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| <mainDescription><p align="center">
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| <img height="229" alt="visual modelling" src="./resources/visual.gif" width="447" />
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| </p>
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| <p align="center">
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| Visual modeling raises the level of abstraction
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| </p>
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| <p>
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| Visual modeling is the use of semantically rich, graphical and textual design notations to capture software designs. A
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| notation, such as UML, allows the level of abstraction to be raised, while maintaining rigorous syntax and semantics.
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| In this way, it improves communication in the team as the design is formed and reviewed, allowing the reader to reason
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| about the design, and it provides an unambiguous basis for implementation.
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| </p>
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| <h3>
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| How visual models help
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| </h3>
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| <p>
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| A model is a simplified view of a system. It shows the essentials of the system from a particular perspective and hides
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| the nonessential details. Visual models help you:
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| </p>
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| <ul>
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| <li>
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| Increase understanding of complex systems
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| </li>
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| <li>
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| Explore and compare design alternatives at a low cost
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| </li>
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| <li>
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| Form a foundation for implementation
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| </li>
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| <li>
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| Capture requirements precisely
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| </li>
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| <li>
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| Communicate decisions unambiguously
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| </li>
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| </ul>
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| <h4>
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| Increase understanding of complex systems
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| </h4>
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| <p>
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| The importance of models increases as systems become more complex. For example, you can build a doghouse without
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| blueprints. However, as you progress to building houses and then to skyscrapers, your need for blueprints becomes
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| pronounced.
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| </p>
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| <p>
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| Similarly, a small application built by one person in a few days may be easily understood in its entirety. However, an
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| e-commerce system with tens of thousands of source lines of code (SLOCs) or an air traffic control system with hundreds
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| of thousands of SLOCs can no longer be easily understood by one person. Constructing models allows a developer to focus
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| on the big picture, understand how components interact, and identify fatal flaws.&nbsp;
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| </p>
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| <p>
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| Among the various types of models are these examples:
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| </p>
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| <ul>
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| <li>
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| Use cases to specify behavior unambiguously
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| </li>
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| <li>
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| Class diagrams and data model diagrams to capture design
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| </li>
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| <li>
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| State transition diagrams to model dynamic behavior
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| </li>
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| </ul>
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| <p>
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| Modeling is important because it helps the team visualize, construct, and document the structure and behavior of the
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| system without getting lost in complexity.
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| </p>
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| <h4>
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| Explore and compare design alternatives at a low cost
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| </h4>
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| <p>
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| You can create and modify simple models inexpensively to explore design alternatives. Innovative ideas can be captured
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| and reviewed by other developers before investing in costly code development. When coupled with iterative development,
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| visual modeling helps developers assess design changes and communicate these changes to the entire development team.
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| </p>
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| <h4>
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| Form a foundation for implementation
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| </h4>
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| <p>
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| Today, many projects employ object-oriented programming languages to build reusable, change-tolerant, and stable
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| systems. To get these benefits, it is even more important to use object technology in design.
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| </p>
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| <p>
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| The creation of visual models, whether on paper; around a whiteboard; or in a modeling tool, can help a team to gain
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| agreement on key aspects of the system before investing time in proving their ideas with code. Having a shared model of
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| the system promotes collaboration within the team, encouraging everyone to work towards the same goal.
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| </p>
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| <p>
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| With the support of appropriate tools, you can use a design model to generate an initial code for implementation. This
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| is referred to as <strong>forward engineering</strong> or <strong>code generation</strong>. You can also enhance design
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| models to include enough information to build the system.
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| </p>
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| <p>
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| <strong>Reverse engineering</strong> may also be applied to generate design models from existing implementations. You
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| can use this method to evaluate existing implementations.
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| </p>
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| <p>
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| <strong>Round-trip engineering</strong> combines both forward and reverse engineering techniques to ensure consistent
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| design and code. Combined with an iterative process and the right tools, round-trip engineering allows you to
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| synchronize the design and code during each iteration.
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| </p>
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| <h4>
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| Capture requirements precisely
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| </h4>
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| <p>
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| Before building a system, it's critical to capture the requirements. Specifying the requirements using a precise and
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| unambiguous model helps to ensure that all stakeholders can understand and agree on the requirements.
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| </p>
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| <p>
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| A model that separates the external behavior of the system from the implementation of it helps you focus on the
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| intended use of the system, without getting bogged down in implementation details.
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| </p>
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| <h4>
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| Communicate decisions unambiguously
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| </h4>
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| <p>
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| The Unified Modeling Language (UML) is&nbsp;a consistent notation that can be applied for system engineering, as well
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| as for business engineering. According to these excerpts from the UML specification, a standard notation:
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| </p>
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| <ul>
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| <li>
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| <p>
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| Serves as a language for communicating decisions that are not obvious or cannot be inferred from the code
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| itself.
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| </p>
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| </li>
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| <li>
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| <p>
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| Provides semantics that are rich enough to capture all important strategic and tactical decisions.
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| </p>
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| </li>
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| <li>
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| <p>
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| Offers a form concrete enough for humans to reason [about] and for tools to manipulate.
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| </p>
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| </li>
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| </ul>
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| <p>
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| UML represents the convergence of the best practice in software modeling throughout the object-technology industry. For
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| more information on the UML, see <a class="elementLinkWithUserText" href="./../../../openup/guidances/supportingmaterials/references_6CCF393.html#UML05" guid="_9ToeIB83Edqsvps02rpOOg">[UML05]</a>.
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