Based on the book trading scenario below $($reproduced from Chapter $2$ of the Java Agent Development $($JADE$)$ tutorial $(2009)),$ write a Java program $($not in JADE$),$ to simulate the agent behaviour and transactions as described in this scenario. Note that the interactions follow a variant of the Contract$-$Net protocol. $[$Hint: For this simulation, agents do not need to be physically distributed and can therefore invoke each other's methods directly and no network programming is required.$]$

This scenario includes some agents selling books and other agents buying books on behalf of their users. Each buyer agent receives the title of the book to buy $($the $$target book$)$ as a command line argument $($or otherwise$)$ and periodically requests all known seller agents to provide an offer. As soon as an offer is received the buyer agent accepts it and issues a purchase order. If more than one seller agent provides an offer the buyer agent accepts the best one $($lowest price$).$ Having bought the target book the buyer agent terminates the interaction. You may wish to include a broker agent, which can facilitate the interactions between buyer agents and seller agents, but this is entirely optional.

Each seller agent has a minimal user interface by means of which the user can insert new titles $($and the associated price$)$ in the local catalogue of books for sale. Seller agents continuously wait for requests from buyer agents. When asked to provide an offer for a book they check if the requested book is in their catalogue and in this case reply with the price. Otherwise they do not respond $($refuse$).$ When they receive a purchase order they serve it and remove the requested $($copy of the$)$ book from their catalogue.

All issues related to electronic payment are beyond the scope of this exercise.