Chapter-06
Specifying Operations & Specifying Control
1. What are the two main purpose of operation specification?
Ans.
a) They confirm the user’s view of the logical behavior of a model.
b) They also specify what the designers and programmers must product or meet the user’s requirements.
2. Difference between algorithmic and non-algorithmic technique to operation specification.
Ans. Algorithmic technique
1. An algorithm defines the step-by-step behavior of an operation.
2. An algorithm also specifies the sequence in which the steps are performed.
3. Generally do not prefer in object-oriented development.
4. Describe the internal logic. eg. Activity Diagram.
Non-Algorithmic technique
1. A non-algorithmic approach defines only inputs and results.
2. If does not specifies the sequence.
3. Generally preferred in object-oriented because Non-algorithmic methods of operation specification emphasize encapsulation.
4. Do not describe. eg. Decision table.
3. What are the main component of OCL operation?
Ans. The UML has also a formal language known as Object Constraint Language(OCL). which is intended mainly for specifying general constraints on a model. Most OCL statement consists of the following three components-
a) A context within which the expression is valid (for example, a specified class).
b) A property within the context to which the expression applies(for example and attribute of the specified class).
c) An operation that is applied to the property (for example a mathematical expression that tests the value of the attribute)
4. Define Activity Diagram.
Ans. Activity Diagram:
It is a version of state chart diagram that focuses on a flow of activity driven by internal processing within an object rather than by events that are external to it. In an activity diagram most(or all) states are action states(also called activities) each of which represent the execution of an operation. Activity diagrams can be used to specify the logic or procedurally complex operations.
Specifying Control
1. What do you mean by state chart?
Ans. The state chart is a versatile technique and can be used within and Object-Oriented approach for other purpose than the modeling of object life cycles. A state chart must have at least one initial state.
2. Mention the important link between state-chart and iteration diagram.
Ans. There is an important link between state chart and iteration diagrams. A model of state behavior in a state chart captures all the possible responses of a single object to all the use cases in which it is involved. By contrast a sequence or a collaboration diagram captures the responses of the entire object that are involved in a single use case.
3. What are the main approaches for state-chart?
Ans. The steps involved in the life cycle to state modeling are as follows-
a) Identify major system events.
b) Identify each class that is likely to behave a state dependent response to these events.
c) For each of these classes produce a first-cut state chart by considering the typical life cycle of an instance of the class.
d) Examine the state chart and elaborate to encompass more detailed event behavior.
e) Enhance the state chart to include alternative scenario us.
f) Review the state chart to ensure that is consistent with the use cases. In particular check that the constraints that the state chart implies are appropriate.
g) Iterate through steps d, e & f until the state chart captures the necessary level of detail.
h) Ensure consistency with class diagram and interaction diagrams and other state charts.
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