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 Model
Ano 2013
Sistemas de Informação
para a Indústria
António Grilo, Izunildo Cabral
Prof. 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 LARG
indicators
Edit system content
Search for LARG
indicators
Extract LARG
indicators
Data analysis
Define formula
Extract LARG
performance
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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