For vRO Workflow alot of Attributes and Parameters are used. I want to get the list all these Attributes and Parameters, anyone who can help me in same?
I don't understand your question. Attributes and parameters are just input objects to workflows that can be anything.
Lets take the example of one parameter hostName (this one is in camel case). Where these are defined?
It would be defined in your workflow as either an input parameter or an attribute. But that by itself does nothing. You have to use hostName in your workflow elements for it to be valid.
On your workflow, try clicking the Parameters References tab. That will list out all of your parameters (and attributes if you toggle the check box) and can give you a sense of what is being consumed/returned across your logic.