Question

Case Study

Hershee’s Chocolates makes an assortment of chocolate candy and candy novelties. The company has six in-city stores, five stores in major metropolitan airports, and a small mail order branch. Hershee’s has a small, computerized information system that tracks inventory in its plant, helps schedule production, and so on, but this system is not tied directly into any of its retail outlets. The mail order system is handled manually.

Recently, several Hershee’s stores experienced a rash of complaints from mail order customers that the candy was spoiled upon arrival, that it did not come when promised, or that it never arrived; the company also received several letters complaining that candy in various airports tasted stale. Hershee’s has been selling a new, low-carb, dietetic form of chocolate made with sugar-free, artificial sweetener. Sales have been brisk, but there have been problems shipping the wrong type of chocolate to an address with a diabetic person. There were a number of complaints and Hershee’s sent a number of free boxes of chocolate to ease the situation.

Management would like to sell products using the Web but only has a few Web pages with information about the company and an order form that could be printed. Web ordering does not exist. One of the senior executives would like to sell customized chocolates with the name of a person on each piece.

Although the production area has assured management that this could be easily done, there is no method to order customized chocolates. Another senior executive has mentioned that Hershee’s has partnered with several European chocolate manufacturers and will be importing chocolate from a variety of countries. At present, this must be done over the phone, with email, or by mail. The executive wants an internal website that will enable employees to order directly from the partner companies. All this has led a number of managers to request trend analysis. Too much inventory results in stale chocolate, whereas at other times there is a shortage of a certain kind of chocolate.

Seasonal and holiday variation trends would help Hershee’s maintain an adequate inventory. The inventory control manager has insisted that all changes must be implemented before the next holiday season. “The time for this to be complete is an absolute due date,” remarked Candy, a senior manager. “Make sure that everything works perfectly before the site goes public,” she continues, “I don’t want any customers receiving the wrong orders!” In addition, the order processing manager has mentioned that the system must be secure.

Construct an Ideal Object Model from the case study above.

Answer 1

Explanation :

Object Model :

• An object model is a logical interface, software or system that is modeled through the use of object-oriented techniques. It enables the creation of an architectural software or system model prior to development or programming.
• An object model is part of the object-oriented programming (OOP) lifecycle.
• The object model visualizes the elements in a software application in terms of objects.
• The object model encompasses the principles of abstraction, encapsulation, modularity, hierarchy, typing, concurrency, and persistence and these elements are brought together in a synergistic fashion.
• The object model identifies the classes in the system and their relationship, as well as their attributes and operations.
• It represents the static structure of the system.
• The object model is represented graphically by a class diagram.

Features of Object Model :

An object model consists of the following important features:

• Object Reference : Objects can be accessed via object references. To invoke a method in an object, the object reference and method name are given, together with any arguments.
• Interfaces : An interface provides a definition of the signature of a set of methods without specifying their implementation. An object will provide a particular interface if its class contains code that implement the method of that interface. An interface also defines types that can be used to declare the type of variables or parameters and return values of methods.
• Actions : An action in object-oriented programming (OOP) is initiated by an object invoking a method in another object. An invocation can include additional information needed to carry out the method. The receiver executes the appropriate method and then returns control to the invoking object, sometimes supplying a result.
• Exceptions : Programs can encounter various errors and unexpected conditions of varying seriousness. During the execution of the method many different problems may be discovered. Exceptions provide a clean way to deal with error conditions without complicating the code. A block of code may be defined to throw an exception whenever particular unexpected conditions or errors arise. This means that control passes to another block of code that catches the exception.

Steps of Object Modelling :

The following steps are performed in constructing an object model:

1. Read carefully, the problem statement.
2. Locate the object classes by underlining nouns.
3. Remove unnecessary and incorrect classes.
4. Prepare a data dictionary.
5. Locate associations between object classes.
6. Remove unnecessary and incorrect attributes.
7. Use inheritance to share common structure.
8. Traverse access paths to identify deficiency.
9. Remove unnecessary and incorrect associations.
10. Locate attributes of the object classes.

In the light of the above discussions, the solution to the given case scenario is as follows:

The Solution :

The outline of an Ideal Object Model for Hershee's Chocolates is depicted in the diagram below:

CUSTOMER EMPLOYEE

customer_id ( pk ) employee_id ( pk )

custmer _name custmer _name

address emp _branch

place_order ( )     place_order ( )

      

  ORDER

TRANSACTION    order_id ( pk )

transaction _id ( pk )      for_customer_id

cust_id    by_employee_id

order_id    address

delivery _id    delivery_time

payment_id    delivery_id

get_payment ( )    payment_id

deliver ( ) inherits inherits

CUSTOMISED_ORDER IMPORT_ORDER

customised_Name import_Partner

This concludes the design of the Ideal Object Model for the given scenario along with the necessary explanations.

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