UML’s StateChart
• FSM, EFSM in UML
• Concurrent states
• Tool support
Example
• Consider the following requirements describing the life cycle
of a bank account entity.
– A bank account is first created by a bank manager. The customer
owning the account has to activate the account within one month.
Otherwise, this account will be automatically cancelled. Once
activated, the customer can use the account to perform bank
transactions. The account becomes blocked for security reasons or if
it is dormant for more than six months. In either case, the customer
is asked to contact the bank. After being blocked for two weeks, if
the customer does not contact the bank, the account will be
cancelled. The customer may cancel the account at any time while it
is active.
• States: created, active, blocked and cancelled.
A bank account is first created by a bank manager. The customer owning the
account has to activate the account within one month. Otherwise, this account
will be automatically cancelled. Once activated, the customer can use the account
to perform bank transactions. The account becomes blocked for security reasons
or if it is dormant for more than six months. In either case, the customer is asked
to contact the bank. After being blocked for two weeks, if the customer does not
contact the bank, the account will be cancelled. The customer may cancel the
account at any time while it is active.
Concurrent states in StateCharts
• Concurrent activities when superstate state
‘created’ is reached
UML’s Activity diagram
• Describe dynamic behavior – sequential and
concurrent flows of activities
• May involve activities spanning more than one
use case
• Action states, activity states and transitions
between them, and swimlanes
• Includes symbols from Petri Nets and
Flowcharts
Example
• Given the following English description of the flow of activities within
a company that receives orders through the internet.
– “Once the order is received by the Customer Service department,
the customer’s credit is checked. If the customer has a bad credit
rating, the order is rejected and closed. Otherwise, an invoice is
prepared and sent to the Finance department for follow up, and at
the same time the order is sent to the Order Fulfillment
department. The Finance department processes the payment once
received and informs the Customer Service department. Also, the
Order Fulfillment department checks if the ordered items are
available. If available, the order is delivered to the customer,
otherwise it is back ordered. In either case, the Customer Service
department is informed.
Once the order is received
by the Customer Service
department, the customer’s
credit is checked. If the
customer has a bad credit
rating, the order is rejected
and closed. Otherwise, an
invoice is prepared and sent
to the Finance department
for follow up, and at the
same time the order is sent
to the Order Fulfillment
department. The Finance
department processes the
payment once received and
informs the Customer
Service department. Also,
the Order Fulfillment
department checks if the
ordered items are available.
If available, the order is
delivered to the customer,
otherwise it is back ordered.
In either case, the Customer
Service department is
informed
Process modeling: Data flow diagram
(DFD)
• Process transforming input data and control
into output data and control
• Bubble representing a process
• Arcs carrying flow of data and control in and
out of a process
• Data store as source and sink of data
• External entities as source and sink of data
Data flow diagram (DFD)
Consistency of process refinement
• Process 2. is refined into 4 subprocesses 2.1 to
2.4
Example
• Consider the following informal requirements.
– ‘An online book ordering system accepts orders from buyers which could
be either human users or software agents. A book order is normally made
after the buyer browses a books catalog. The system checks the
availability of the ordered items in the store inventory and the status of
the buyer in the customer file. If all items are available and the customer
has a good record, the buyer is asked to provide credit card payment and
shipping information. The payment information is then passed to a
payment server to verify their validity. If the payment information is valid,
an online bill and payment confirmation is sent to the buyer. Otherwise,
the buyer is informed of the rejection of the payment information, and
consequently the order. In the meantime, the inventory file, the customer
information file and the orders file are updated. In addition, customer
information including name and shipping address are used to deliver the
ordered items to the buyer”.
Context level diagram
An online book ordering system
accepts orders from buyers
which could be either human
users or software agents. A
book order is normally made
after the buyer browses a books
catalog. The system checks the
availability of the ordered items
in the store inventory and the
status of the buyer in the
customer file. If all items are
available and the customer has
a good record, the buyer is asked to provide credit card payment and shipping
information. The payment information is then passed to a payment server to verify
their validity. If the payment information is valid, an online bill and payment
confirmation is sent to the buyer. Otherwise, the buyer is informed of the rejection
of the payment information, and consequently the order. In the meantime, the
inventory file, the customer information file and the orders file are updated. In
addition, customer information including name and shipping address are used to
deliver the ordered items to the buyer
First refinement
An online book ordering system
accepts orders from buyers
which could be either human
users or software agents. A
book order is normally made
after the buyer browses a books
catalog. The system checks the
availability of the ordered items
in the store inventory and the
status of the buyer in the
customer file. If all items are
available and the customer has
a good record, the buyer is asked to provide credit card payment and shipping
information. The payment information is then passed to a payment server to verify
their validity. If the payment information is valid, an online bill and payment
confirmation is sent to the buyer. Otherwise, the buyer is informed of the rejection
of the payment information, and consequently the order. In the meantime, the
inventory file, the customer information file and the orders file are updated. In
addition, customer information including name and shipping address are used to
deliver the ordered items to the buyer
Refinement of validate order process
An online book ordering system
accepts orders from buyers
which could be either human
users or software agents. A
book order is normally made
after the buyer browses a books
catalog. The system checks the
availability of the ordered items
in the store inventory and the
status of the buyer in the
customer file. If all items are
available and the customer has
a good record, the buyer is asked to provide credit card payment and shipping
information. The payment information is then passed to a payment server to verify
their validity. If the payment information is valid, an online bill and payment
confirmation is sent to the buyer. Otherwise, the buyer is informed of the rejection
of the payment information, and consequently the order. In the meantime, the
inventory file, the customer information file and the orders file are updated. In
addition, customer information including name and shipping address are used to
deliver the ordered items to the buyer
Structured English, Decision Table and
Decision Tree
• To describe a process
• Typically used for a stateless (no internal
states, no memory of previous inputs) process
• Pseudocode, structured english
Decision table
• Rows in the table are of two types: condition rows and action rows.
• A column represents a combination of condition outcomes and the
corresponding actions to take.
– also referred to as a rule.
• A complete decision table specifies one rule for each combination of
the condition outcomes.
– For example, if we have three independent binary conditions, the number of
combinations or rules must be 23 = 8.
• A decision table contains redundancy, it there exists two columns
that are equivalent.
• A decision table is ambiguous or contradictory if for the same
combination of condition outcomes, the specified actions are
different.
Data modeling
• Chen’s entity relationship diagram (ERD)
• Entities representing objects to be saved in
permanent stores
– Attributes for each entity
• Relationships linking entities (binary, ternary,
.. Relationships)
• Cardinality of the relationship: 1 to 1, 1 to
many, and many to many
Data dictionary
• Explaining the data items in a DFD or ERD
• For example in level 0 (first refinement) DFD of
Figure 4.21:
–
–
–
–
reply = Msg1 or Msg2 or Msg3 in the data dictionary.
Msg1 = ‘Unable to accept your order at this moment’
Msg2 = ‘Unavailable items at this moment’
Msg3 = ‘Thank you for your order – Please proceed
with payment’.
Object oriented analysis (OOA)
• Based on the identification of problem-domain
objects, their attributes and operations
• Identification of relationships among objects
• Object states and transitions among them
• Description of the interactions among objects
• Textual analysis of requirements: nouns and
verbs
What can be an problem domain
Object?
• Entities that have more than one attribute
• Entities that need to be retained in permanent storage for future use
• External entities that produce information to be used or consumed
by the system, or that consume information generated or produced
by the system
• Events or actions that occur during the system’s operations
• Roles played by people interacting with the system
• Organizational units and places that are important in the problem
domain such as flight crew team or airport
• Logical items such as flight reports and documents
• Composite physical items such as an airplane or a personal computer
Three types of solution domain objects
• Entity objects: to remain in permanent store
for future use and reference
• Interface objects: forms, GUI components
that are used but are not saved (transient
objects)
• Control objects: encoding the business
procedure or control flow (one per use case?)
Example
• Let us analyze the following English text providing a partial
description of the requirements for a Proposal Evaluation System
(PES).
“PES allows different types of users to perform their functions. The
three types of users are Evaluators, Administrators and Proposal
Submitters. Users must first logon successfully to the system to be
able to work. Submitters will submit their proposals. An Administrator
will perform a basic evaluation of the proposal before assigning it to
an Evaluator. The basic evaluation checks whether the Submitter has
already submitted another pending proposal. If so the submission
fails the check. In addition, the Submitter cannot have more than two
accepted proposals to pass the basic check. If the proposal does not
pass the basic check, the Submitter is informed and the refusal is
logged in history.
Example
• An Administrator sends an email to the Evaluator once she/he is
assigned to a proposal. The Evaluator will evaluate the
proposal and will send his/her evaluation to the Administrator
either by email or by filling a form on the internet. The
Administrator will inform the Submitter of the result of the
evaluation. At this point the proposal evaluation process is
considered done”.
Object relationships:
inheritance
(generalization/specialization,
is_a)
Composition
relationship
(includes, made of)
Associations and roles