I have two groups containing nodes. I want to create links between them by first clicking one node and on the second click on the other node a link should be formed. Is that feasible?
Yes, you will need to create a new Tool class that handles multiple clicks (mouse down and mouse up events) and notices whenever the user clicks on two different nodes that meet your criteria for drawing a valid new link. When that happens you can call GraphLinksModel.addLinkData in a transaction.
The PolylineLinkingTool, http://gojs.net/latest/extensions/PolylineLinking.html and http://gojs.net/latest/extensions/PolylineLinkingTool.js, do something similar. However it involves incrementally extending the route of a new link, which is much more complicated than what you want to do.
Thanks Walter. I will try to implement this way.