram.data(), datagram.size(), &host);
}
QVariant message;
void BroadcastAnnounce::sendDatagram()
QDataStream dataStream(&datagram, QIODevice::ReadOnly);
{ dataStream >> message;
QByteArray datagram;
const QVariantMap map = message.toMap();
QDataStream out(&datagram, QIODevice::WriteOnly); if (map["app_id"].toString() == APP_ID) {
const QString action = map["action"].toString();
out.setVersion(QDataStream::Qt_4_7); if (action == "serverAnnounce") {
out << QVariant(m_serverInfo); emit serverFound(map);
}
m_socket->writeDatagram(datagram.data(), datagram.size(), QHostAddress::Broadcast, }
UDP_PORT); }
} }

14. Sockets: QudpSocket Multicast
MulticastAnnounce::MulticastAnnounce(QObject *parent) MulticastDiscover::MulticastDiscover(QObject *parent)
: QObject(parent)
: QObject(parent) , m_socket()
, m_socket(new QUdpSocket(this)) , m_timer(new QTimer(this))
{
, m_timer(new QTimer(this))
connect(m_timer, SIGNAL(timeout()), this, SLOT(stop()));
, m_serverInfo() }
{
void MulticastDiscover::start()
connect(m_timer, SIGNAL(timeout()), this, SLOT(sendDatagram()));
{
m_socket = new QUdpSocket(this);
m_socket->setSocketOption(QAbstractSocket::MulticastTtlOption, 1); m_socket->bind(UDP_PORT, QUdpSocket::ShareAddress);
m_socket->joinMulticastGroup(QHostAddress("239.255.43.21"));
}
connect(m_socket, SIGNAL(readyRead()),
this, SLOT(processDatagrams()));
void MulticastAnnounce::start()
m_timer->start(10000);
{ }
if (m_timer->isActive())
void MulticastDiscover::stop()
m_timer->stop(); {
disconnect(m_socket, SIGNAL(readyRead()),
this, SLOT(processDatagrams()));
m_timer->start(1000);
m_socket->close();
} emit timeout();
}
void MulticastAnnounce::stop()
void MulticastDiscover::processDatagrams()
{ {
m_timer->stop(); QUdpSocket *socket = qobject_cast<QUdpSocket *>(sender());
if (!socket)
} return;
while (socket->hasPendingDatagrams()) {
void MulticastAnnounce::setServerInfo(const QVariantMap &map)
QByteArray datagram;
{ QHostAddress host;
m_serverInfo = map;
datagram.resize(socket->pendingDatagramSize());
}
socket->readDatagram(datagram.data(), datagram.size(), &host);
void MulticastAnnounce::sendDatagram() QVariant message;
QDataStream dataStream(&datagram, QIODevice::ReadOnly);
dataStream >> message;
{
QByteArray datagram; const QVariantMap map = message.toMap();
if (map["app_id"].toString() == APP_ID) {
QDataStream out(&datagram, QIODevice::WriteOnly);
const QString action = map["action"].toString();
out.setVersion(QDataStream::Qt_4_8); if (action == "serverAnnounce") {
out << QVariant(m_serverInfo); emit serverFound(map);
}
}
m_socket->writeDatagram(datagram.data(), datagram.size(), QHostAddress("239.255.43.21"), UDP_PORT); }
}
}

15. Sockets: QUdpSocket
●
Subclasse de conveniência do QabstractSocket para
UDP
●
Envio de pacotes de dados ao invés de stream
contínuo
●
Possui suporte a Broadcast
●
Desde o Qt 4.8 suporte a Multicast

16. QnetworkConfigurationManager
1- Definir o Ponto de Acesso
QNetworkConfigurationManager manager;
//Define que o usuário pode escolher um ponto de acesso
const bool canStartIAP = (manager.capabilities()&
QnetworkConfigurationManager::CanStartAndStopInterfaces);
//Retorna a configuração padrão atual
manager.defaultConfiguration();
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17. QnetworkConfiguration
1- Definir o Ponto de Acesso
QNetworkConfigurationManager manager;
//Define que o usuário pode escolher um ponto de acesso
const bool canStartIAP = (manager.capabilities()&
QNetworkConfigurationManager::CanStartAndStopInterfaces);
//Se existe um ponto de acesso padrao. Basta utiliza-lo usando
a configuracao padrao do QNetWorkConfigurarionManager
QNetworkConfiguration cfg = manager.defaultConfiguration();
if (!cfg.isValid() || !canStartIAP) {
// Pontos de acesso nao encontrados ou impossivel se
conectar
// Alertar usuario e fazer tratamento de erro
return;
}
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18. QnetworkSession
// Caso a conexao tenha ocorrido com sucesso, abrir um
QNetworkSession usando a configuracao padrao
m_session = new QNetworkSession(cfg);
//Conectar sinais necessarios
connect(m_session, SIGNAL(closed()), this, SLOT(closed()));
connect(m_session,
SIGNAL(stateChanged(QNetworkSession::State)), this,
SLOT(stateChanged(QNetworkSession::State)));
connect(m_session,
SIGNAL(error(QNetworkSession::SessionError)), this,
SLOT(error(QNetworkSession::SessionError)));
Abrir aconexao
m_session->open();
// Espera a sessão ser aberta e continua a partir dai
m_session->waitForOpened();
Para fechar a sessão, usar o slot finished()
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19. QnetworkAccessManager
1- Criar um Network Access Manager
nam = new QNetworkAccessManager(this);
2- Conectar o sinal finished a um slot para tratar o resultado
QObject::connect(nam, SIGNAL(finished(QNetworkReply*)),
this, SLOT(finishedSlot(QNetworkReply*)));
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20. QnetworkRequest
1- Criar um Network Access Manager
nam = new QNetworkAccessManager(this);
2- Conectar o sinal finished a um slot para tratar o resultado
QObject::connect(nam, SIGNAL(finished(QNetworkReply*)),
this, SLOT(finishedSlot(QNetworkReply*)));
3- Criar o Request
QUrl url(http://query.yahooapis.com/v1/public/yql);
url.addQueryItem(QUERY_PARAM,
QLatin1String("select+*+from+geo.placefinder+where+text="")
+ "Sao Paulo" + QLatin1String("""));
url.addQueryItem("format", "json");
QnetworkRequest request(url);
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21. QNetworkReply
1- Criar um Network Access Manager
nam = new QNetworkAccessManager(this);
2- Conectar o sinal finished a um slot para tratar o resultado
QObject::connect(nam, SIGNAL(finished(QNetworkReply*)),
this, SLOT(finishedSlot(QNetworkReply*)));
3- Criar o Request
QUrl url(http://query.yahooapis.com/v1/public/yql);
url.addQueryItem(QUERY_PARAM,
QLatin1String("select+*+from+geo.placefinder+where+text="")
+ "Sao Paulo" + QLatin1String("""));
url.addQueryItem("format", "json");
QnetworkRequest request(url);
4- Guardar o reply do request par ser usado como identificador da resposta
QNetworkReply* reply = nam->get(request)
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22. QNetworkReply
4- Tratar o Reply
void MyHttpEngine::finishedSlot(QNetworkReply* reply) {
// Ler Atributos do Repply como ocodigo de Status HTTP
QVariant statusCodeV = reply->attribute(QNetworkRequest::HttpStatusCodeAttribute);
void MyHttpEngine::finishedSlot(QNetworkReply* reply) {
// Ler Atributos do Repply como o codigo de Status HTTP
QVariant statusCodeV = reply->attribute(QNetworkRequest::HttpStatusCodeAttribute);
// Ou a URL, se esta tiver sido redirecionada:
QVariant redirectionTargetUrl = reply->attribute(QNetworkRequest::RedirectionTargetAttribute);
// Verificar se houve erro
if (reply->error() == QnetworkReply::NoError) {
// Se nao houve erro, ler os dados da resposta
//Ex1: Criando um QImage da resposta
QImageReader imageReader(reply);
QImage pic = imageReader.read();
}
}
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23. Canais de comunicação
• @nokiadev_brasil
• rodrigo.belem@openbossa.org
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