System Analysis
Terms
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- What is the purpose of a use case diagram?
- A use case diagram helps to define the scope of the system by identifying the actor roles that interact with the system and the set of uses or functions provided to those actors.
- What is the difference between a sequence diagram and a collaboration diagram?
- A sequence diagram emphasizes the sequence or order of the messages. A collaboration diagram emphasizes the set of objects that collaborate together to carry out a use case
- What does an actor represent in a use case diagram?
- An actor is the role played by a particular person when that person interacts with the system.
- What does the <<includes>> relationship mean?
- The includes relationship is like a common subroutine. It is a use case that is included in or used by another use case.
- Explain how a collaboration diagram is used to document a use case.
- A use case represents function provided by the system. A collaboration diagram identifies all of the internal objects that must collaborate together to carry out the use case.
- What is the relationship between a use case and a scenario?
- A use case is a general function provided by the system. However, there may be several ways or several different actors that use this use case. A scenario describes the sequence of steps, from the point of view of the external business, of what happens during the flow of a use case
- Describe the syntax of a message descriptor text and explain the meaning of each component
- The part in brackets is a guard condition. A guard condition must evaluate to true in order for the message to be sent. The return-value in a message is similar to a programming concept, which permits the return of information from the message.
- Describe what an object lifeline is and how it is used in a sequence diagram. Contrast an object lifeline to an activation lifeline
- 8An object lifeline represents the period of time for the sequence diagram and the continuance of the particular object in the flow of the sequence. The activation lifeline provides emphasis for the situation when an object exists for only part of a sequence. The beginning and ending of an activation lifeline represents the creation and deletion of an object.
- 9. What are the three guidelines to help determine the source object of a message in a sequence diagram?
- Objects that need service. Objects that have access to input parameters. Objects on the one side of a one-to-many relationship.
- What is the purpose of a statechart diagram? What does a statechart diagram document?
- A statechart diagram describes the life of an individual object in the system. Its purpose is to describe this object lifecycle and identify states and transitions of the object. It also identifies the actions or logic that must be performed by the object.
- Define and explain the concept of a state.
- A state is a semi-permanent condition or state-of-being of an object. It can be interrupted by a transition
- List and describe three different types of pseudostates. Tell the use of each.
- Decision pseudostate splits a path into two possible mutually exclusive paths with an OR condition. A synchronization pseudostate splits a path into two concurrent threads with an AND condition. A begin pseudostate starts a statechart.
- What is meant by dot notation? How is it used?
- Dot notation is a programming construct to identify a particular object. It identifies which object gets a particular message or executes a particular method.
- What is meant by a completion transition? How is it different from a normal transition
- A completion transition is a transition without a trigger or name. It fires automatically when the origin state completes its internal actions.
- Discuss the two ways that concurrency are documented in a statechart diagram. What conditions would cause one to be used instead of the other
- Concurrency can be represented by a composite state with multiple compartments or with two threads initiated with a synchronization bar. A composite state works best when there is a high-level state, such as “on” that has other things going on inside of it. The synchronization bar works best when various paths are completely independent and represent a new activity beginning
- How does an internal transition differ from an external transition? Give some examples of internal transitions
- An internal transition is like an action within a state. It may receive a message or a trigger, but it does not cause the object to change states. An external transition always leaves one state and enters a state
- Describe the relationship between a statechart, interaction diagram, class diagram, and use case diagram
- Every statechart diagram must correspond to exactly only one class on a class diagram. An interaction diagram documents only one use case and must include only objects from classes on the class diagram. Messages on the interaction diagram define the triggers on the transitions in the statechart
- What function does an action-expression serve in a statechart? Where are they located?
- Action expressions are found in states and transitions. They represent the logic that must be performed by the object. Eventually they find their way into the methods of the object class
- List the five diagrams used to define the application requirements from the object oriented prospective.
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a. Class diagram
b. Used Case diagram
c. Collaboration diagram
d. Sequence diagram
e. Statechart diagram - What purpose does the class diagram serve?
- The class diagram defines the components of the system
- The class diagram for the program consists of what two classes?
- Problem domain classes and implementation classes