External Documentation.txt

Northwind Server Implementation 
 We have given a task to build server for the defined protocol "Order3901/1.0" to interact with northwind client to place order.

Restrictions
- Only one client is allowed to interact with server at an instance.
- Server needs to be restarted when client shutdowns.

class
* Server
   The main server starting point.
  Methods
  -> Server
    Contructor defining all the required params (like port) to start a server.

  -> pullIncomingMessage
    Reads the incoming message from socket buffer


* MessageHandler
  Processes the incoming message and writes the ouput in the socket buffer.

  Methods
  -> incomingMessage
    Process the incoming message and decodes the header values.
    Checks for valid incoming message throws exception if error exists.

  -> processBody
    Reads the body content based on the header's content-length.

  -> performOperation
    Checks for valid user before performing any operation.
    Performs the given operation and handles the state exceptions.
    Handles any operation specific exception cases.

  -> WriteOutgoingMessage
    Writes the ouput to the ouput socket buffer from which client reads.
  
  -> shutdownConnection
    Clears all the user and order details

* MyIdentity
  Has username, password and database for identity purpose.

* northwind
  Has database operations and computations for northwind.

   Methods
   -> authenticate
      Checks for valid user using lastname and dateofbirth
   -> placeOrder
      Places the given order; Also checks for any invalid cases and throws exception.
      Inserts orderdetails on successfull order placement.
   -> listElements
      Lists the customer, products and products in the order based on the target
   -> checkProduct
      Checks whether the product added in current order is valid
* Order
  POJO class for storing order details

* Client
  POJO class for storing user  and session details


References
1) Generate random String of given size in Java. (2018, December 11). Retrieved from https://www.geeksforgeeks.org/generate-random-string-of-given-size-in-java/