Turn Google Site pages into RSS feed

gistfile1.js

/*   
   Copyright 2011 Martin Hawksey

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
*/

/*
Uses the new ContentServices to generate a RSS feed from a set of Google Site pages. 

To use install then  Publish > Deploy as web app.  You'll need to use the olds style 
service url https://script.google.com/macros/exec?service={service_key}&siteurl={url
encode_Google_Sites_url&page={page_stub} 

e.g. https://script.google.com/macros/exec?service={service_key_removed}&siteurl=htt
ps%3A%2F%2Fsites.google.com%2Fsite%2Fscriptsexamples%2F&page=custom-methods

To make available to aggregators like Google Reader the service needs to allow 
anonymous access

*/


function doGet(e) {
  var siteUrl = decodeURIComponent(e.parameter.siteurl);
  var page = decodeURIComponent(e.parameter.page);
  var cache = CacheService.getPrivateCache();// using Cache service to prevent too many urlfetch 
  var cached = cache.get(siteUrl+page);
  if (cached != null) { // if value in cache return it
    var feed = cached;
  } else {
    var feed = turnSitesPageIntoRSS(siteUrl,page);
    try {
      cache.put(siteUrl+page, feed, 21600);// cache for 1/4 day
    } catch (e) {
      
    }
  }
  return ContentService.createTextOutput(feed).setMimeType(ContentService.MimeType.RSS);
}

function turnSitesPageIntoRSS(siteUrl, page){
  //var siteUrl = 'https://sites.google.com/site/scriptsexamples/';
  //var page = 'custom-methods'; 
  var output = "";
  var site = SitesApp.getSiteByUrl(siteUrl);
  var topPage = SitesApp.getPageByUrl(siteUrl+page);
  
  var rssHead = '<?xml version="1.0" encoding="UTF-8" ?> '+
                '  <rss version="2.0"><channel>'+
                '   <title>'+site.getTitle()+': '+topPage.getTitle()+'</title>' +
                '   <description>'+site.getSummary()+'</description>'+
                '   <link>'+siteUrl+page+'</link>';
  var rssFoot = '  </channel></rss>';
  var items = "";
  
  output = rssHead;
  
  var pages = topPage.getAllDescendants();
  for (i in pages){
    items =  '<item>'+
              '<title>'+pages[i].getTitle()+'</title>'+
              '<link>'+pages[i].getUrl()+'</link>'+
              '<description><![CDATA['+pages[i].getHtmlContent()+']]></description>'+
              '<pubDate>'+Utilities.formatDate(pages[i].getLastUpdated(), 'GMT', 'EEE, d MMM yy HH:mm:ss z') +'</pubDate>'+
              '</item>';
    output += items;
  }
  output += rssFoot;
  return output;
}