PA103 - Object-oriented Methods for Design of Information Systems
Analysis Patterns
© Radek Ošlejšek
Fakulta informatiky MU
oslejsek@fi.muni.cz
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 2Spring 2013
Literature
 Analysis Patterns: Reusable Object
Models
 Author: M. Fowler
 Publisher: Addison-Wesley
Professional
 Copyright: 1996 (2010)
 http://martinfowler.com
 Modeling Principle:
 Models are not right or wrong; they
are more or less useful.
 Patterns are a staring point, not
destination.
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 3Spring 2013
 9 basic pattern collections covering various business domains:
 Accountability – organizational structure and responsibilities
 Observations and Measurements – measured values
 Observations for Corporate Finance – analysis of complex finacial
relationships and results in companies
 Referring to Objects – objects identification
 Inventory and Accounting – cash flow and inventorying
 Planning – schedules and protocols for repetitive plans
 Trading – purchase and selling goods
 Derivative Contracts – prices derived from the prices of other subjects
 Trading Packages – trading for big companies
 Every collection consists of evolutionary sequence of patterns, from very
basic form through combination of various aspects up to complex
solutions
 65 analysis patterns and 21 support patterns in total.
Analysis Patterns of M. Fowler
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 4Spring 2013
Note: Come to Realize that...
=
=
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 5Spring 2013
Lecture 6 / Part 1:
Accountability
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 6Spring 2013
Accountability Patterns
 The concept of accountability applies when a person or organization is
responsible to another.
 Organization structure
 Contracts
 Employment
 ...
 Often used in corporate information systems
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 7Spring 2013
Accountability: List of Patterns
 Party – key concept; supertype of person and organization
 Organization Hierarchies – simple organization hierarchy
 Organization Structure – complex organization structure
 Accountability – key concept; the combination of Party and
Organization Structure
 Accountability Knowledge Level – rules that constrain
accountabilities
 Party Type Generalization – hierarchy of party types
 Hierarchic Accountability – accountabilities for hierarchic and more
complex networks of relationships
 Operating Scopes – responsibilities for parties
 Post – responsibilities delegated to a post, rather than to the person
who occupies it
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 8Spring 2013
Initial model of an address book,Initial model of an address book,
typical result of problem domain modelingtypical result of problem domain modeling
Party: Motivation
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 9Spring 2013
 Often the activities are performed by people, but once in awhile a company
shows up => Party is just a unified name
 Use Party when you have people and organizations in your model and you
see common behavior. However you should also consider this pattern when
you don’t need to distinguish between people and organizations. In this case
it’s useful just to define a party class and not to provide the subtypes.
Party: Pattern
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 10Spring 2013
 … because companies have usually hierarchical organization
structure.
Organization Hierarchies: Motivation
Example: organization structure of international companyExample: organization structure of international company
 Low flexibility: If the organization changes, e.g. Regions are taken out
to provide a flatter structure, then we must alter the model.
 Solution: recursive relationships.
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 11Spring 2013
Organization Hierarchies: Pattern
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 12Spring 2013
Organization Hierarchies: Pattern (cont.)
division
 The danger with the recursive relationship is that it allows a division to be
part of a sales office => subclasses and constraints
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 13Spring 2013
Organization Hierarchies: Discussion
 Q: Having the object diagram on the right, which of the given class diagrams can
instantiate this model?
 A: Both.
division
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 14Spring 2013
Organization Hierarchies: Discussion (cont.)
 Q: How it is easy to change the organization structure?
 A: Without pattern = changes in the model are required. With pattern = new
subclass + new (OCL) rule
division
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 15Spring 2013
Adding Party to Organization Hierarchy
If there isn’t much difference between the
hierarchic association between organizations
and the association between person and
organization so you can pull these
associations up to the supertype.
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 16Spring 2013
Where I already saw it?
 Chemical structure!
 Chemical structure leaded to the use of the Composite GoF pattern
 => Composite pattern is a possible design solution enabling to distinguish
between composite and leaf organizational units.
Where we already saw a similar hierarchical model?
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 17Spring 2013
Example: two independent organizational hierarchies (production vs service)Example: two independent organizational hierarchies (production vs service)
Multiple Organization Hierarchies
 Note: Subtypes of the organization are not shown.
 Problem: If there are many hierarchies, this will soon get out of hand.
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 18Spring 2013
Organization Structure: Pattern
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 19Spring 2013
Organization Structure: Example
 Seller has two shops, in Brno and Prague.
 From the sales point of view, Brno sales office is subordinated to Moravia
division, Prague sale office is subordinated to Bohemia division.
 From the PR point of view, both sale offices are subordinated to the common
central office
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 20Spring 2013
Organization Structure: Properties
 Suitable for multiple organizational hierarchies.
 Adding a new hierarchy = adding a new instance of
OrganizationStructureType
 TimePeriod allows us to record changes in the organization structure over
time.
 Simplifying the object structure puts more emphasis on the rules.
 e.g. „If we have an organization structure whose type is sales
organization and whose child is a division, then the parent must be a
region“
 Constraints to organization structure are expressed by referring to
properties of the organization structure
 => extending the system by adding a new organization structure type
would require changing the rules in the organization structure.
 Solution: Adding a Rule class.
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 21Spring 2013
Organization Structure: Rules
Note: Each addition of a subtype of organization would cause rule changes. Therefore, if we
change the organization structure types rarely but add new subtypes of organization frequently
then this model does not work well. In this case it is better to place the rules on the subtypes of
the organization.
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 22Spring 2013
 Organization Structure shows relationships between organizations. But people have similar
relationships either to organizations or other people as well.
 Each instance of Accountability represents a link between two parties, the
AccountabilityType indicates the nature of the link. This allows you to handle any number of
organizational relationships.
Accountability
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 23Spring 2013
 Create an instance of accountability type for each kind of relationship you need, and
connect together the parties with accountabilities of those types
 You can then use accountabilities to provide similar navigational behavior to what you have
with Organization Hierarchy. The main difference is that much of this behavior is now
qualified by the accountability type. So instead of saying “who are the parents of Boston
Sales” you say “who are the regional parents of Boston Sales”.
Accountability (cont.)
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 24Spring 2013
Accountability Knowledge Level
 If there are many more accountability types than there would be organization structure types
=> introducing knowledge level.
 Connection rules provide a simple yet very flexible form of knowledge level.
 Each accountability type contains a group of connection rules each of which defines one
legal pairing of parent and child party types.
operational level
knowledge level =
configuration of
the operational level
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 25Spring 2013
Accountability Knowledge Level (cont.)
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 26Spring 2013
Accountability: Further Patterns
 Party Type Generalizations
 Adding generalization to party types makes it easier to define the knowledge level
 Hierarchic Accountability
 Improves handling of constrains in organization structures.
 Operating Scopes
 Define the responsibilities that are taken on when an accountability is created.
 Post
 Another party type. Posts are used when accountabilities and scopes are defined by
the post and do not change when the holder of the post changes.
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 27Spring 2013
Lecture 6 / Part 2:
Observations and Measurements
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 28Spring 2013
Observations and Measurements
 Storage and maintenance of quantitative and qualitative data
 Example: height, weight, blood pressure, eyesight. etc. of patients
 Sophisticated alternative to numerical attributes
 Patterns:
 Quantity – values and their units
 Conversion Ratio – conversion ratios between units
 Compound Units – compound units :-) e.g. km/h
 Measurement – measurement and recording of obtained
values
 Observation – general observations and their recording
 Subtyping Observation Concepts
 Protocol – protocols of regular measurements
 ...
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 29Spring 2013
Quantity: Motivation
 The Mars Climate Orbiter was a robotic space probe launched by NASA to study the
Martian climate
 On September 23, 1999, communication with the spacecraft was lost as the spacecraft
went into orbital insertion, due to ground based computer software which produced
output in pound-seconds instead of the metric units of newton-seconds.
 The cost of the mission was $327.6 million
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 30Spring 2013
Question: What means the weight value? kg, g, ounce, something else?
Principle: By combining numbers and their units modeled as objects, we can
describe how to convert quantities with conversion ration, etc.
Quantity: Pattern
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 31Spring 2013
Conversion Ratio: Pattern
 Suitable to convert quantities with conversion ration.
 Problem: How to convert non-linear units, e.g. Celsius to Fahrenheit,
days to months, etc.?
 Solution: Employ the Individual Instance Method pattern, e.g. replace
ConversionRatio with Strategy GoF pattern.
 Problem: How to convert compound units, e.g. km/h to m/s?
 Solution: Next pattern.
 Task: Create exchange table
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 32Spring 2013
Conversion Ratio: Exchange Table
 Task: Create exchange table with the history of rates (design solution)
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 33Spring 2013
Conversion Ratio: Exchange Table with History
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 34Spring 2013
Usage:
acceleration,
Km/h = km hod-1
,
J/cm2
= J cm-2
Task: speed in knots, mile/h, km/h, m/s
Compound Units: Pattern
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 35Spring 2013
knowledge
operational
Measurement: Pattern
 PhenomenonType: things to be measured, e.g. height, weight, blood glucose level, etc.
in a hospital.
 Measurement: concrete measured value
 Person: example of data assigned to the measurement, in this case a patient. Another
attributes could be associated, e.g. who did the measurement, when it was done, where
it was done, etc.
 The operational level has those concepts that change on a day-to-day basis. Their
configuration is constrained by a knowledge level that changes much less frequently.
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 36Spring 2013
Observation: Pattern
 Q: How to record a non-quantitative values, e.g. gender (male/female), blood group
(A+,A-,0, …), etc?
 PhenomenonType: the same as before, e.g. blood group
 Phenomenon: possible values, e.g. A+, A-, 0, …
 CategoryObservation: Concrete observed qualitative value. It is similar to the
measurement but has a general phenomenon instead of quantity.
knowledge
operational
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 37Spring 2013
Observation: Pattern
 Solution:
 PhenomenonType = „oil level“,
 Phenomenon = „over-full“, „OK“, „low“.
 Observation = Instance that links the car to the low phenomenon.
 Task: How to model a low oil level in a car?
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 38Spring 2013
Protocol: Pattern
 Protocol: the method by which the observation were made.
 Example: We can measure a person's body temperature by placing a thermometer in the
mouth, armpit, or rectum.
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 39Spring 2013
Subtyping Observation Concepts: Pattern
 If an observation is made of the presence of the subtype, then all supertypes are also considered to be
present.
 If an observation is made of the absence of a subtype, then that implies neither presence nor absence of
the supertype.
 Example: Diabetes has two subtypes: type I and type II. An observation that type I diabetes is present
for J. Smith implies that diabetes is also present for J. Smith. Absence of type I diabetes does not
mean that J. Smith is not diabetic.
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 40Spring 2013
Obs. and Measurements: Further Patterns
 Dual Time Record:
 Different occurring and recording times/periods of events.
 Ex.: 29.2.2013 doctor records that his patient J. Smith had chest pains six months
ago that lasted for a week.
 Reject Observation
 Observations cannot be deleted if a full audit trail is needed.
 Active Observation, Hypothesis, and Projection
 As observations are recorded, many levels of assurance are given.
 Subtypes of Observations: Hypothesis, Projection, Active Observations, etc.
 Associated Observation
 Ways to record the chain of evidence behind a diagnosis.
 Process Observation
 Behavior models for observations
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 41Spring 2013
Lecture 6 / Part 4:
Observations for Corporate Finance
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 42Spring 2013
Observations for Corporate Finance
 Extension of the Observations and Measurements collection of
pattern focused on (financial) balance of companies.
 Patterns:
 Enterprise Segment – dividing enterprise due to dimensions,
e.g. geographical location, product range, market, industry
sector, etc.
 Measurement Protocol – how measurements can be
calculated from other measurements using formulas that are
instances of model types
 Range – range between two quantities + operations with
ranges
 Phenomenon with Range
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 43Spring 2013
Enterprise Segment: Principle
In some cases we look at the
whole company, but in other
cases we observe only part of the
company, such as 10-11
espresso sales to the government
in the Northeast region.
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 44Spring 2013
Enterprise Segment: Pattern
 Dimension = hierarchy of dimension elements, i.e. the criteria for dividing enterprise
 DimensionElement: Node in the dimension hierarchy, e.g. West Coast area
 GeographicDimensionElement, …: root nodes of dimension hierarchies.
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 45Spring 2013
Lecture 6 / Part 5:
Referring to Objects
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 46Spring 2013
Referring to Objects
 Conceptual thinking about object identity, i.e. references to objects that
humans use.
 Patterns:
 Name – objects identification by names
 Identification Scheme – brings context to objects identification
 Object Merge –
 Object Equivalence –
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 47Spring 2013
Name: Motivation
 The simplest identification for an object is a name.
 The problem is that names are not guaranteed to refer a specific object in
all circumstances.
 e.g. „Masaryk square“
Not all objects have to have a name,
a string can be used as a name for
many objects. Names can be
structured.
Object with aliases,
see also Identification Scheme
String represents a true identifier
(unique ID). Not all strings identify
an object, but to be a true identifier,
it should identify only one.
Example: bar codes.
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 48Spring 2013
Identification Scheme: Pattern
 Many identification schemes for object,
 Examples:
 Identification schemes for banks: SWIFT, sort codes, CHAPS, etc.
 Each hospital assigns a case number to a patient, departments have individual numbers.
 Q: Which schemes do you know to identify a person?
 A: RČ, name, nickname, “my colleague Peter”, etc.
 IdentificationScheme = by ID, by name, by description, …
 Object = concrete person
 String = value, e.g. „790229/1234“
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 49Spring 2013
Object Merge: Pattern
 When (partially) duplicated objects come into existence in a system
 e.g. we realize that our patient is also an out-patient at another department.
 Copy and Replace strategy:
 Copy all the properties of one object over to the another and delete the copied object
 Problem in dealing with references to deleted object.
 Superseding strategy:
 Active object replaces the superseded object. Superseded object delegates all messages to the
active object (references are preserved and we know the history).
superseding strategy
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 50Spring 2013
Object Equivalence: Pattern
 When objects can be considered similar (more-or-less the same, sometimes the same,
etc.).
 Equivalence that is held by certain party.
 Example: Many doctors consider the diseases hepatitis G and hepatitis GBC to be the
same disease, but this is not universal. If a doctor wants a list of patients suffering from
hepatitis G and that doctor is a party on the equivalence, then those patients suffering
from hepatitis GBC are also returned.
PA103: Object-oriented Methods for Design of Information Systems IS © R. Ošlejšek, FI MU 51Spring 2013
Questions?