public DatanodeRegistration getDNRegistrationForNS(int namespaceId) 
  throws IOException {
    NamespaceService nsos = namespaceManager.get(namespaceId);
    if(nsos==null || nsos.getNsRegistration()==null) {
      throw new IOException("cannot find NSOfferService for namespaceId="+namespaceId);
    }
    return nsos.getNsRegistration();
  }
public DatanodeRegistration getDNRegistrationForNS ( int namespaceId ) throws IOException { NamespaceService nsos = namespaceManager . get ( namespaceId ) ; if ( nsos == null || nsos . getNsRegistration ( ) == null ) { throw new IOException ( "cannot find NSOfferService for namespaceId=" + namespaceId ) ; } return nsos . getNsRegistration ( ) ; }
get datanode registration by namespace id
@param namespaceId
@return datanode registration object
@throws IOException