  <section id="upgrading">
    <title>Upgrading from mod_dtcl or NeoWebScript</title>
    <para>
      Rivet is a break from the past, in that we, the authors, have
      attempted to take what we like best about our past efforts, and
      leave out or change things we no longer care for.  Backwards
      compatibility was not a primary goal when creating Rivet, but we
      do provide this information which may be of use to those wishing
      to upgrade from mod_dtcl or NWS installations.
    </para>
    <section>
      <title>mod_dtcl</title>
      <para>
	Rivet was originally based on the dtcl code, but it has
	changed (improved!) quite a bit.  The concepts remain the
	same, but many of the commands have changed.
      </para>
    </section>
    <section>
      <title>NeoWebScript</title>
      <para>
      	NWS was a server-side scripting environment based on the Apache
        HTTP server and Safe-Tcl and it's not maintained anymore.      
      </para>
      <para>
      	The biggest difference between Rivet and Neowebscript is that 
      	Neowebscript was designed for shared hosting while Rivet is more oriented 
      	toward a site that owns all of its content. In the words of Karl Lehenbauer,
      	NWS author and Rivet Team member:
      	</para> 
      	<para>
      	Rivet, however, is considerably more efficient, powerful, and 
      	evolved, though it still can support multiple independent sites on a single 
      	machine through its <quote>separate virtual interpreters</quote> mechanism.
      	<itemizedlist>
      		<listitem>By powerful, the difference is that the full power of Tcl is available 
      		to webpage authors, not the restricted version that NWS provides. 
      		For instance, you can read or write any file in the system that you 
      		have permission to, require any package, open sockets and pipes, etc.</listitem>
      		<listitem>By efficient, the difference is that Tcl interpreters survive past 
      		the generation of a webpage and are reused again and again, reducing the 
      		overhead of generating a page.
      		</listitem>
				<listitem>By evolved, all of our efforts have gone toward Rivet for many 
				years and so, you know, Rivet does more out of the box than Neowebscript did.</listitem>
			</itemizedlist>
      </para>
    </section>
  </section>

