Object-Oriented Analysis: Identifying Classes From Use Case Diagrams

You will contribute to an online magazine for this module. Each of you will write an article of approximately 1000 – 1250 words on a topic that is loosely related to the lecture material.  The list of topics is in a wiki on blackboard, and only two students are permitted to write on each title.  Your articles will be published on Blackboard using the Module journal.  Your peers will give you feedback on your first draft.  Use this to refine your article for final publication.

 Together with your final revised article, you must also submit a brief analysis report (250 – 300 words) of changes you made and how they relate to the feedback you received. Hopefully, this will be a worthwhile learning experience for everyone. The deliverables are these (for deadlines see above):-

Use the module materials and your own research to write a magazine article (such as you might find in a professional publication such as Computing, Computer Weekly or BCS’s IT Now) that critically discusses the issues around one of the following titles:

1. Discuss why it may be seen as an advantage to use business processes as a way to identify analysis classes and thus also the software classes in an object-oriented system. Identify and compare other ways of identifying software classes.
2. Examine the case for the waterfall life cycle.  Does the waterfall life cycle still play a useful role in modern systems development, and if so, at which stages?
3. If we consider UML as 'just a modelling language' then it should not matter which methodology or life-cycle we use it within.  But is this true?  Discuss whether or not UML should be used only when the project life-cycle is iterative and incremental.
4. Is the use of a software development methodology necessary only for inexperienced developers?   Should the experienced staff also follow a methodology?  Discuss.
5. Are Agile Methods now no more than a fashion that has become out-of-date?
6. What is the best way to identify software classes from use cases?
7. In what circumstances would it not be appropriate to follow an iterative and incremental path? Why?
8. Explain what it means to say that Object Oriented modelling is ‘seamless’ throughout the life-cycle? Discuss whether this claim is justified or exaggerated.
9. The reuse of software and models is said to help make systems development more economical.  Which aspects of Object Oriented development actually achieve this benefit in practice?
10. Patterns were first applied to OO program design, but over time patterns have been identified for analysis, project management, systems architecture and more.  What are UML Profiles, and what is their value to the modelling process?
11. Agile Methods such as XP emphasise code over documentation.  A potential criticism is that those who have to maintain such systems appear to have very little information to tell them what it does and why it was designed that way.  Does this make XP a good choice of methodology?
12. Would it make sense to have a life-cycle that was iterative but not incremental?  Or one that was incremental but not iterative?  Why is the RUP life-cycle both?
13. Just how important is UML to the success of OO software projects today?  Discuss.
14. Does the spread of mobile and distributed computer systems present new challenges for systems analysts or designers? Critically analyse and discuss.
15. Agile Methods like DSDM and SCRUM appear to take as much control as they can away from senior managers and put it in the hands of the project team.  Is this is really such a good idea? 
16. In an iterative life-cycle, the activities of documenting requirements, analysing requirements, design, implementation and so on are all seen as ‘disciplines’ or activities that run through all the phases of the project life-cycle.  Explain and assess the advantages of organising a project this way.
17. What is Model Driven Architecture™?  Does it deliver any real benefits to the clients of systems development organisations? Explain.
18. Use Cases are not inherently object-oriented.  Why then is use case modelling so important in the OO approach?  Discuss.
19. Object-oriented development methods generally follow an iterative life-cycle – is this really necessary, or could you have OO without iteration?
20. “New systems development increasingly relies on software components developed outside the client organisation.”  First, is this statement true, and second, what does it imply for the activities of analysis and design?
21. UML does not include any advice or guidance about the sequence of activities within the life-cycle - that is the concern of methodology. But why should the notation for analysis and design be completely independent of the methodology? Explore this aspect of systems development.

Object-oriented modeling

Object-oriented analysis is technical approach for analyzing the system using different application, such as unified modeling language (UML), Object-oriented Programming, and many more ( Oliver, 2017). It is an approach, which divide a large project in small modules for better understanding for design. It makes more useable for the project designing. UML is helping for designing different diagrams for understanding actual requirements of a project in a visual view (Bruegge, 2008).

Use case diagrams are useful for understanding requirement in a proper format. It is also called behavior diagram. It describes use cases of system and collaboration with the external users, which is actor of use case diagram (Conallen, 2012).  In this report, section of classes from use case diagram will discuss in next parts.  

Object-oriented model is a best way for handling the project management life cycle and designing of a system. Object based approach provides dividing facility for a project. It divides complete system in small modules and provides accessing objects for them. UML is helpful for creating class diagrams and use case diagram of a project. A use case diagram is a coupling of different relations between actors and use cases (Gomaa, 2011).  

Use case diagrams are a coupling of different classes at a same place for understanding the data flow and control flow in the project. Identification of class from class diagram, and it is same as use cases in the use case diagrams. It will difficult when so many use cases are described in the same use case diagram (Siau & Lee, 2004). UML is a modeling language but so many people are thinking that it is a use case driven process. It is a way to show functional requirements of a project using use case diagram. Functional requirements are actions and services for particular situation and it is describe by the help of use case diagram (Tsang, et al., 2004).

Use cases are easier than accessing objects for users. Use care diagram are using use case model and it provides use case view. It is a process for capturing requirements and it provides all the information for analysis and design (Rumbaugh, et al., 2017). Use case-driven process use different use cases in the use case diagram and these are converted into classes in the class diagram. There are different approaches for the identification of classes from the use case diagrams (Larman, 2012).

One approach is based on noun and noun phrases in use cases description in use case diagram and it is like a class for class diagram. Next is checking every noun in the use case description and mapping them into classes. All approaches are having identification problem, which is common in object modeling (Van Lamsweerde, 2009). Use case description is having so many nouns so different unnecessary classes are created on the bases of them. Designers may use different categories for explaining the working of a system. Sometimes classes are conflict and it is making difficult to choose classes. Sometimes actors’ role is used for making classes.

Identifying classes from use case diagrams

Goal oriented approach is very good approach for identify classes from the use case diagrams. Classes are real world entity, which is participating in achieving the goal.

                                                 Source: (Liang, 2003) Generating class diagram from use case diagram.

There are seven steps for identifying classes from the use case diagram.

Goal of each use case: use cases are having separate goals for a function in project. Therefore, on the bases of goal of use cases identification is easier.

Entities identification: to achieve the goal entities are lays a good role in the use case. Entities are bind with the actors and provide description about the system with the help of use cases.

Specification of entities: this step is providing specification of entities with their features and it is used for generating class diagrams.

Referencing between different entities: proper references are used between entities for their association with classes. There are so many associations with the classes but proper entities references are used to generate the classes.

Identification of collaboration: for identification of classes, it is necessary to identify collaboration between entities and use cases of the use case diagram of a system.

Specification of collaboration: collaboration between use cases and entities is taking as an operation for a class. It is also helpful for the achieving the use case goals.

Testing of classes: testing is necessary.  It is good for identification of classes. It is helpful for the reducing complexity of testing.

These steps are helping to found out classes from a use case diagram. Some software is used for identification of classes from the use case diagrams, such as Eiffel software. However, best way is manually doing it and at the end testing of classes is must (Larman, 2012).   

All UML diagrams are interlinked and used for better understanding of system requirements. It is a best way for designer to identify classes form the use case diagram. Use cases are like a special work for a module, and actors are the main role of that work. Use case diagrams are showing relationship between actors and use cases. Classes’ identification is the process, which required maximum classes declared in the system but only required classes. Unnecessary declaration of classes create mess-up in the code generation.         

Conclusion:

It is concluded from the last parts of this report that, goal based approach is best way to identification of software classes for designing part of a system. UML is providing different views of a project on the bases of requirements of the system. It is also concluded that, class diagram are used for designing and coding. It is necessary to identify entities of use cases with the help of actors’ relationship and collaboration with use case. Use case-driven process is a part of UML and it is providing a description of project on the bases of requirements and functioning of the system.

Goal-oriented approach

Finally, it is concluded that identification of software classes is a tough work but the help of use case diagram and other things makes it easier. It is just like decoupling of use case diagram.  

Use case diagrams are a part of Unified modeling language (UML). UML provides different diagrams for understanding the requirements of customer for system design. It is an analysis process for taking requirement of the system and put all the information in the graphical form for better understanding and no further issues in requirements. It is a basic need of a project that they give software requirement specification. However, developer is not directly connected to the customers many times. So it is required that visualization of system requirements are in a proper way.     

Class’s identification from the use case diagram is just like decoupling of use cases. On the bases of goal, specification, collaboration, referencing, identification, and specification of use cases classes can be identify. Software testing is also required for that to check all classes are properly selected from use cases. Not all nouns can be converted in the classes. It may create a problem in the end of the project. It is also make some differences, when wrong classes are chosen at the identification step of classes. Sometimes inaccurate requirements are the biggest reason of project failure.  

UML is a best way to finding solution before design phase is started of a software development. It is also having some disadvantages, such as code generation is facing a problem because of so many classes are chosen. Sometimes UML diagrams are so complex for understanding of data and control flow. However, it is a process for understanding SRS and customer needs for that software in a graphical representation.   

References:

Bruegge, B. a. D. A., 2008. Object-Oriented Software Engineering Using UML, Patterns and Java-(Required) (Vol. 2004).. 4 ed. London: Prentice Hall..

Conallen, J., 2012. Building Web applications with UML.. 6 ed. New York: Addison-Wesley Longman Publishing Co., Inc...

Gomaa, H., 2011. Software modeling and design: UML, use cases, patterns, and software architectures.. 2 ed. New York: Cambridge University Press..

Jacobson, . I., 1993. Object-oriented software engineering: a use case driven approach.. 2 ed. New Delhi: Pearson Education India.

Larman, C., 2012. Applying UML and patterns: an introduction to object oriented analysis and design and interative development.. 5 ed. New York: Pearson Education.

Larman, C., 2012. Applying UML and patterns: an introduction to object oriented analysis and design and interative development.. 2nd ed. New Delhi: Pearson Education India.

Liang, Y., 2003. From use cases to classes: a way of building object model with UML. Information and Software technology, 45(2), pp. 83-93.

Liang, Y., 2003. Liang, Y. (2003). From use cases to classes: a way of building object model with UML. Information and Software technology, 45(2), pp. 83-93.

Tsang, . C. H., Leung, Y. . K. & Lau, C. S., 2004. Object-Oriented Technology. New York: McGraw-Hill.

Van Lamsweerde, A., 2009. Requirements engineering: From system goals to UML models to software (Vol. 10).. 2 ed. Chichester: John Wiley & Sons..