Passing parameters back & forth fm Workflow to Webdynpro

Hello Experts,

I am fairly new to workflow and I am hoping you can clear some of my basic questions. I am triggering a workflow from my webdynpro application (this works) like this -

CALL FUNCTION 'EWW_WORKFLOW_START'

EXPORTING

X_TASK = 'task number'

IMPORTING

Y_WORKFLOW_ID = WF_ID.

Can anyone throw more light on this WF_ID. I imported this value and its a integer value. Does this value remain the same throughout a workflow instance?

Can you please let me know what is the difference between WF_ID (Worflow Id) and wokitem id.

I am also researching on ways to pass parameters back and forth between my webdynpro app. (abap) and workflow. Would be very helpful, if you can give me a good starting point.

Appreciate all your help! Thanks, Liz