The following piece of literature is a guide for the management of Ernest Naylor regarding the system created to model the current activities of the organisation. In addition to this, a prototype database was created that could form the basis of a full scale model to aid in the activities within the organisation which have been modeled in detail in the following report. Each stage in the modeling of the system includes a diagram for the ease of understanding of the processes involved and each diagram is accompanied by a small description summarising the activities described in the diagram.
Rational Rose was used to model the system as it allows for a greater understanding of the system and is a simple method that can be easily followed to provide an in depth study of the system and its environment. Other possibilities to model the system included Structured Systems Analysis and Design. However it was felt that modeling the system using the Unified Modelling Language (UML) would be more beneficial due to its adaptability and understandability for the user.
Criticism of methods used SSADM was very successful, any methodology that attempts this degree of coordination tends to grow large and unwieldy, partly due to the need for continual checking and cross-referencing between separate models. Object Modeling Techniques (OMT), class diagram notation was incorporated into UML almost unaltered. But, unlike UML, OMT is more than a language, or set of techniques and notations. Both the OMT and Structured System Analysis and Design (SSADM), consist of similar modeling components. They both support the same views of a system: the object, functional and dynamic models.
The differences between them are the emphasis and style. In SSADM, the dominating view is the functional model whereas in the UML it is the object model. OMT organises the system around the real world objects, compared to the SSADM, which organises the system around procedures. Changes in requirements cause problems for SSADM because procedure based designs do not reflect change easily, this also causes problems with extendibility to the system, whereas the OMT can accommodate the change easier and extendibility can be implemented.
In Object-Oriented Analysis (OOA) the users and developers of the system are brought together, uniting them with a common vocabulary drawn from the domain. In the object-orientated approach the system is designed with the context of real world objects in mind. Object Orientated Methods including UML have evolved to help developers exploit their expressive power (Coad and Yourdon 1991) . Some of the benefits are listed below: Use cases show the functionality of the system from the users’ perspective.
They document the scope of the system and the developer’s understanding of what it is that the users require. The use cases diagram shown below has three aspects of the system: actors, use cases and the system boundary. Actors represent the roles that people take on when communicating with the particular use cases in the system. One actor can represent several people or job titles. In the diagram shown below, OrderClerk is an actor and the order material is the use case. Use cases can provide a step-by-step breakdown of the interaction between the user and the system for each particular use case.
Class Diagram The class diagram is derived from the use case and is developed for each use case. We know from the use case diagram that the OrderClerk is the actor for the use case order material. The use case description tells us that the clerk is responsible for ordering materials. As you can see below, class names are always written in the singular, for example, for the class name ‘customer’, it can be seen below that it is written in singular although there are many number of customers.
Attributes are part of the essential description of a class. Examples of these are: Name, CompanyName and etc, for the class ‘surveyor’. They are the common structure of what a member can know. This means, a member can know the name of the surveyor and the company name too. A class is sub-divided into three compartments: the top compartment contains the class name, the second contains the attribute names and the third contains operations. Operations are the action that is carried out by an object.
An example of an operation for the class diagram “customer” is “Add New”. This allows new customers to be added to the system. Interaction Diagrams 1. Complete Estimate Sequence Diagram for Surveyor: A sequence diagram shows an interaction between objects, arranged in a time sequence. Its most common use is to represent the detailed object interaction that occurs for one use or one operation. It specifies the communication patterns between the roles in collaboration.