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<html>
<head>
  <title>AOLserver's Native Services</title>
</head>
<body bgcolor="white">
<table width="100%">
  <tr>
    <td align="left"><h2>AOLserver's Native Services</h2></td>
    <td align="right"><a href="slide-14.html">Prev</a> | <a href="slide-16.html">Next</a></td>
  </tr>
</table>
<hr>

<blockquote>

  I've already mentioned some of the advantages of AOLserver.  While
  the integration with TCL, the pleasures of a good database
  interface, and it's threading have all been mentioned AOLserver has
  even more wonderful qualities.<br/><br/>

  <b>Templating:</b> Separation of data, business logic, and
  presentation is very important to maintaining the sanity of any
  developer.  While the database helps to abstract away data-storage
  the availability of a good templating facility helps to separate
  business logic and presentation.  AOLserver's built-in ADP system is
  a start, but is definitely far from perfect.  It allows individuals
  to insert TCL code inside of what is otherwise a normal HTML
  document.  This is ok in situations like this:

  <pre>
  &lt;head&gt;
    &lt;title&gt;&lt;%=$title%&gt;&lt;/title&gt;
  &lt;/head&gt;</pre>

  but in situations like this:

  <pre>
  &lt;table&gt;
    &lt;% foreach item $items {
          puts "&lt;tr&gt;\n"
          puts "  &lt;td align=\"right\"&gt;[lindex $item 0]&lt;/td&gt;&lt;td&gt;[lindex $item 1]&lt;/td&gt;&lt;td&gt;[lindex $item 2]&lt;/td&gt;\n"
          puts "&lt;/tr&gt;\n"

       }

    %&gt;
  &lt;/table&gt;</pre>

  you may find that your average HTML monkey runs for the hills.<br/><br/>

  <b>One URL to One File:</b> One of my favorite things about OpenACS
  is the idea that one URL maps to one file (pretty much).  This is
  not the case with servlets, or Zope.  In servlets any number of
  different URL's will map to the same servlet, and in Zope each URL
  represents some object in their Object Database, or the method of
  some Python Object.  When a user requests:

  <pre>GET /bboard/forum-view?oid=1245</pre>

  This will typically mean run a script at
  "$ROOT/www/bboard/forum-view".  This makes things easy to debug and
  usually prevents you from having truly enormous files.<br/><br/>
 
  <b>Filters:</b> Now that I've just discussed why I like "One URL to
  One File", I'll totally contradict myself by discussing filters.
  Filters allow an action to be taken before a request occurs.  If you:

  <pre>ns_register_filter do_something /*.jpg</pre>

  do_something will be run whenever you request a .jpg file.  This
  allows you to do authentication, session tracking, etc.  Filters
  return a message like FILTER_OK, FILTER_BREAK, FILTER_RETURN which
  cause effects from allowing other filters to run, to ending the
  request, to carrying on as if nothing has happened.  Filters are
  sometimes dangerous as they violate the Unix principle of least
  surprise.  They can act invisibly and introduce new unforseen
  problems, but they are also a useful tool to quickly add
  functionality to an entire site, or to a particular module.<br/><br/>

  <b>Connection API:</b> One of the things we like our webservers to
  do is protect us from the particulars of HTTP.  AOLserver provides
  the "ns_conn" api which allows developers to get information about
  the HTTP request without having to parse it out themselves.<br/><br/>

  There are other nice AOLserver services, including a plugin
  architecture that allows you to add lots of new modules for handling
  things like XML, SSL and XSLT.  It is easily extensible in C, and
  since it's configuration files are written in TCL you can script
  most of your configuration options.

</blockquote>

<hr>
<a href="tristancohen@yahoo.com">tristancohen@yahoo.com</a>
</body>
</html>
by admin — last modified 2003-04-28 10:18
 

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