title: Add/Remove/update entry between two xml file either using Ant xmltask or using perl scripting
body: <p>Here is first xml file input.xml,</p>
  
  <p><strong>input.xml</strong>:</p>
  
  <pre><code>&lt;Mapping&gt;
          &lt;Common&gt;
              &lt;Apps&gt;
                  &lt;App ID = "id1"&gt;
                  &lt;config key = "Format" value = "PDF"/&gt;
                  &lt;/App&gt;
                  &lt;App ID = "id2"&gt;
                  &lt;config key = "Logging" value = "no"/&gt;
                  &lt;config key = "ExtraLogging" value = "no"/&gt;
                  &lt;/App&gt;
              &lt;/Apps&gt;
  
              &lt;All&gt;
              &lt;config key="log1" value="N"/&gt;
              &lt;/All&gt;
          &lt;/Common&gt;
  &lt;/Mapping&gt;
  </code></pre>
  
  <p>Need to read from input.xml and Add/Remove/update respective entry in output.xml.</p>
  
  <p><strong>output.xml:</strong></p>
  
  <pre><code>    &lt;Mapping&gt;
              &lt;Common&gt;
                  &lt;Apps&gt;
                      &lt;App ID = "id1"&gt;
                      &lt;config key = "Format" value = "DOC"/&gt;
                      &lt;/App&gt;
                      &lt;App ID = "id2"&gt;
                      &lt;config key = "Logging" value = "yes"/&gt;
                      &lt;/App&gt;
                  &lt;/Apps&gt;
  
                  &lt;All&gt;
                  &lt;config key="log1" value="N"/&gt;
                  &lt;/All&gt;
              &lt;/Common&gt;
      &lt;/Mapping&gt;
  </code></pre>