About that compact web server

It’s funny to notice how, subconsciously, the way things work in Grace turn out to look eerily similar to how they work in Python. I was reminded of that fact again when I read this article, illustrating a 15 line web server implementation in Python. This is how it would look in Grace:


#include <grace/daemon.h>
#include <grace/httpd.h>


class myApp : public daemon
{
public:
   myApp (void) : daemon ("myapp") {}
   ~myApp (void) {}
   int main (void);
};


class helloPage : public serverpage
{
public:
   helloPage (httpd &p) : serverpage (p, "/foo") {}
   ~helloPage (void) {}
   
   int execute (value &env, value &argv,
                string &out, value &outhdr)
   {
       if (! argv.exists ("target"))
           argv["target"] = "world";


       out = "Hello, %[target]s\n" %format (argv);
       return 200;
   }
};


$application (myApp);
$version (1.0);


int myApp::main (void)
{
   httpd srv (8180);
   value event;
   new helloPage (srv);
   daemonize ();
   srv.start ();
   while (event.type() != "shutdown")
       event = waitevent ();
   httpd.shutdown ();
   return 0;
}

Admittedly this is a bit more than 15 lines (even if we don’t count lines with curly brackets). We do get a little bit more oomph for those lines, though:

• The application checks a pid-file in /var/run or ${HOME}/var/run.
• The application is forked to the background
• The application responds sanely to SIGTERM

Having an easily extendible web server built into your framework turns out to be pretty convenient: It’s a very quick way to deploy a remotely accessible service.