public static void writeBPMNDI(BpmnModel model, XMLStreamWriter xtw) throws Exception {
    // BPMN DI information
    xtw.writeStartElement(BPMNDI_PREFIX, ELEMENT_DI_DIAGRAM, BPMNDI_NAMESPACE);

    String processId = null;
    if (model.getPools().size() > 0) {
      processId = "Collaboration";
    } else {
      processId = model.getMainProcess().getId();
    }

    xtw.writeAttribute(ATTRIBUTE_ID, "BPMNDiagram_" + processId);

    xtw.writeStartElement(BPMNDI_PREFIX, ELEMENT_DI_PLANE, BPMNDI_NAMESPACE);
    xtw.writeAttribute(ATTRIBUTE_DI_BPMNELEMENT, processId);
    xtw.writeAttribute(ATTRIBUTE_ID, "BPMNPlane_" + processId);

    // System.out.println("DI EXPORT");
    for (String elementId : model.getLocationMap().keySet()) {

      if (model.getFlowElement(elementId) != null
          || model.getArtifact(elementId) != null
          || model.getPool(elementId) != null
          || model.getLane(elementId) != null) {

        xtw.writeStartElement(BPMNDI_PREFIX, ELEMENT_DI_SHAPE, BPMNDI_NAMESPACE);
        xtw.writeAttribute(ATTRIBUTE_DI_BPMNELEMENT, elementId);
        xtw.writeAttribute(ATTRIBUTE_ID, "BPMNShape_" + elementId);

        GraphicInfo graphicInfo = model.getGraphicInfo(elementId);
        FlowElement flowElement = model.getFlowElement(elementId);
        if (flowElement != null
            && flowElement instanceof SubProcess
            && graphicInfo.getExpanded() != null) {
          xtw.writeAttribute(ATTRIBUTE_DI_IS_EXPANDED, String.valueOf(graphicInfo.getExpanded()));
        }

        if (flowElement == null) {
          boolean foundLane = false;
          for (Pool pool : model.getPools()) {
            if (foundLane) {
              break;
            }
            if (elementId.equals(pool.getId())) {
              if (graphicInfo.getHorizontal() != null) {
                xtw.writeAttribute(
                    ATTRIBUTE_DI_IS_HORIZONTAL, String.valueOf(graphicInfo.getHorizontal()));
              }
            } else {
              Process process = model.getProcess(pool.getId());
              if (process != null) {
                for (Lane lane : process.getLanes()) {
                  if (elementId.equals(lane.getId())) {
                    foundLane = true;
                    if (graphicInfo.getHorizontal() != null) {
                      xtw.writeAttribute(
                          ATTRIBUTE_DI_IS_HORIZONTAL, String.valueOf(graphicInfo.getHorizontal()));
                    }
                    break;
                  }
                }
              }
            }
          }
        }

        xtw.writeStartElement(OMGDC_PREFIX, ELEMENT_DI_BOUNDS, OMGDC_NAMESPACE);
        xtw.writeAttribute(ATTRIBUTE_DI_HEIGHT, "" + graphicInfo.getHeight());
        xtw.writeAttribute(ATTRIBUTE_DI_WIDTH, "" + graphicInfo.getWidth());
        xtw.writeAttribute(ATTRIBUTE_DI_X, "" + graphicInfo.getX());
        xtw.writeAttribute(ATTRIBUTE_DI_Y, "" + graphicInfo.getY());
        xtw.writeEndElement();

        xtw.writeEndElement();
      }
    }

    for (String elementId : model.getFlowLocationMap().keySet()) {

      if (model.getFlowElement(elementId) != null || model.getArtifact(elementId) != null) {

        xtw.writeStartElement(BPMNDI_PREFIX, ELEMENT_DI_EDGE, BPMNDI_NAMESPACE);
        xtw.writeAttribute(ATTRIBUTE_DI_BPMNELEMENT, elementId);
        xtw.writeAttribute(ATTRIBUTE_ID, "BPMNEdge_" + elementId);

        List<GraphicInfo> graphicInfoList = model.getFlowLocationGraphicInfo(elementId);
        for (GraphicInfo graphicInfo : graphicInfoList) {
          xtw.writeStartElement(OMGDI_PREFIX, ELEMENT_DI_WAYPOINT, OMGDI_NAMESPACE);
          xtw.writeAttribute(ATTRIBUTE_DI_X, "" + graphicInfo.getX());
          xtw.writeAttribute(ATTRIBUTE_DI_Y, "" + graphicInfo.getY());
          xtw.writeEndElement();
        }

        GraphicInfo labelGraphicInfo = model.getLabelGraphicInfo(elementId);
        FlowElement flowElement = model.getFlowElement(elementId);
        if (labelGraphicInfo != null
            && flowElement != null
            && StringUtils.isNotEmpty(flowElement.getName())) {
          xtw.writeStartElement(BPMNDI_PREFIX, ELEMENT_DI_LABEL, BPMNDI_NAMESPACE);
          xtw.writeStartElement(OMGDC_PREFIX, ELEMENT_DI_BOUNDS, OMGDC_NAMESPACE);
          xtw.writeAttribute(ATTRIBUTE_DI_HEIGHT, "" + labelGraphicInfo.getHeight());
          xtw.writeAttribute(ATTRIBUTE_DI_WIDTH, "" + labelGraphicInfo.getWidth());
          xtw.writeAttribute(ATTRIBUTE_DI_X, "" + labelGraphicInfo.getX());
          xtw.writeAttribute(ATTRIBUTE_DI_Y, "" + labelGraphicInfo.getY());
          xtw.writeEndElement();
          xtw.writeEndElement();
        }

        xtw.writeEndElement();
      }
    }

    // end BPMN DI elements
    xtw.writeEndElement();
    xtw.writeEndElement();
  }