code: protected SiteResourceBundle getBundle (int siteId)
          throws IOException
      {
          // look up the site resource bundle for this site
          SiteResourceBundle bundle = _bundles.get(siteId);
  
          // if we haven't got one, create one
          if (bundle == null) {
              // obtain the string identifier for this site
              String ident = _siteIdent.getSiteString(siteId);
              // compose that with the jar file directory to obtain the
              // path to the site-specific jar file
              File file = new File(_jarPath, ident + JAR_EXTENSION);
              // create a handle for this site-specific jar file
              bundle = new SiteResourceBundle(file);
              // cache our new bundle
              _bundles.put(siteId, bundle);
          }
  
          return bundle;
      }
docs: Obtains the site-specific jar file for the specified site. This
  should only be called when the lock for this site is held.