title: DSS boxcarring and request_box
body: <p>I am facing a problem in DSS boxcarring.</p>
  <p>I enabled boxcarring in DSS and wrote queries for selecting data from three tables separately and inserting them in another three tables. When I try using it and click on <code>begin_boxcar</code> then my three operations and then <code>end_boxcar</code> it works well. An operation (<code>request_boxcar</code>) is created automatically and contains my three operations in order. When I click on it on try it, it works and my operations was run but when I use task schedule and select <code>request_box</code> I encounter an error. I use it with my endpoint in my browser but it doesn't work. How can I fix that?</p>
  <pre><code>http://IP:Port/services/Test/request_box
  </code></pre>
  <p>This is the error I encountered:</p>
  <pre><code> type Exception report message description The server encountered an
   internal error that prevented it from fulfilling this request.
   exception org.apache.axis2.AxisFault
      org.apache.axis2.AxisFault.makeFault(AxisFault.java:430)
      org.wso2.carbon.core.transports.CarbonServlet.doGet(CarbonServlet.java:155)
      javax.servlet.http.HttpServlet.service(HttpServlet.java:620)
      javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
      org.eclipse.equinox.http.servlet.internal.ServletRegistration.service(ServletRegistration.java:61)
      org.eclipse.equinox.http.servlet.internal.ProxyServlet.processAlias(ProxyServlet.java:128)
      org.eclipse.equinox.http.servlet.internal.ProxyServlet.service(ProxyServlet.java:68)
      javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
      org.wso2.carbon.tomcat.ext.servlet.DelegationServlet.service(DelegationServlet.java:68)
      org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
      org.wso2.carbon.ui.filters.CSRFPreventionFilter.doFilter(CSRFPreventionFilter.java:88)
      org.wso2.carbon.ui.filters.CRLFPreventionFilter.doFilter(CRLFPreventionFilter.java:59)
      org.wso2.carbon.tomcat.ext.filter.CharacterSetFilter.doFilter(CharacterSetFilter.java:61)
   root cause java.lang.NullPointerException
      org.apache.axis2.builder.BuilderUtil.buildsoapMessage(BuilderUtil.java:148)
      org.apache.axis2.builder.XFormURLEncodedBuilder.processDocument(XFormURLEncodedBuilder.java:118)
      org.apache.axis2.transport.TransportUtils.createDocumentElement(TransportUtils.java:188)
      org.apache.axis2.transport.TransportUtils.createSOAPMessage(TransportUtils.java:146)
      org.apache.axis2.transport.http.util.RESTUtil.processURLRequest(RESTUtil.java:116)
      org.apache.axis2.transport.http.AxisServlet$RestRequestProcessor.processURLRequest(AxisServlet.java:843)
      org.wso2.carbon.core.transports.CarbonServlet.handleRestRequest(CarbonServlet.java:303)
      org.wso2.carbon.core.transports.CarbonServlet.doGet(CarbonServlet.java:152)
      javax.servlet.http.HttpServlet.service(HttpServlet.java:620)
      javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
      org.eclipse.equinox.http.servlet.internal.ServletRegistration.service(ServletRegistration.java:61)
      org.eclipse.equinox.http.servlet.internal.ProxyServlet.processAlias(ProxyServlet.java:128)
      org.eclipse.equinox.http.servlet.internal.ProxyServlet.service(ProxyServlet.java:68)
      javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
      org.wso2.carbon.tomcat.ext.servlet.DelegationServlet.service(DelegationServlet.java:68)
      org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
      org.wso2.carbon.ui.filters.CSRFPreventionFilter.doFilter(CSRFPreventionFilter.java:88)
      org.wso2.carbon.ui.filters.CRLFPreventionFilter.doFilter(CRLFPreventionFilter.java:59)
      org.wso2.carbon.tomcat.ext.filter.CharacterSetFilter.doFilter(CharacterSetFilter.java:61)
   note The full stack trace of the root cause is available in the Apache
   Tomcat/7.0.59 logs.
  </code></pre>