title: Why can't I instantiate DataImportHandler in Solr on JBoss?
body: <p>I'm trying to set up Solr 3.5.0 on JBoss 5.1. Everything works quite fine. I copied war into deploy dir, all the dependencies from dist and contrib directories into the lib (or earlier deploy) directory.</p>
  
  <p>I can start a server, everything works fine, but whenever I want to activate the DataImportHandler to index data in my DB, I get an error. </p>
  
  <p>Basically what I do is I copy  is I copy a core from example/example-DIH/solr/db (Or whole example, that doesn't matter), I register the core in solr.xml and at startup I get an error:</p>
  
  <pre><code>15:17:10,707 SEVERE [RequestHandlers] org.apache.solr.common.SolrException: Error Instantiating Request Handler, org.apache.solr.handler.dataimport.DataImportHandler is not a org.apache.solr.request.SolrRequestHandler
  at org.apache.solr.core.SolrCore.createInstance(SolrCore.java:427)
  at org.apache.solr.core.SolrCore.createRequestHandler(SolrCore.java:461)
  at org.apache.solr.core.RequestHandlers.initHandlersFromConfig(RequestHandlers.java:157)
  </code></pre>
  
  <p>I'm pretty sure my request handler definition is correct, but just to be sure:</p>
  
  <pre><code>&lt;requestHandler name="/dataimport" class="org.apache.solr.handler.dataimport.DataImportHandler"&gt;
  &lt;lst name="defaults"&gt;
    &lt;str name="config"&gt;dataimport.xml&lt;/str&gt;
  &lt;/lst&gt;
  </code></pre>
  
  <p></p>
  
  <p>As far as I can find, this error may be caused by DataImportHandler and SolrRequestHandler supposedly being hold different class loaders. </p>
  
  <p>Whenever I start a Solr from the start.jar app in example (I think it starts a Jetty server) it works fine.</p>
  
  <p>My question is: is this really because of the class loader issue, or some other thing? And, more importantly: how do I fix it?</p>