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| changeDate="2007-03-22T05:08:23.977-0800" version="1.0.0"> |
| <mainDescription><h3> Finding Actors </h3>
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| <p> Find the external entities with which the system under development must interact. 
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| Candidates include groups of users who will require help from the system to 
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| perform their tasks and to execute the system's primary or secondary functions, 
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| as well as external hardware, software, and other systems. </p>
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| <p> Define each candidate Actor by naming it and writing a brief description. 
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| Include the Actor's area of responsibility and the goals that the Actor will 
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| attempt to accomplish when using the system. Eliminate Actor candidates who 
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| do not have any goals. For more information on Actors and their properties, 
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| see <a class="elementLinkWithType" href="./../../../openup/guidances/concepts/actor_411726C.html" guid="_zGqO0MDpEduTGJ8i4u8TMw">Concept: Actor</a>. </p>
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| <p> These questions are useful for identifying Actors: </p>
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| <ul>
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| <li>
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| Who will supply, use, or remove information from the system?
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| </li>
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| <li>
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| Who will use the system?
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| </li>
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| <li>
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| Who is interested in a certain feature or service provided by the system?
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| </li>
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| <li>
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| Who will support and maintain the system?
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| </li>
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| <li>
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| What are the system's external resources?
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| </li>
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| <li>
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| What other systems will need to interact with the system under development?
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| </li>
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| </ul>
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| <p> Review the list of stakeholders that you captured in the Vision Statement. 
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| Not all stakeholders will be Actors (meaning, they will not all interact directly 
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| with the system under development), but this list of stakeholders is useful 
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| for identifying candidates for Actors. </p>
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| <h3> Finding likely use cases </h3>
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| <p>
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| The best way to find use cases is to consider what each Actor requires of the system. For each Actor, human or not,
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| ask:
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| </p>
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| <ul>
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| 
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| <li> What are the goals that the Actor will attempt to achieve with the system? 
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| </li>
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| <li>
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| What are the primary tasks that the Actor wants the system to perform?
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| </li>
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| <li>
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| Will the Actor create, store, change, remove, or read data in the system?
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| </li>
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| <li>
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| Will the Actor need to inform the system about sudden external changes?
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| </li>
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| 
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| <li> Does the Actor need to be informed about certain occurrences in the system, 
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| such as unavailability of a network? </li>
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| <li>
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| Will the Actor perform a system startup or shutdown?
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| </li>
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| </ul>
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| <p>
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| Understanding how&nbsp;the target&nbsp;organization works and how this information system might be incorporated into
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| existing operations gives an idea of system's surroundings. That information may reveal other use case candidates.
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| </p>
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| <p> Give a unique name and brief description that clearly describes the goals 
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| for each use case. If the candidate use case does not have goals, ask yourself 
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| why it exists, and then either identify a purpose for it or eliminate the use 
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| case. For more information on use cases and their properties, see <a class="elementLinkWithType" href="./../../../openup/guidances/concepts/use_case_BB199D1B.html" guid="_KudM0NcJEdqz_d2XWoVt6Q">Concept: Use Case</a>. </p>
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| <h3> Outlining use cases </h3>
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| <p> Without going into details, write a first draft of the flow of events of the 
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| use cases identified as high-priority. Initially, write a simple step-by-step 
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| description of the basic flow of the use case. The step-by-step description 
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| is a simple ordered list of interactions between the Actor and the system. For 
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| example, the description of the basic flow of the Withdraw Cash use case of 
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| an automated teller machine (ATM) would be something like this: </p>
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| <ol>
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| <li>
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| The&nbsp;customer inserts a bank card.
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| </li>
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| <li>
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| The system validates the card and prompts the person to enter a personal identification number (PIN).
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| </li>
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| <li>
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| The customer&nbsp;enters a PIN.
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| </li>
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| <li>
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| The system validates the PIN and prompts the customer to select an action.
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| </li>
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| <li>
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| The customer selects Withdraw Cash.
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| </li>
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| <li>
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| The system prompts the customer to choose which account.
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| </li>
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| <li>
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| The customer selects the checking account.
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| </li>
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| <li>
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| The system prompts for an amount.
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| </li>
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| <li>
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| The customer enters the amount to withdraw.
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| </li>
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| 
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| <li> The system validates the amount (assuming sufficient funds), and then issues 
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| cash and a receipt. </li>
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| <li>
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| The customer takes the cash and receipt, and then retrieves the bank card.
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| </li>
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| <li>
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| The use case ends.
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| </li>
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| </ol>
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| <p> As you create this step-by-step description of the basic flow of events, you 
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| may discover alternative and exceptional flows. For example, what happens if 
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| the customer enters an invalid PIN? Capture each alternative flow that you identified 
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| so that you don't forget them. You can fill in the details later. See <a class="elementLinkWithType" href="./../../../openup/guidances/examples/uc_model_evolve_960F136B.html" guid="_t4QdAMNqEdu2IdAIaWZyAw">Example: Evolution of the Use-Case Model</a>&nbsp;for more information on how the use 
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| cases evolve. </p>
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| <h3> Relationships between Actors and use cases </h3>
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| <p> The relationship between Actors and use cases should be captured, or documented&nbsp; 
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| There are several ways to do this. If you are using a use-case model on the 
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| project, you can create use-case diagrams to show how&nbsp;Actors and use cases&nbsp;relate 
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| to each other. See <a href="./../../../openup/guidances/guidelines/uc_model_4C64E97D.html" guid="_0VAUsMlgEdmt3adZL5Dmdw">Guideline: 
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| Use-Case Model</a>&nbsp;for more information. </p>
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| <p>
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| If you are not using a use-case model for the project, make sure that each use case identifies the associated primary
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| and secondary Actors.
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| </p></mainDescription> |
| </org.eclipse.epf.uma:ContentDescription> |
