Using XSLT

Question

I created an XSLT transformation called "ZSIMPLEXSLT" and wrote the following code to try and transform some data on a web server.  When the code gets to the CALL TRANSFORMATION line it bombs saying that I've tried to invoke a method on an object reference that's null.  It's talking about <b>istream</b> because in the Globals list I can see this dataobject is still INITIAL.  Does anybody know why the call to create_istream_uri( ) is failing to return an istream?
TYPE-POOLS: abap.
TYPE-POOLS: ixml.
CLASS cl_ixml DEFINITION LOAD.
DATA g_ixml         TYPE REF TO if_ixml.
DATA streamfactory  TYPE REF TO if_ixml_stream_factory.
DATA istream        TYPE REF TO if_ixml_istream.
DATA xmlstr         TYPE string.
DATA ex             TYPE REF TO CX_SY_REF_IS_INITIAL.
DATA imsg           TYPE REF TO IF_MESSAGE.
DATA smsg           TYPE string.
START-OF-SELECTION.
  g_ixml = cl_ixml=>create( ).
  streamfactory = g_ixml->create_stream_factory( ).
  istream = streamfactory->create_istream_uri( 'http://www.somewhere.com/data.xml' ).
  TRY.
    CALL TRANSFORMATION zsimplexslt
      SOURCE XML istream
      RESULT XML xmlstr.
  CATCH CX_SY_REF_IS_INITIAL INTO ex.
    imsg = ex.
    WRITE / 'EXCEPTION THROWN:'.
    smsg = imsg->GET_LONGTEXT( ).
    smsg = imsg->GET_TEXT( ).
    WRITE / smsg.
  ENDTRY.

Answer 1

Hello Steve
I am not sure whether method
streamfactory->create_istream_uri is able to make a HTTP connection to a web site. All the sample reports in package SIXML_TEST (ECC 5.0) deal with files located either on the local PC or the application server.
However, as a workaround you could use interface IF_HTTP_CLIENT in order to establish a HTTP connection and retrieve the data from the web site. The following sample report ZUS_SDN_SIMPLE_XSLT is a mélange of your coding and pieces out of report RSHTTP02 (HTTP client test, package SHTTP). 
*& Report  ZUS_SDN_SIMPLE_XSLT
REPORT  zus_sdn_simple_xslt.
TYPE-POOLS: abap.
TYPE-POOLS: ixml.
CLASS cl_ixml DEFINITION LOAD.
DATA g_ixml         TYPE REF TO if_ixml.
DATA streamfactory  TYPE REF TO if_ixml_stream_factory.
DATA istream        TYPE REF TO if_ixml_istream.
DATA xmlstr         TYPE string.
DATA x_string       TYPE xstring.
DATA ex             TYPE REF TO cx_sy_ref_is_initial.
DATA imsg           TYPE REF TO if_message.
DATA smsg           TYPE string.
DATA:
  go_client    TYPE REF TO if_http_client.
START-OF-SELECTION.
  g_ixml = cl_ixml=>create( ).
  streamfactory = g_ixml->create_stream_factory( ).
  CALL METHOD cl_http_client=>create_by_url
    EXPORTING
      url                = 'http://www.w3schools.com/xsl/cdcatalog.xml'
*      PROXY_HOST         =
*      PROXY_SERVICE      =
*      SSL_ID             =
*      SAP_USERNAME       =
*      SAP_CLIENT         =
    IMPORTING
      client             = go_client
    EXCEPTIONS
      argument_not_found = 1
      plugin_not_active  = 2
      internal_error     = 3
      OTHERS             = 4.
  IF sy-subrc <> 0.
*   MESSAGE ID SY-MSGID TYPE SY-MSGTY NUMBER SY-MSGNO
*              WITH SY-MSGV1 SY-MSGV2 SY-MSGV3 SY-MSGV4.
  ENDIF.
  go_client->request->set_method( 'GET' ).
  go_client->request->set_version(
       if_http_request=>co_protocol_version_1_0 ).
  cl_http_utility=>set_request_uri( request = go_client->request
                                    uri     = 'GET' ).
  CALL METHOD go_client->send( ).
  CALL METHOD go_client->receive( ).
  x_string = go_client->response->if_http_entity~get_data( ).
  istream = streamfactory->create_istream_xstring( x_string ).
**  CALL METHOD streamfactory->create_istream_uri
**    EXPORTING
***      public_id = 'http://www.w3schools.com/xsl/cdcatalog.xml'
**      system_id = 'http://www.w3schools.com/xsl/cdcatalog.xml'
**    RECEIVING
**      rval      = istream.
  CHECK ( istream IS BOUND ).
**  istream = streamfactory->create_istream_uri(
**    'http://www.w3schools.com/xsl/cdcatalog.xml' ).
  TRY.
      CALL TRANSFORMATION zsimplexslt
        SOURCE XML istream
        RESULT XML xmlstr.
    CATCH cx_sy_ref_is_initial INTO ex.
      imsg = ex.
      WRITE / 'EXCEPTION THROWN:'.
      smsg = imsg->get_longtext( ).
      smsg = imsg->get_text( ).
      WRITE / smsg.
  ENDTRY.
Regards
  Uwe
PS: Please forgive that I have renamed your report but it makes tracking of "my" sample reports in the SDN easier...