[Work on ch23
John Goerzen <jgoerzen@complete.org>**20080213001506] {
hunk ./en/ch23-webclient.xml 4
-  <title>Web client programming</title>
+  <title>Extended Example: Web Client Programming</title>
+  <para>
+    By this point, you've seen how to interact with a database, parse
+    things, and handle errors.  Let's now take this a step farther and
+    introduce a web client library to the mix.
+  </para>
+  <para>
+    We'll develop a real application in this chapter: a podcast
+    downloader, or "podcatcher".  The idea of a podcatcher is simple.
+    It is given a list of URLs to process.  Each URL provides an XML
+    file in the RSS format.  Inside this XML file, we'll find
+    references to URLs for audio files to download.
+  </para>
+  <para>
+    Podcatchers usually let the user subscribe to podcasts by adding
+    RSS URLs to their configuration.  Then, the user can periodically
+    run an update operation.  The podcatcher will download the RSS
+    documents, examine them for audio file references, and download
+    any audio files that haven't already been downloaded on behalf of
+    this user.
+  </para>
+  <tip>
+    <para>Users often call the RSS document a podcast or the
+    podcast feed, and each individual audio file an episode.
+    </para>
+  </tip>
+  <para>
+    To make this happen, we need to have several things:
+  </para>
+  <itemizedlist>
+    <listitem><para>An HTTP client library to download files</para>
+    </listitem>
+    <listitem><para>An XML parser</para>
+    </listitem>
+    <listitem><para>A way to specify and persistently store 
+        which podcasts we're interested in</para>
+    </listitem>
+    <listitem><para>A way to persistently store which podcast episodes
+    we've already downloaded
+      </para>
+    </listitem>
+  </itemizedlist>
hunk ./en/ch23-webclient.xml 47
-  <remark>FIXME</remark>
+  <para>
+    The last two items can be accomodated via a database we'll set up
+    using HDBC.  The first two can be accomodated via other library
+    modules we'll introduce in this chapter.
+  </para>
+
+  <tip>
+    <para>The code in this chapter was written specifically for this
+    book, but is based off code written for hpodder, an existing
+    podcatcher written in Haskell.  hpodder has many more features
+    than the examples presented here, which make it too long and
+    complex for coverage in this book.  If you are interested in
+    studying hpodder, its source code is freely available at <ulink
+    url="http://software.complete.org/hpodder"/>.
+    </para>
+  </tip>
+    
}