Can UML diagrams be exported out of DNG, as UML, for reuse in other tools, and/or documents?
One answer
Which version of RDNG are you referring to? Are you really sure it's UML?
For RDNG 6.0 "Diagram" format, you can simply do a OSLC GET call (with HTTP headers "Accept: application/rdf+xml" and "OSLC-Core-Version: 2.0") to the requirement resource URI, can get the diagram source in the <rm:diagram> tag.
If I'm not mistaken, it's based on JGraphX (or mxGraph).
http://www.mxgraph.cn/doc/mxgraph/index_javavis.html
https://jgraph.github.io/mxgraph/docs/tutorial.html
For older versions of RDNG, or the "old sketch", the format is of a less known specification as well, but I can't remember the name now.
In both cases, you will need to do a conversion to the Visio format, probably by writing your own code.
For RDNG 6.0 "Diagram" format, you can simply do a OSLC GET call (with HTTP headers "Accept: application/rdf+xml" and "OSLC-Core-Version: 2.0") to the requirement resource URI, can get the diagram source in the <rm:diagram> tag.
If I'm not mistaken, it's based on JGraphX (or mxGraph).
http://www.mxgraph.cn/doc/mxgraph/index_javavis.html
https://jgraph.github.io/mxgraph/docs/tutorial.html
For older versions of RDNG, or the "old sketch", the format is of a less known specification as well, but I can't remember the name now.
In both cases, you will need to do a conversion to the Visio format, probably by writing your own code.