Create a Real Time Collaborative Bidding Engine: 
User Types: 
1. Bid Creators 
2. Bidders

Use Cases for : 
1. Bid Creators: 
a. Create a bid with title & one or more BID_ITEMS (with description) you want to place for bidding under one bidding request. 
b. Invite BIDDERS to participate in the bidding 
c. Set Start AND End time for the BID 
d. PUBLISH the bid, this is when invites go to bidders and the BID is instantiated 
e. MONITORS all BIDS with real-time leader board of PARTICIPANTS 
f. Once bids end, should be able to view Bid summary with all participants bid information 
2. BIDDERS: 
a. ACCEPT/REJECT bid requests 
b. Once Accepted, place amount across item(s) present in the Bid Request 
c. Should be able to see their current Rank (real-time) in the Bid 
d. Should be able to update the amount any number of times until the BID closes to improve their rank, if needed.