code:     public Document getMetaData(Idp config, TrustedIdp serviceConfig) throws ProcessingException {
  
          try {
              Crypto crypto = CertsUtils.createCrypto(config.getCertificate());
              
              W3CDOMStreamWriter writer = new W3CDOMStreamWriter();
  
              writer.writeStartDocument("UTF-8", "1.0");
  
              String referenceID = IDGenerator.generateID("_");
              writer.writeStartElement("md", "EntityDescriptor", SAML2_METADATA_NS);
              writer.writeAttribute("ID", referenceID);
              
              String serviceURL = config.getIdpUrl().toString();
              writer.writeAttribute("entityID", serviceURL);
              
              writer.writeNamespace("md", SAML2_METADATA_NS);
              writer.writeNamespace("fed", WS_FEDERATION_NS);
              writer.writeNamespace("wsa", WS_ADDRESSING_NS);
              writer.writeNamespace("auth", WS_FEDERATION_NS);
              writer.writeNamespace("xsi", SCHEMA_INSTANCE_NS);
  
              if ("http://docs.oasis-open.org/wsfed/federation/200706".equals(serviceConfig.getProtocol())) {
                  writeFederationMetadata(writer, serviceConfig, serviceURL);
              } else if ("urn:oasis:names:tc:SAML:2.0:profiles:SSO:browser".equals(serviceConfig.getProtocol())) {
                  writeSAMLMetadata(writer, serviceConfig, serviceURL, crypto);
              }
              
              writer.writeEndElement(); // EntityDescriptor
  
              writer.writeEndDocument();
              
              writer.close();
  
              if (LOG.isDebugEnabled()) {
                  String out = DOM2Writer.nodeToString(writer.getDocument());
                  LOG.debug("***************** unsigned ****************");
                  LOG.debug(out);
                  LOG.debug("***************** unsigned ****************");
              }
  
              Document result = SignatureUtils.signMetaInfo(crypto, null, config.getCertificatePassword(), 
                                                            writer.getDocument(), referenceID);
              if (result != null) {
                  return result;
              } else {
                  throw new RuntimeException("Failed to sign the metadata document: result=null");
              }
          } catch (ProcessingException e) {
              throw e;
          } catch (Exception e) {
              LOG.error("Error creating service metadata information ", e);
              throw new ProcessingException("Error creating service metadata information: " + e.getMessage());
          }
  
      }
  
  