You can create much more complex XML output by using the CSV option on OUTPUT instead of the XML option. The XML option will only produce the straight-forward style of XML shown above. However, some applications require the use of XML attributes inside the tags. This code demonstrates how to produce that format:

CRLF := (STRING)x'0D0A';          
OutRec := RECORD
  STRING Line;
END;
OutRec DoComplexXML(InterestingRecs L) := TRANSFORM
SELF.Line := '  <area code="' + L.code + '">' + CRLF +
             '    <zone>' + L.timezone + '</zone>' + CRLF +
             '  </area>';
END;
ComplexXML := PROJECT(InterestingRecs,DoComplexXML(LEFT));
OUTPUT(ComplexXML,,'~PROGGUIDE::EXAMPLEDATA::OUT::Complextimezones301',
       CSV(HEADING('<?xml version=1.0 ...?>'+CRLF+'<timezones>'+CRLF,'</timezones>')),OVERWRITE);

The RECORD structure defines a single output field to contain each logical XML record that you build with the TRANSFORM function. The PROJECT operation builds all of the individual output records, then the CSV option on the OUTPUT action specifies the file header and footer records (in this case, the XML file tags) and you get the result shown here:

<?xml version=1.0 ...?>
<timezones>
  <area code="301">
    <zone>Eastern Time Zone</zone>
  </area>
  <area code="302">
    <zone>Eastern Time Zone</zone>
  </area>
  <area code="303">
    <zone>Mountain Time Zone</zone>
  </area>
</timezones>

So, if using the CSV option is the way to OUTPUT complex XML data formats, how can you access existing complex-format XML data and use ECL to work with it?

The answer lies in using the XPATH option on field definitions in the input RECORD structure, like this:

NewTimeZones := 
 DATASET('~PROGGUIDE::EXAMPLEDATA::OUT::Complextimezones301',
         {STRING area {XPATH('<>')}},
         XML('timezones/area'));

The specified {XPATH('<>')} option basically says "give me everything that's in this XML tag, including the tags themselves" so that you can then use ECL to parse through the text to do your work. The NewTimeZones data records look like this one (since it includes all the carriage return/line feeds) when you do a simple OUTPUT and copy the record to a text editor:

<area code="301">
  <zone>Eastern Time Zone</zone>
</area>

You can then use any of the string handling functions in ECL or the Service Library functions in StringLib or UnicodeLib (see the Services Library Reference) to work with the text. However, the more powerful ECL text parsing tool is the PARSE function, allowing you to define regular expressions and/or ECL PATTERN attribute definitions to process the data.

This example uses the TRANSFORM version of PARSE to get at the XML data:

{ds.code, ds.timezone} Xform(NewTimeZones L) := TRANSFORM
  SELF.code     := XMLTEXT('@code');
  SELF.timezone := XMLTEXT('zone');
END;
ParsedZones := PARSE(NewTimeZones,area,Xform(LEFT),XML('area'));

OUTPUT(ParsedZones);

In this code we're using the XML form of PARSE and its associated XMLTEXT function to parse the data from the complex XML structure. The parameter to XMLTEXT is the XPATH to the data we're interested in (the major subset of the XPATH standard that ECL supports is documented in the Language Reference in the RECORD structure discussion).