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/****************************************************************************
**
** Copyright (C) 2012 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the QtMobility Components.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
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** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Digia gives you certain additional
** rights. These rights are described in the Digia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
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** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
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** $QT_END_LICENSE$
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****************************************************************************/
/*!
\example btchat
\title Bluetooth Chat Example
The Bluetooth Chat example shows how to use the Qt Connectivity Bluetooth API to communicate
with another application on a remote device using Bluetooth.
\image btchat-example.png
The Bluetooth Chat example implements a simple chat program between multiple parties. The
application always acts as both a server and a client eliminating the need to determine who
should connect to whom.
\section1 Chat Server
The chat server is implemented by the ChatServer class. The ChatServer class is declared as:
\snippet examples/btchat/chatserver.h declaration
The first thing the chat server needs to do is create an instance of QRfcommServer to listen
for incoming Bluetooth connections. Our clientConnected() slot will be called whenever a new
connection is created.
\snippet examples/btchat/chatserver.cpp Create the server
The chat server is only useful if others know that it is there. To enable other devices to
discover it a record describing the service needs to be published in the systems SDP (Service
Discovery Protocol) database. The QBluetoothServiceInfo class encapsulates a service record.
We will publish a service record that contains some textural descriptions of the services, a
UUID that uniquely identifies the service, the discoverability attribute and connection
parameters.
The textural description of the service is stored in the ServiceName, ServiceDescription and
ServiceProvider attributes.
\snippet examples/btchat/chatserver.cpp Service name, description and provider
Bluetooth uses UUIDs as unique identifiers. Our chat service is uses a randomly generated
UUID.
\snippet examples/btchat/chatserver.cpp Service UUID
\snippet examples/btchat/chatserver.cpp Service UUID set
A Bluetooth service is only discoverable if it is in the PublicBrowseGroup.
\snippet examples/btchat/chatserver.cpp Service Discoverability
The ProtocolDescriptorList attribute is used to publish the connection parameters that the
remote device requires to connect to our service. Here we specify that the Rfcomm protocol is
used and set the port number to port that our rfcommServer instance is listening to.
\snippet examples/btchat/chatserver.cpp Protocol descriptor list
Finally we register the service record with the system.
\snippet examples/btchat/chatserver.cpp Register service
As mentioned earlier incoming connections are handled in the clientConnected() slot. In this
slot we get a pointer a QBluetoothSocket representing the next pending connection connect up
slots to the readyRead() and disconnected() signals and emit a signal to notify others that a
new client has connected.
\snippet examples/btchat/chatserver.cpp clientConnected
The readSocket() slot is called whenever data is ready to be read from a client socket. The
slot reads individual lines from the socket converts them from UTF-8 and emits the
messageReceived() signal.
\snippet examples/btchat/chatserver.cpp readSocket
The clientDisconnected() slot is called whenever a client disconnects from the service. The
slot emits a signal to notify others that a client has disconnected and deletes the socket.
\snippet examples/btchat/chatserver.cpp clientDisconnected
The sendMessage() slot is used to send a message to all connected clients. The message is
converted into UTF-8 and appended with a newline before being sent to all clients.
\snippet examples/btchat/chatserver.cpp sendMessage
When the chat server is stop the service record is removed from the system SDP database, all
connected client sockets are deleted and the QRfcommServer instance is deleted.
\snippet examples/btchat/chatserver.cpp stopServer
\section1 Chat Client
The chat client is implemented by the ChatClient class. The ChatClient class is declared as:
\snippet examples/btchat/chatclient.h declaration
The client creates a new QBluetoothSocket and connects to the remote service described by the
\i remoteService parameter. Slots are connected to the sockets readyRead(), connected() and
disconnected() signals.
\snippet examples/btchat/chatclient.cpp startClient
On sucessfull socket connection we emit a signal to notify other.
\snippet examples/btchat/chatclient.cpp connected
Similarily to the chat server the readSocket() slot is called when data is available from the
socket. Lines are read individually and converted from UTF-8. The messageReceived() signal
is emitted.
\snippet examples/btchat/chatclient.cpp readSocket
The sendMessage() slot is used to send a message to the remote device. The message is
converted to UTF-8 and a newline appended.
\snippet examples/btchat/chatclient.cpp sendMessage
To disconnect from the remote chat service the QBluetoothSocket instance is deleted.
\snippet examples/btchat/chatclient.cpp stopClient
\section1 Chat Dialog
The main window of this example is the chat dialog, implemented in the Chat class. This class
displays a chat session between a single ChatServer and zero or more ChatClients. The Chat
class is declared as:
\snippet examples/btchat/chat.h declaration
First we construct the user interface
\snippet examples/btchat/chat.cpp Construct UI
We create an instance of the ChatServer and respond to its clientConnected(),
clientDiconnected() and messageReceived() signals.
\snippet examples/btchat/chat.cpp Create Chat Server
In response to the clientConnected() and clientDisconnected() signals of the ChatServer we
display the typical "foo has joined chat." and "foo has left." messages in the chat session.
\snippet examples/btchat/chat.cpp clientConnected clientDisconnected
Incoming messages from clients connected to the ChatServer are handled in the showMessage()
slot. The message text tagged with the remote device name is displayed in the chat session.
\snippet examples/btchat/chat.cpp showMessage
In response to the connect button being clicked the application starts service discovery and
presents a list of discovered chat services on remote devices. A ChatClient for the service
selected by the user.
\snippet examples/btchat/chat.cpp Connect to remote service
In reponse to connected() signals from ChatClient we display the a "Joined chat with foo."
message in the chat session.
\snippet examples/btchat/chat.cpp connected
Messages are sent to all remote devices via the ChatServer and ChatClient instances by emitting
the sendMessage() signal.
\snippet examples/btchat/chat.cpp sendClicked
We need to clean up ChatClient instances when the remote device forces a disconnect.
\snippet examples/btchat/chat.cpp clientDisconnected
*/
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