snippets/liferay/camunda-bpm-liferay-tasklist/src/main/java/org/camunda/demo/liferay/tasklist/TasklistBean.java
public String getPortletId(String portletName, String servletContextName) {
    String portletId = portletName;

    if (Validator.isNotNull(servletContextName)) {
      if (servletContextName.startsWith("/")) {
        servletContextName = servletContextName.substring(1);
      }
      portletId = portletId.concat(PortletConstants.WAR_SEPARATOR).concat(servletContextName);
    }

    portletId = PortalUtil.getJsSafePortletId(portletId);
    return portletId;
  }
public String getPortletId(String portletName, String servletContextName) {
    String portletId = portletName;

    if (Validator.isNotNull(servletContextName)) {
      if (servletContextName.startsWith("/")) {
        servletContextName = servletContextName.substring(1);
      }
      portletId = portletId.concat(PortletConstants.WAR_SEPARATOR).concat(servletContextName);
    }

    portletId = PortalUtil.getJsSafePortletId(portletId);
    return portletId;
  }
copied from
https://github.com/liferay/liferay-portal/blob/master/portal-impl
/src/com/liferay/portal/service/impl/PortletLocalServiceImpl.java

see
http://stackoverflow.com/questions/11151001/how-to-get-portlet-id-using-
the-portlet-name-in-liferay