Is it possible to have an element to do an external command? Webcall request, method call …etc?
Could you provide a bit more context to your question? Which library are you using?
Sure, what i am trying to do is create a workflow UI which is the front end for a list of rules or steps to done. I am looking at custom-modeler to create me own elements so that i know elementA is rule1 and it is connected to elementB.
From this i will be updating our backend db with the steps created in the work flow. Is that possible and am I looking at the correct library?
You look at a highly customizable BPMN 2.0 viewer / modeler.
The modeler reads BPMN 2.0 XML files and exports the changes as BPMN 2.0 XML. If you plan to export anything else (custom JSON or whatever) you could look into diagram-js, the underlying basis.
Depending on your back-end technology it is more or less straight forward to extract the flow information from the exported BPMN 2.0 XML files.