Problem : Client Server Trading System in C programming language
A Client-Server Based Trading System is to be designed with the following specifications. There will be a
set of traders who will trade with each other in the automated system. There will be a Server which will
register requests from traders for buying and selling quantities of Items. The Server will also match the
buy with the sell requests from different traders based on certain price rules (given below).
Traders will log on to the trading system through the trading client. They will have the option to view the
currently available items (for buy/sell), their quantities and their prices. They will also send requests for
buying and selling items and specify the quantity and price. Traders will also have the option to view their
matched trades at any time. There are ten known items which the traders can trade in with their codes
from 1 to 10. There will be a maximum of 5 traders (with codes from 1 to 5) who can log on to the
system and work. One trader can work from one client at a time only.
The functionalities of any client will be:
• Login to the System: The trader will execute the client, give the trader number and will
be logged in. After that he/she will have the following options in a menu. Several clients
will login (from different terminals) and trade simultaneously.
• Send Buy Request: The trader will send a buy request by stating the item code, the
quantity and unit price.
• Send Sell request: The trader will send a sell request by stating the item code, the
quantity and unit price.
• View Order Status: The Trader can view the position of buy and sell orders in the
system. This will display the current best sell (least price) and the best buy (max price)
for each item and their quantities.
• View Trade Status: The trader can view his/her matched trades. This will provide the
trader with the details of what orders were matched, their quantities, prices and
There will be only one server which will be running and perform the functions of order
processing and trade matching in addition to acknowledging logins by clients and servicing
their requests. The order processing will be as follows. There will be a buy and a sell order
queue for each item. On receiving buy/sell order request from a trader, the server will put it in
the appropriate order queue. If there is a possibility of a trade match, then that trade match will
take place, the traded items will be appropriately updated and the result of the trade along with
the details of the counterparties, item, quantity and price will be stored in the traded set. The
matching rule is as follows:
On a buy Request at price P and quantity Q of an item I, the server will check if there is
any pending sell order for the same item at price P’ ≤ P.
Among all such pending sell orders, the match will be made with the one having the least
If both have same quantity, i.e., Q’ = Q, then both these orders will be removed from
their respective queues and the result will be put into the traded set.
If Q’ > Q then the buy request will be fully traded and the remaining part, i.e., Q’ – Q of
the sell order will remain in the sell queue at the same price P’.
On the other hand, if Q’ < Q then the sell order will be fully traded and the remaining
buy order will be tested for more matches.
If the buy order cannot be matched, it will be put into the buy queue.
A similar rule will apply for a sell request.
All these requests will be handled in a FCFS basis.
Note that the buy and sell queues are shared by the traders (so, mutual exclusion must be
(Needs Socket programming, semaphores, shared memory and signal handler