this article series, too, shifting our attention from OMG's UML 1.4 Specification to OMG's Adopted 2.0 Draft Specification of UML (a.k.a. UML 2). I hate to change emphasis from 1.4 to 2.0 in the middle of a series of articles, but the UML 2.0 Draft Specification is an important step forward, and I feel the need to spread the word. There were a couple of reasons that the OMG improved UML. The main reason was that they wanted UML models to be capable of delivering Model Driven Architecture (MDA), which meant that the UML had to function as a more model driven notation. Also, the UML 1.x notation set was at times difficult to apply to larger applications. Furthermore, the notation elements needed to be improved in order to make diagrams more readable. (For example, modeling logical flow in UML 1.x was complicated and at times impossible. Changes to the sequence diagram's notation set in UML 2 have made vast improvements in modeling logic in sequences.) Resources we think you'll like
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Create editable sequence diagram with Rational Software Architect Create editable sequence diagrams with Rational Software Architect What's new in Rational Software Architect 8.5 and Design Manager 4 beta Notice the wording in my statement above: "Adopted 2.0 Draft Specification of UML." It is true that the specification is still in draft status, but the key is that the Draft Specification has been adopted by OMG, a consortium that does not adopt new standards until they become pretty solid. There will be some changes to the specification before UML 2 is completely adopted, but these changes should be minimal. The main changes will be in the internals of UML--involving features typically used by software companies who implement UML tools. The main purpose of this article is to continue our focus on the essential UML diagrams; this month, we take a close look at the sequence diagram. Please note, again, that the examples provided below are based on the new UML 2 specification. The diagram's purpose
The sequence diagram is used primarily to show the interactions between objects in the sequential order that those interactions occur. Much like the class diagram, developers typically think sequence diagrams were meant exclusively for them. However, an organization's business staff can find sequence diagrams useful to communicate how the business currently works by showing how various business objects interact. Besides documenting an organization's current affairs, a business-level sequence diagram can be used as a requirements document to communicate requirements for a future system implementation. During the requirements phase of a project, analysts can take use cases to the next level by providing a more formal level of refinement. When that occurs, use cases are often refined into one or more sequence diagrams. An organization's technical staff can find sequence diagrams useful in documenting how a future system should behave. During the design phase, architects and developers can use the diagram to force out the system's object interactions, thus fleshing out overall system design. One of the primary uses of sequence diagrams is in the transition from requirements expressed as use cases to the next and more formal level of refinement. Use cases are often refined into one or more sequence diagrams. In addition to their use in designing new systems, sequence diagrams can be used to document how objects in an existing (call it "legacy") system currently interact. This documentation is very useful when transitioning a system to another person or organization. Back to top
Since this is the first article in my UML diagram series that is based on UML 2, we need to first discuss an addition to the notation in UML 2 diagrams, namely a notation element called a frame. The frame element is used as a basis for many other diagram elements in UML 2,...
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