@@TITLE Why Use DGD?@@

<h2>Why Use DGD?</h2>

<p>DGD is a networked server and a language environment. It uses an
object-oriented variant of C called LPC and provides powerful
special-purpose extensions to that language. True to its roots, DGD
is best known as a server for multiplayer networked games called
MUDs. That's where the original LPC language came from, and it's
still a common use of even industrial-strength servers like
DGD.</p>

<p>There are many good reasons to use DGD if you're building a MUD,
and a surprising number even if you're building some other kind of
networked server. Yahoo Chat, for instance, is built on top of DGD.
First, a few bullet points about DGD...</p>

<h3>DGD is an amazing server:</h3>

<ul>
  <li>Because it's <a href=
  "LibWriting/Persistence.html">persistent</a>. That doesn't just
  mean that the game world persists or that you can save and
  restore. For DGD, that means that the LPC objects can be dumped
  to a state file on shutdown and reloaded at startup without
  writing specific object-saving or object-reloading code. Pointers
  and object state are maintained transparently.</li>

  <li>Because it does what's necessary to be persistent, such as
  allowing you to recompile every LPC object in place without
  rebooting, disconnecting users or losing data. You can even do it
  incrementally without stopping what you're doing. New object data
  shows up and old data disappears quietly and transparently.</li>

  <li>Because it's clean and well-designed. Dworkin works hard to
  make DGD the cleanest, most secure LPMUD out there. DGD's LPC
  dialect really shows it. DGD resembles an Operating System or a
  language environment (which it is) much more than a MUD
  server.</li>

  <li>Because Dworkin works hard. New features and bug fixes are
  added all the time to the experimental (but usually very stable)
  versions of DGD. You see stuff that other MUD servers don't have
  and won't have any time soon like atomic functions with full
  rollback.</li>
</ul>

<h3>What Does DGD Do That Other Drivers and Servers Don't?</h3>

<ul>
  <li>The rlimits() structure can be used to limit how much stack
  space and processor time a given function can take. If the time
  or space runs out, the function is interrupted cleanly and
  smoothly without restarting the interpreter.</li>

  <li>DGD is disk-based, so it can store massive datasets without
  massive amounts of RAM. Its swapping is efficient, well tested
  and highly configurable.</li>

  <li>DGD is highly secure and strongly tested in commercial
  products like the Skotos servers and Yahoo Chat (formerly
  iChat).</li>

  <li>Most LPC environments absolutely forbid commercial use. DGD,
  however, can be used commercially if you purchase a license from
  Dworkin or from <a href="Skotos/index.html">Skotos</a>.</li>

  <li>DGD allows precompiled code and server extensions -- for
  thost times when it really has to run at full native speed.</li>

  <li>DGD allows you to recompile absolutely any LPC object on the
  fly and change anything or everything about it. It also has the
  management code and hooks to let you usefully do this. Since DGD
  does far more in LPC than most drivers, this lets you reconfigure
  anything about your game nearly instantly, and run your
  development servers on the same LPC data without an interruption
  for days, months or years.</li>

  <li>DGD allows you to dump all game state in one lump, and reload
  that statedump with a new DGD version. To upgrade DGD, just dump
  state, upgrade the DGD server code and restart. All your objects,
  files and players are exactly where they were. Only your current
  network connections are lost, and absolutely everything about DGD
  can be upgraded this way. You can upgrade your library without
  even that much disruption.</li>

  <li>DGD's dialect of LPC includes a lot of new extensions for
  better typechecking and error checking than most LPC servers. It
  removes several redundant and insecure features (like shadowing
  and hardcoded snooping) that can prevent a library from being
  securable.</li>
</ul>

<h3>And here's more information:</h3>

<ul>
  <li><a href="external/Skotos_Summary.txt">Skotos Tech's (somewhat
  outdated) Summary of what DGD is all about</a></li>

  <li><a href="DGD_Terms.html">A Glossary of DGD Terms and
  Concepts</a></li>

  <li><a href="MudOS_vs_DGD.html">How is MudOS Different from
  DGD?</a></li>

  <li><a href="CSharp_vs_DGD.html">How is C# Different from
  DGD?</a></li>

  <li><a href="Java_vs_DGD.html">How is Java Different from
  DGD?</a></li>
</ul>