Aula 9 21032013 sii-v0

Sistemas de Informação para Indústria© António Grilo 2013Departamento de Engenharia Mecânica e Industrial

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Class 9

UML: Use Case Class Diagram Modelling

Relational ModelAno 2013

Sistemas de Informaçãopara a Indústria

António Grilo, Izunildo CabralProf. Auxiliar FCT-UNL,


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Content

• What is UML?• Types of UML diagrams• Use case modelling• Use case diagram

- Core elements

- Examples• Class diagram (the Entity Relationships, E-R)

- Core elements

- Examples• References


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What is UML?

The UML is a language for the visual modelling of software systems. The reasons for the wide appliance of the UML to modelling software systems (and non-software too), stand in the fact that the UML is only a rich notation independent from the modelling process, which gives possibilities for defining different approaches with the use of the language in different manners and for different purposes (Brdjanin, Maric, & Ieee, 2007).

In UML, five views of a system can be developed:

Use case (external user perspective) Logical (internal system design) Component (architectural constituents) Concurrency (describing mechanisms of co-ordination between independently

processing system parts) Deployment (mapping system parts onto a physical architecture)


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Types of UML diagrams

From UML views a series of diagrams are developed. They are:

Use case Class Object State Sequence Collaboration Activity Component Deployment


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Use case modelling

Use case modelling was first presented as part of the Object-Oriented Software Engineering (OOSE) methodology for software development (Jacobson et al., 1992, 1995).

Use case modelling is a requirement engineering technique that similarly leads to the identification od system activities, but is driven more by the needs of the system’s users than those of the system. In use case modelling, a system is defined by a set of use cases, each describing a system requirement (transaction or function) (Bustard, He, & Wilkie, 2000).


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Use cases and use cases diagram

A use case is a description of system usage and represent a very suitable tool for the identification and specification of system requirements. Use case modelling is concerned with system description in a conceptual way.

Use case diagrams show the interaction of the system with external entities, the so-called actors and describe the functionality of the system as a black box, without revealing its internal structure (Back, Petre, & Paltor, 1999).


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Use cases diagram – core elements

Source: T. A. Pender, 2002


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System - sets the boundary of the system in relation to the actors who use it (outside the system) and the features it must provide (inside the system) (T. A. Pender, 2002).

Actors - Roles adopted by external entities that interact with the system directly (Arlow & Neustadt, 2005). Represent the agents who carry out, or cause to be carried out, the main activities of the system (Bustard, He, & Wilkie, 2000).

Use case - identifies a key feature (requirements) of the system (T. A. Pender, 2002).


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Association - identifies an interaction between actors and Use Cases (T.A. Pender, 2002).

Dependency - identifies a communication relationship between two use cases (T. A. Pender, 2002).

Generalization - defines a relationship between two actors or two use cases where one use case inherits and adds to or overrides the properties of the other (T. A. Pender, 2002).


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Use cases diagram – examples

Consider the example of a Car Driver visiting a Shopping Centre:

Actors: Car Driver and Shopping Centre Information System (IS).

Description of the use case diagram (enter the Car Park): the Car Driver visit the Shopping Centre and attempt to enter in the Park. The Shopping Centre IS will check if space is available, and if so increment the number of Cars present, allow the Car Driver to enter, and record the date and time of entry. If the park is full, the driver wait or drive on.


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Use cases diagram – Car Driver example


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Use cases diagram – login into a Supply Chain IS


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Use cases diagram – search and insert a conference

Source: António, 2008


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Use cases diagram – check suppliers’ inventory level


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Use cases diagram – calculate the SC LARG performance

Super Entity

Insert Entity ID

Introduce LARGindicators

Edit system content

Search for LARGindicators

Extract LARGindicators

Data analysis

Define formula

Extract LARGperformance

System


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Class diagram – the Entity Relationship, E - R

Class diagram (overview)

Classes represent things; relationships represent the connections between things (Vidgen, 2003).

The class diagram illustrates the structural component of the system and clearly identifies the classes, interfaces and their relationships within the system (António, 2008).

Besides representing the concepts, the class diagram allows us to establish the relationships between classes (António, 2008).


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Class diagram – core elements and types of relationships

Source: Haug et al., 2010


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Class diagram – class notation



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Class diagram – relationships description

Assotiation - An association is a structural relationship between things showing that one can navigate from the instances of one class to the instances of another (and possibly vice versa) (Vidgen, 2003).



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Aggregation – is a special type of association used to indicate that the participating objects are not just independent objects that know about each other (T. A. Pender, 2002). Represents the association that exists when an object contains other (António, 2008).



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Composition – is a special way of aggregation, with the restriction that the objects components belong, in fact, the object compound (António, 2008). Is used for aggregations where the life span of the part depends on the life span of the aggregate (T. A. Pender, 2002).



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Class diagram – aggregation vs composition



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Generalization – is the process of organizing the properties of a set of objects that share the same purpose. Generalization relates classes together where each class contains a subset of the elements needed to define a type of object (T. A. Pender, 2002).



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Dependence – the dependence relationships is used to describe situations in which a class depends on the other (António. 2008).



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Class diagram – examples



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Class diagram – examples

Source: Alsaadi, 2006


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References

- Cabral, I. F. (2011). An Information Model for Lean, Agile, Resilient and Green

Supply Chain Management. Master thesis, FCT/UNL.

- Jacobson, I., Christerson, Jonsson, P., & Overgaard, G. (1992). Object Oriented

Software Engineering: A Use Case Driven Approach.

- Jacobson, I., Ericcson, M., & Jacobson, A. (1995). The Object Advantage:

Business Process Re-Engineering With Object Technology.

- Bustard, D. W., He, Z., & Wilkie, F. G. (2000). Linking soft systems and use-

case modelling through scenarios. Interacting with Computers, 13(1), 97-110.

- Brdjanin, D., Maric, S., & Ieee. (2007). An example of use-case-driven

conceptual design of relational database.


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References

- António, N. R. (2008). Um Processo de Modelação de Sistemas Software com

Integração de Especificações Rigorosas. (PhD), Universidade do Minho.

- Pender, T. A. (2002). UML Weekend Crash Course

- Arlow, J., & Neustadt, I. (2005). UML 2 and the Unified Process.

- Back, R. J., Petre, L., & Paltor, I. R. (1999). Analysing UML use cases as

contracts. In R. France & B. Rumpe (Eds.), Uml'99 - the Unified Modeling

Language - Beyond the Standard (Vol. 1723, pp. 518-533). Berlin: Springer-

Verlag Berlin.


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References

- Vidgen, R. (2003). Requirements analysis and UML - Use cases and class

diagrams. [Article]. Computing & Control Engineering Journal, 14(1), 12-17.

- Haug, A., Hvam, L., & Mortensen, N. H. (2010). A layout technique for class

diagrams to be used in product configuration projects. Computers in Industry,

61(5), 409-418. doi: 10.1016/j.compind.2009.10.002.

- Alsaadi, A. (2006). Applying the UML class diagram in the performance analysis.

In A. Horvath & M. Telek (Eds.), Formal Methods and Stochastic Models for

Performance Evaluation (Vol. 4054, pp. 148-165). Berlin: Springer-Verlag Berlin.

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