How to debug ABAP mapping

Question

Hello
I've built a ABAP mapping based on How To convert an IDoc-XML structure to a flat file and vice versa in XI 3.0, however it runs into exeception when I tested it in SXI_MAPPING_TEST with error;
- <cls:CX_SY_NO_HANDLER id="o265">
- <CX_ROOT>
  <TEXTID>1F09B73915F6B645E10000000A11447B</TEXTID>
  <PREVIOUS href="#o266" />
  <KERNEL_ERRID>UNCAUGHT_EXCEPTION</KERNEL_ERRID>
  <IS_RESUMABLE />
- <INTERNAL_SOURCE_POS>
  <PROGID>217</PROGID>
  <CONTID>5192</CONTID>
  </INTERNAL_SOURCE_POS>
  </CX_ROOT>
  <CX_NO_CHECK />
- <CX_SY_NO_HANDLER>
  <CLASSNAME>CX_SY_REF_IS_INITIAL</CLASSNAME>
  </CX_SY_NO_HANDLER>
  </cls:CX_SY_NO_HANDLER>
I want to debug into the mapping class, someone said jsut set break point in the mapping class and run sxi_mapping_test, then I would be able to debug. However this doesn't work, the execution doesnot stop at the break point (I set session break point, not external break point). Somebody can help?
Thanks
Eric

Answer 1

The trace I got is like:
  <?xml version="1.0" encoding="iso-8859-1" ?>
- <Top>
  <First>BeginTrace</First>
  <Trace level="1" type="B">CL_MAPPING_XMS_PLSRV3-ENTER_PLSRV</Trace>
  <Trace level="2" type="T">......attachment XI_Context not found</Trace>
  <Trace level="3" type="T">Mapping is determined</Trace>
  <Trace level="1" type="T">Interface Mapping http://mynamespace/xi OM_Order_to_Simple</Trace>
  <Trace level="3" type="T">Object ID of Interface Mapping F1B943B7E3EB382FB1334066F113E0E6</Trace>
  <Trace level="3" type="T">Version ID of Interface Mapping EAA847208A4B11DD96D8F1C80AD60A0B</Trace>
  <Trace level="3" type="T">Mapping Steps 1 R3_ABAP Z_ABAP_MAPPING_IDOC_TO_FLAT</Trace>
  <Trace level="3" type="T">MTOM Attachments are Transferred to the Payload</Trace>
  </Top>