Chpt 6

Behavioral Modeling

• Behavioral modeling describes the dynamic aspects of an information system, focusing on how it supports business processes within an organization.
• Object-oriented systems development approaches are often use-case driven, architecture-centric, and iterative/incremental.
• The behavioral model utilizes diagrams from Unified Modeling Language (UML), including activity diagrams, interaction diagrams (sequence diagrams), and behavioral state machines. A CRUDE (create, read, update, delete, execute) matrix is also used to illustrate interactions.
• The goal is to illustrate how objects in a problem domain work together to support use cases, providing an internal view of business processes.
• Different types of behavioral models exist:
  • Type 1: Focuses on the underlying details of a business process, often depicted with interaction diagrams (like activity and sequence diagrams).
  • Type 2: Focuses on changes in underlying data, illustrated by a behavioral state machine.

Interaction Diagrams

• Interaction diagrams are used to model the distribution of system behavior across actors and objects.
• They demonstrate how actors and objects collaborate to achieve use case functionality at an object level.
• Sequence diagrams are a specific type of interaction diagram that visualize the sequence of messages exchanged between objects over time, showing object lifelines and messages.

Use Case Diagram: Campus Housing System

• The diagram illustrates the actors (Apartment Owner, Student) and the system (Campus Housing System) and their interactions, using use case elements like "Add Apartment", "Delete Apartment", and "Search Available Rental Units".

Activity Diagram: Add and Delete Apt.

• The diagram displays the steps involved in adding and deleting apartments. It is a step-by-step representation, visually breaking down the activities, including steps like "Capture Location," "Capture Apartment Identifier," and "Capture Monthly Rent."

Class Diagram

• The diagram shows the relationship between "Apartment Owner" and "Apartment" classes, with a 0..1 to 0..* relationship respectively. This suggests one or zero apartment owners to many apartments.

Sequence Diagram

• The diagrams show the interactions, using lifelines, messages, and execution occurrences (boxes) between the Apartment Owner and Campus Housing Service to complete an "Add Apartment" task, showing how the system functions. This provides a precise sequence of actions.

Sequence Diagram Syntax

• The diagram uses various syntax elements for clarity including:
  • Actors: External entities participating in the interaction.
  • Objects: System participants participating in the sequence.
  • Lifelines: Vertical lines representing the lifetime of an object.
  • Messages: Arrows connecting objects, showing information exchange.
  • Execution occurrences (boxes): Narrow boxes placed above objects/lifelines to indicate message sending and receiving.

CRUDE Analysis

• CRUDE analysis identifies and labels object interactions with the appropriate action type (Create, Read/Reference, Update, Delete, Execute).
• A CRUDE matrix is used to describe how interacting objects support use cases.
• The matrix helps visually represent how objects interact and perform actions.

Making a CRUDE Matrix

• Identify actors and classes as a starting point, and the type of interactions from the activity diagram.
• This allows verification of interactions using the diagrammatic elements.

Behavioral State Machine

• This modeling technique illustrates how objects change over time in response to events.
• It represents the different states an object can be in and the transitions between these states in response to events.
• Objects traverse dynamic states throughout their lifetime.
• It highlights the dynamic nature and possible states of an object over time relating to specific events (such as from admitting to releasing a patient).

Elements of Behavioral State Machine

• States: Distinct conditions an object can exist in at a specific time.
• Events: Changes that lead to transitions between states, in turn changing object properties.
• Transitions: The movement between different object states.
• Guard conditions: Conditions that need to be met for an object to transition into another state.

Balancing Functional and Behavioral

• The sequence diagram should relate to specific use cases.
• Actors and messages in sequence diagrams should correspond with associated entries.
• Complex objects in activity diagrams require corresponding behavioral state machines.

Balancing Structural and Behavioral

• Objects and classes in the CRUDE Matrix and diagrams must directly relate to each other.
• The messages and operations must also correspond to elements.
• Object states should be based on relevant attribute values.