For example, if the bank changes the business rule to allow the bank balance to be overdrawn by 2000 dollars, the state of the bank account will be redefined with condition that the balance after withdrawal must not be less than $2000 in deficit. The abstraction of the attribute value is a property of the system, rather than a globally applicable rule. You can have more than one Clause, so that if. A sequence diagram is a form of interaction diagram which shows objects as lifelines running down the page, with their interactions over time represented as. A Body partition that performs one or more actions if the Test condition is satisfied. At its simplest, it consists of a Clause containing: A Test partition that evaluates a condition, and. The else InteractionOperator is used to show the sequence that will. A Conditional Structured Activity Node is the modeling equivalent of an 'If-Then-Else' programming construct. This is because the state of the bank account is changed from positive to negative in technical jargon, a transition from the positive state to the negative state is fired. In the UML specification, else is the default sequence in a list of alternative sequences. However, if the account balance would become negative after a withdrawal, the behavior of the withdraw function would be quite different. In such situations, the withdrawals do not affect the abstraction of the attribute values, and hence the gross behavior of the object remains unchanged. The behavior of the withdraw function would be: balance := balance - withdrawAmount provided that the balance after the withdrawal is not less than $0 this is true regardless of how many times you have withdrawn money from the bank. and they are typically used in conjunction with interaction diagrams (usually sequence diagrams).Ĭonsider you have $100,000 in a bank account. State machine diagrams are usually applied to objects but can be applied to any element that has behavior to other entities such as: actors, use cases, methods, subsystems systems and etc. All 3 parts of the transition label are optional. (Just click on a Lifeline if you want to create a self message.) You can change the kind of message by. Guard is the conditional and must evaluate to true in order for the transition to be taken. Drag from a Lifeline and drop on another Lifeline. The transition has a 3-part label in the form of ' trigger-signature guard/activity '. This is not an explicit UML requirement, but a logical deduction considering the. the knowledge of the lifeline that starts the operand (and in some cases knowledge of the enclosing classifier). An object responds differently to the same event depending on what state it is in. 8 On a UML state machine diagram, conditionals are associated with transitions. And since the sequence diagram is made of interactions between its lifelines, the guards should be evaluated based on the available knowledge, i.e. Even UML 1.5 states: The icon provided for a decision is the traditional diamond shape, with one incoming arrow and with two or more outgoing arrows, each labeled by a distinct guard condition with no event trigger. State machine diagram typically are used to describe state-dependent behavior for an object. But showing a picture should comply to the standard.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |