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<div class="sect1" title="Plugs and Sockets Example">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="sec-plugs-sockets-example"></a>Plugs and Sockets Example</h2></div></div></div>
<p>
The following is a simple example of using sockets and plugs. The method
of communication between processes is deliberately kept very simple: The
<code class="classname">Plug</code> writes its ID out to a text file named
<code class="filename">plug.id</code> and the process with the socket reads the ID
from this files. In a real program, you may want to use a more
sophisticated method of inter-process communication.
</p>
<p><a class="ulink" href="http://git.gnome.org/cgit/gtkmm-documentation/tree/examples/book/socket/" target="_top">Source Code</a></p>
<p>File: <code class="filename">socket.cc</code>
</p>
<pre class="programlisting">
#include <iostream>
#include <fstream>
#include <gtkmm.h>
#include <gtkmm/socket.h>
using namespace std;
const char* id_filename = "plug.id";
void plug_added()
{
cout << "A plug was added" << endl;
}
bool plug_removed()
{
cout << "A Plug was removed" << endl;
return true;
}
class MySocketWindow : public Gtk::Window
{
public:
MySocketWindow()
{
ifstream infile(id_filename);
if (infile)
{
Gtk::Socket* socket = Gtk::manage(new Gtk::Socket());
add(*socket);
socket->signal_plug_added().connect(sigc::ptr_fun(plug_added));
socket->signal_plug_removed().connect(sigc::ptr_fun(plug_removed));
Gdk::NativeWindow plug_id;
infile >> plug_id;
infile.close();
socket->add_id(plug_id);
}
else
{
Gtk::Label* label = Gtk::manage(
new Gtk::Label(
"Plug id file not found.\n Make sure plug is running."));
add(*label);
set_size_request(150, 50);
}
show_all();
}
};
int main(int argc, char** argv)
{
Gtk::Main app(argc, argv);
MySocketWindow win;
app.run(win);
return 0;
}
</pre>
<p>File: <code class="filename">plug.cc</code>
</p>
<pre class="programlisting">
#include <iostream>
#include <fstream>
#include <gtkmm.h>
#include <gtkmm/plug.h>
#include <glib/gstdio.h>
using namespace std;
const char* id_filename = "plug.id";
void on_embed()
{
cout << "I've been embedded." << endl;
}
class MyPlug : public Gtk::Plug
{
public:
MyPlug() :
m_label("I am the plug")
{
set_size_request(150, 100);
add(m_label);
signal_embedded().connect(sigc::ptr_fun(on_embed));
show_all();
}
private:
Gtk::Label m_label;
};
int main(int argc, char** argv)
{
Gtk::Main app(argc, argv);
MyPlug plug;
ofstream out(id_filename);
out << plug.get_id();
out.close();
cout << "The window ID is: " << plug.get_id() << endl;
app.run(plug);
// remove the ID file when the program exits
g_remove(id_filename);
return 0;
}
</pre>
<p>
This example creates two executable programs: <code class="filename">socket</code>
and <code class="filename">plug</code>. The idea is that
<code class="filename">socket</code> has an application window that will embed a
widget from the <code class="filename">plug</code> program. The way this example
is designed, <code class="filename">plug</code> must be running first before
starting <code class="filename">socket</code>. To see the example in action,
execute the following commands in order from within the example directory:
</p>
<p>
Start the <code class="filename">plug</code> program and send it to the background
(or just use a different terminal).
</p>
<pre class="screen">$ ./plug &</pre>
<p>
After which you should see something like the following:
</p>
<pre class="screen">The window ID is: 69206019</pre>
<p>Then start the <code class="filename">socket</code> program:</p>
<pre class="screen">$ ./socket</pre>
<p>
After starting <code class="filename">socket</code>, you should see the following
output in the terminal:
</p>
<pre class="screen">I've been embedded.
A plug was added</pre>
<p>
The first line of output is from <code class="filename">plug</code>, after it has
been notified that it has been embedded inside of a
<code class="classname">Socket</code>. The second line was emitted by
<code class="filename">socket</code> in response to its
<code class="methodname">plug_added</code> signal. If everything was done as
described above, the <code class="filename">socket</code> window should look
roughly like the following:
</p>
<div class="screenshot"><div><img src="figures/socket.png"></div></div>
<p>
If for some reason the <code class="classname">Socket</code> couldn't attach the
<code class="classname">Plug</code>, the window would look something like this:
</p>
<div class="screenshot"><div><img src="figures/socket-fail.png"></div></div>
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