Summary and highlights for conceptual modeling in software engineering.

1. CONCEPTUAL MODELING
OF INFORMATION
SYSTEMS
Electiva: Ingeniería de
software dirigida por
modelos
Juan Fernando Rojas
Universidad Distrital
Francisco José de Caldas
2014

2. INFORMATION SYSTEM CONCEPTS
AND FUNCTIONS
• Allow wider systems to achieve their objectives.
• Its requirements are determined by the objectives of the
organization.
• Are systems built by an engineer.
• It refers to a designed system that collects, stores, processes and
distributes information about the state of a domain.
• It has 3 main functions: Memory, informative and active.

3. MEMORY FUNCTION
• The objective is maintain an internal representation of the state of
the domain.
• The system tracks the state changes and updates the internal
representation to a given domain.
• It has 2 modes:
Request Autonomous
When the state changes, the user
inform the system about the
change that has ocurred and
request the system to update the
representation of the state.
The system memorizes the state
of the domain without an explicit
request from a user.

4. INFORMATIVE FUNCTION
• It has the function to provide information about the state of a
domain.
• One way to do it is request the informationto the system using a
query, which is answered by the system.
• The informative function does not change the state of the domain.
• It has 2 modes:
Request Autonomous
Users receive information when
they ask to in explicit.
User define a condition for the
state of the domain and order the
system to inform them when this
condition is satisfied.

5. ACTIVE FUNCTION
• The system perfoms actions that modify the state of the domain.
(The system must know the actions it can take, when and how)
• It has 2 modes:
Request Autonomous
Users delegate the systems to
perform an action that may modify
the state of the domain.
Users delegate the systems to
perform an action that may modify
the state of the domain when a
particular condition is satisfied.

6. CONCEPTUAL MODELING
Based in:
 Memory function (particular state to be represented)
 States of domains that varies over time
 Consistent in the representation of states
 The rules to answer queries created by users.

7. THE STRUCTURAL SCHEMA
The state of a given domain consists of a set of relevant properties.
The domain consists of a number of objects and the relationships
between them, which are classified into concepts and is called
conceptual model (It includes a view of how a domain changes).
The set of concepts used in particular domain constitutes a
conceptualization of domain.
An ontology is a concrete view of a particular domain. (Conceptual
schemas)
There must exist a distinction between the conceptual schema of a
domain and the conceptual schema of an information system.

8. THE STRUCTURAL SCHEMA
• The definition of concept: Something formed in our mind through
generalization from certain instances.
• A concept has: Extension, which is the set of its possible instances
and intensión, which is the property shared by all its instances.
• Classification is the operation that associates an object with a
concept.
• Instatiation gives an instance of a concept.
• Entity type is present when the instances of a concept are individual
and identifiable objects.

9. THE STRUCTURAL SCHEMA
• Objects that are instances of an entity type are called entities.
• An entity may be an instance of more tan one entity type.
• The concepts are associative, because the instances are related in 2
or more entities.
• The set of entity and relationship types used to observe the state of
a domain is the conceptualization of the state. (Structural schema)

10. THE INFORMATION BASE
• Is a representation of entities and relationships of a domain, and
their classification into entity and relationship types.
• The classification of an entity into an entity type or a relationship
into a relationship type is called a fact.
• The information base contains facts about a domain.
• Conceptual model could be summarized in: Conceptual schema +
information base.

11. THE BEHAVIORAL SCHEMA
• Specifies the valid changes in the domain state (domain events).
Domain Events:
• Is a change in the state of the domain at time t if the entities or
relationships that exists at t are different from those existing at the
previous point in time.
• A state change consists of a set of 1 or more structural events. The
structural event is an elementary change in the population of an
entity or relationship type.

12. THE BEHAVIORAL SCHEMA
Action Request Events
• Is a request to the information system to perform an action.
• An explicit action request may be external or induced, depending on
whether it is initiated explicitly by a user or by some other action,
respectively.
• The system has to change the information base to reflect the change
in the domain, with the following options:
Query Temporal Generated
Provides information
to the initiator of the
action request.
Is initiated simply by
the passing of time.
Is initiated when a
particular generation
condition is satisfied.

13. THE BEHAVIORAL SCHEMA
Events Types
• An event is an instance of a concept, then, an event type is a concept
whose instances are events.
• All events have a relationship with an entity that is a time instance,
which corresponds to the time at which the event occurs.

14. INTEGRITY CONSTRAINTS
• An information base is valid if the facts it contains are true, and is
complete if it contains all relevant facts.
• An information base has integrity when all its facts are valid and it
contains all relevant facts.
• It’s posible créate mechanisms in a system that automatically
guarantee some level of integrity (Integrity constraints).
• An information base is consistent if it satisfies all the integrity
constraints defined, which must be strongly satisfiables (finite,
nonempty information bases).

15. DERIVATION RULES
• The systems have a certain inference capability. The capability
requires 2 main components: Derivation rules and inference
mechanism.
• A derivation rule is a piece of general domain knowledge that defines
an entity or relationship type in relation to others. Is an expression
that defines how new facts can be inferred from others.
• The inferred mechanism uses derivations rules to infer new
information.

16. THE PRINCIPLE OF NECESSITY FOR
CONCEPTUAL SCHEMAS
• Every information system embodies a conceptual schema. Without a
conceptual schema, a system could no perform any useful function.
• Is not posible to design an information system with no knowledge of
its conceptual schema.
• The principle of necessity:
To develop an information system it is necessary to define its
conceptual schema.

17. THE ABSTRACT ARCHITECTURE OF
AN INFORMATION SYSTEM
• The term architecture is used to refer to the main software components
and their relationships.
• The system architecture depends on several factors: the preferred
architectural style, hardware and software plataform on which it must
opérate.
ISO abstract architecture of an information system

18. THE ABSTRACT ARCHITECTURE OF
AN INFORMATION SYSTEM
• According to the ISO abstract architecture of an information system
diagram: An external schema is a form of representation of the state of the
domain, and an external database is avirtual representation of the state of
the domain in the external schema.
• External schemas also include aspects like the language used to create and
use the queries.
• The external processor is an architectural component that interacts with
users. It receives messages from users, translate them into the language of
the conceptual schema, and forward them to the information processor.
• The information processor is the component that handles the messages
sent by the users and performs any active function that may be delegated
to the system.
• The representation of the state that the system has to maintain internally

19. REQUIREMENTS ENGINEERING
• The step that precedes system design is called requirements engineering.
Those requirements consists in 3 processes: elicitation, specification and
validation.
Elicitation: The future users and designers of the system, analyze their
particular problems and needs and the characteristics of the domain. The
conceptual schema of the existing domain may be created.
Specification: The functional and non functional requirements of the new
system are defined. The functional describes what the system must do,
while the non functional describes the global properties of the system, like a
response time or portability.
Validation: The specifications are checked to ensure that they meet user
requirements.

20. QUALITY OF CONCEPTUAL
SCHEMAS
• Conceptual modeling language must enable to all the domains the relevant
aspects like a structural and behavior aspects.
• A conceptual schema is correct if the knowledge that it defines is true for
the domain and relevant to the functions that the system must perform.
• A conceptual schema is syntactically correct if it respects all rules of the
language in which it is writen. It must be understandable to its relevant
audience. (Simples schemas are easy to understand)
• The property of stability is referred to a flexibility and extensibility. A
conceptual schema is stable if minor changes in the properties of the
domain or in the users requirements don’t entail major changes in the
schema.