title: Expression Language to get formatted datestamp in oozie synchronous dataset definition
body: <p>In my data processing scenario I have some source data paths that have "YY" year format:</p>
  
  <p>/user/${user.name}/${YEAR}/${MONTH}/${DAY}/some dataset name_YY</p>
  
  <p>I know it's a bad design to have 'YY' in the end while YEAR is already present in the path but it's what it's in our current systems and we can't afford to change it for a while.</p>
  
  <pre><code>&lt;datasets&gt;
      &lt;dataset name="hourlyds" frequency="${ds_frequency}"
          initial-instance="${ds_initial_instance}" timezone="${ds_timezone}"&gt;
  
          &lt;uri-template&gt;${baseFsURI}/${YEAR}/${MONTH}/${DAY}/alpha_${coord:formatTime(coord:actualTime(),'yy')}&lt;/uri-template&gt;
          OR (tried one at a time)
          &lt;uri-template&gt;${baseFsURI}/${YEAR}/${MONTH}/${DAY}/alpha_${coord:formatTime(coord:nominalTime(),'yy')}&lt;/uri-template&gt;
  
          &lt;done-flag&gt;${doneFlag}&lt;/done-flag&gt;
      &lt;/dataset&gt;
  &lt;/datasets&gt;
  </code></pre>
  
  <p>None of the 2 ELs worked. Even one non-nested EL expression without any data name prefix failed:</p>
  
  <pre><code>&lt;uri-template&gt;${baseFsURI}/${YEAR}/${MONTH}/${DAY}/${coord:nominalTime()}&lt;/uri-template&gt;
  </code></pre>
  
  <p>Every time it throws following error:</p>
  
  <pre><code>Error: E1004: Expression language evaluation error [Unable to evaluate :${baseFsURI}/${YEAR}/${MONTH}/${DAY}/${coord:nominalTime()}: ], java.lang.Exception: Unable to evaluate :${baseFsURI}/${YEAR}/${MONTH}/${DAY}/${coord:nominalTime()}:
  </code></pre>
  
  <p>How do I get this 'YY' format in datasets?
  Any way other than EL to get it there?</p>
  
  <p>thanks in advance,</p>
  
  <p>rahul</p>