jackal

Auction Sniper for learning along with the example from the book "Growing Object-Oriented Software Guided By Tests"

Terms

Some basic terms

• Item is something that can be identified and bought.
• Bidder is a person or organization that is interested in buying an item.
• Bid is a statement that a bidder will pay a given price for an item.
• Current price is the current highest bid for the item.
• Stop price is the most a bidder is prepared to pay for the item.
• Auction is a process for managing bids for an item.
• Auction house is an institution that hosts auctions.

Givens

• There is an auction for every item, an items identifier can be used to refer to its auction.
• Handling of bought items is not necessary.

UI

• Build the UI as a web interface
• It will allow a user to bid for multiple items at a time
• It will show the identifier, stop proce, and the current auction price and status for each item it's sniping
• Buyers will be able to add new items for sniping through the UI and the displa values will change in response to events arriving from the auction house

Auction Protocol

with XMPP

Bidders send commands:

** Join** bidder joins action. Sender identifies the bidder, name of chat session identifies the item Bid bidder sends bidding price to auction

Auctions send events:

Price send to a bidder when he joins, and to all whenever a new bid has been acceptes. reports currently accepted price, the bidder who bid it and the minimum increment for the next bid Close announces the close of an action, the winner of the last price event has won the auction

A Sniper joins an auction, there are some rounds of bidding until the auction closes and the Sniper will either have won or lost

Example {{{ SOLVersion: 1.1; Command: JOIN; SOLVersion: 1.1; Event: PRICE; CurrentPrice 192; Increment: 7; Bidder: Someone else; SOLVersion: 1.1; Command: BID; Price 199; SOLVersion: 1.1; Event: CLOSE; }}}

To bid for an item 12345 a client starts a chat with auction-12345

First steps

Single item: join, lose without bidding Single item: join, bid and lose Single item: join, bid and win Show price details Multiple items Add items through the UI Stop bidding at the stop price

Test setup

For the openfire server, use the docker-compose file. Add accounts with password

• sniper / sniper
• auction-item-54321 /action
• auction-item-65432 / auction