Karajan Workflow Formats: .k and .xml

In CoGKit, there are two supported formats in Karajan workflow -- .k and .xml.
Personally, I like xml because of its prevalence and openness. There are many handy tools which can process xml documents in various ways. Unfortunately, xml support in Karajan workflow is not comprehensive. In recent programming, I need to use element dag which is used to support Directed Acyclic Graph.
(1) At first, Karajan workflow supports DAG. But it does not give users a dag.xml file to import. Instead, just dag.k is provided. So I need to find a way to convert dag.k to dag.xml. Thank Mike and Gregor to help me get out of the struggle. Following method can be used to do the task:

cog-workflow -intermediate dag.k

Although following error pops up, I still can get the file I need (dag.xml).

Execution failed:
Variable not found: #channel#defs
        kernel:export @ dag.k, line: 44

Note: actually, what is generated is dag.kml not dag.xml. Currently, I assume they are the same because I have no better choice.

(2) In document I can find, sample workflows about DAG are written in .k format.
This is the unique resource I find helpful: http://wiki.cogkit.org/index.php/Java_CoG_Kit_Workflow_Guide#Direct_Acyclic_Graphs.
Once again, I used command cog-workflow to do this task. But the generated .kml(xml) file is lengthy and not appropriate for human readers. So, I decided to convert it manually by myself. I found this useful link(http://wiki.cogkit.org/index.php/Java_CoG_Kit_Karajan_Workflow_Reference_Manual_4.1.5) which describes both formats in detail.