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XML DOM Processing in ABAP part I - Convert an ABAP table into XML file using SAP DOM Approach.
Robert Eijpe

Introduction
With NetWeaver 04 SAP introduced simple transformations, a new way of converting XML directly into ABAP tables, structures and fields. Tobias Trapp wrote 5 weblogs about this topic with the title XML processing in ABAP. However the success of these great weblogs, you must have at least a SAP WAS 6.40 environment and you have to learn the Simple Transformation Language. At first another solution was introduced by SAP into the SAP kernel of version 4.6D. This implementation is called the iXML package and could be accessed using and ABAP Object class CL_IXML and about 40 ABAP Object interfaces IF_IXML*. In this weblog I will focus on the possibilities of SAP XML Document Object Model (DOM) processing at the ABAP stack. My objective is to explain how you can use it in abap mapping. For this I split this weblog into three parts. This first part will focus on the conversion of an abap table into an xml file. The second part will focus on the conversion from an xml file (back) to abap tables. The last part will deal with the use of SAP DOM within XI abap mapping, introduced with SAP XI 3.0.

The XML
In this weblog part we will create an xml file on the user’s computer based on data from an SAP system. First we will fill an internal table with SAP data.


Next we will create a document object using an iXML factory. This document can be filled with the data of the internal table. The document object can be represented as a tree structure, the so called Document Object Model or SAP DOM..


After filling the document object, we will transfer it into a XML stream. This stream is the binary version of the XML file and can be represented as a string, an xstring or a table with binary fields.


In the last step we will transfer the XML file to the user’s PC.

The implementation
In this implementation we will only focus on the creation of the XML file and the transfer to the user. You can not create a XML document directly. You have to use a so called ixml factory first.

TYPE-POOLS: ixml.
DATA: l_ixml TYPE REF TO if_ixml.
l_ixml = cl_ixml=>create( ).

This iXML factory can create an empty XML document object named l_document.

DATA: l_document TYPE REF TO if_ixml_document.
l_document = l_ixml->create_document( ).

At this point you can add the nodes (elements, attributes) into the document. First you have to declare the root element node.

DATA: l_element_root TYPE REF TO if_ixml_element.

This node we have to give a name and add it (create_simple_node) to the document object l_document, which will be the parent of this node.

l_element_root = l_document->create_simple_element(
name = 'flights'
parent = l_document ).

Next we can add child nodes to there parent node using the same method of the document object.

DATA: l_element_airline TYPE REF TO if_ixml_element,
l_element_airline = l_document->create_simple_element(
name = 'airline'
parent = l_element_root ).

An attribute can be add easily using the method set_attribute of the element node.

l_rc = l_element_airline->set_attribute( name = 'code' value = 'LH401' ).

Now we have finished the document object. Regretfully it can not be displayed in any form due to the fact that it is a binary object.
The next step is to convert the created document to a flat file. To achieve this we have to create a stream factory, which will help us to create an output stream.

DATA: l_streamfactory TYPE REF TO if_ixml_stream_factory.
l_streamfactory = l_ixml->create_stream_factory( ).

In this case, we will convert the document into an output stream which is based on an internal table of type x.

TYPES: BEGIN OF xml_line,
data(256) TYPE x,
END OF xml_line.
DATA: l_xml_table TYPE TABLE OF xml_line,
l_xml_size TYPE i,
l_rc TYPE i,
l_ostream TYPE REF TO if_ixml_ostream.
l_ostream = l_streamfactory->create_ostream_itable( table = l_xml_table ).

When we have created the output stream we can do the rendering from the document into the stream. The XML data will be stored in the internal table automatically.

DATA: l_renderer TYPE REF TO if_ixml_renderer.
l_renderer = l_ixml->create_renderer( ostream = l_ostream
& nbsp; document = l_document ).
l_rc = l_renderer->render( ).

In the last step we upload the file to the sapgui

l_xml_size = l_ostream->get_num_written_raw( ).

CALL METHOD cl_gui_frontend_services=>gui_download
EXPORTING
bin_filesize = l_xml_size
filename = 'c:\temp\flights.xml'
filetype = 'BIN'
CHANGING
data_tab = l_xml_table
EXCEPTIONS
OTHERS = 24.


This finished the first step-of-three. As mentioned before the next log will focus on the conversion from xml files (back) to abap tables.

A complete example
ABAP Source