Critical parts goes below Re-order pt - to trigger email via Workflow

Question

Hi Experts,
I am new to workflow and here is my requirement.
When Material goes below Re-order pt in MM , MRP runs and creates PR/Sch Line. I want to trigger email to some Group when few Critical parts goes below Re-order point via Workflow
A workflow should trigger and get email to Group I saw one standard workflow (WS03100020) but I dont know how to active and how it will work.
I can copy this to custom workflow using PFTC and do, but when the material document creates - Means Critical parts are consumed and Stock level goes below re-order point. how my copied custom workflow triggers?
Critical Parts A , C , F, X  and Z
If Material  A ,C and F goes below re-order pt then email to trigger to GROUP1.
If Material X and Z goes below re-order pt then email to trigger to GROUP2.
Need to know :
1) steps to copy and modify
2) How to Execute manually
3) How to execute automatically when Material stock falls below re-order point. ( Lets say in MM03 Re-order pt is 5 ) and IN MMBE current stock is 20, when there is consumption ( Material DOcument to Cost center - Mvtype 201 ) for 16 QTY.. then my Custom or Standard Workflow should Trigger and should get a email to Group.
How to achieve this. Please explain me with Step. Highly apprieciate your help and will reward points
Thanks in advance.
Bala M

Answer 1

o.k. lets first handle the check function module
you need to start from the key and run the check is it higher or lower then the reorder point,
if it's higher, raise an exception (use message... raising), else do noting.
test the function module directly and see if it works, then look at the event trace(SWEL) and see what happens when your event is raised, if it's higher then the reorder point you should see an error (specific linkage is red and the message you entered in the function module in the details) else the event linkage should be o.k (green).
now for the function itself: if you use the cl_bcs to send the mail, you do not need to link SWW_WI_CREATE_VIA_EVENT_IBF as the receiver function module, but the function module you create to send the mail. again test the function module directly first and only then link it to the event.
if you want to send the mail by workflow see the link in my earlier reply.