Module 1: Model with use cases Examine existing Use Cases, and build a Use Case diagram. Create Use Cases to model the scenario of a customer making a reservation. In this module, begin using Use Cases to model the business scenarios. In TOGAF, this tutorial would be considered part of phase C. Information Systems Architectures. On a Use Case diagram, you model Use Cases that represent the scenarios in your business, and the external actors which interact with those scenarios. The scenarios are described using text or with a sequence of steps. Use Case modeling is considered a problem-driven approach to object-oriented analysis because the designer gives primary consideration to the problem at hand, and not to the relationship between objects (as in the data-driven approach). Modeling with Use Cases can illuminate the need for objects in your system. Once the system has been described in terms of its scenarios, you can examine the text or the steps defining each scenario and determine necessary objects. When you build a new system, you model scenarios that describe the way the business should work. When redesigning an existing system, you choose to model first the scenarios of the current system, and then the scenarios for how the system should work. Use Cases are also used in testing a design. Once the design is complete, you can walk through the steps of the scenarios to determine if the design enables the scenarios to occur as planned. Learn more about the difference between Use Cases and Process Models Where do Use Cases fit with the process and functional modeling in enterprise and business diagrams? They differ in approach. If you are strictly using UML to model your business, you can use Use Cases to create contextual models. This modelling includes: ▪ Context Use Case diagram, which divides the segments of the business into packages. ▪ Use Cases for each business segment package. ▪ UML Activity diagrams to model the process flow of each business Use Case. You may prefer to use the techniques presented in previous tutorials, such as using process chart diagrams to understand business events, process flows, results, and functions that these processes create for contextual and conceptual business modeling. Once you create these diagrams you have the option of using Use Cases as a bridge into object-oriented analysis and design of the business systems. You might create a Use Case corresponding to every low-level process (Elementary Business Process) on the Process Chart diagram, then use the techniques of UML to examine the Use Cases to find objects. Although this introduces a second set of diagrams representing similar ideas (and thus added modeling maintenance, since a change to a business process would have to be represented in both places), it can provide a clear bridge between conceptual business modeling and system modeling with UML. A third alternative would be to skip UML Use Cases entirely, and use the Process Charts to drive the next levels of application design (i.e., creating Sequence and Class diagrams). Learning objectives After completing the lessons in this module you will know how to: ▪ organize a project into packages ▪ model use case scenarios ▪ create a child use case diagram ▪ define a use case using steps ▪ create an includes relationship between use cases ▪ extend a use case ▪ modify properties with USPROPS.TXT ▪ track requirements against use cases Time required This module should take approximately 20 minutes to complete. Prerequisites To complete this module, you will need to have the Tutorial encyclopedia open. If you need directions on how to open prebuilt encyclopedias, or this encyclopedia is not attached to your server, refer to the Introduction section of this module. Lessons in this module Lesson 1.1: Organize a project into packages Organize your project into packages to reflect the different components and stages of development of your business. Lesson 1.2: Model use case scenarios Create a model of a Use Case to show the relationships between actors and packages. Lesson 1.3: Create a child use case diagram Elaborate your Use Case scenario by creating a child Use Case diagram. Lesson 1.4: Define a use case by using steps Define the actors and define a Use Case scenario using steps. Lesson 1.5: Create an includes relationship between use cases Identify what is involved in your Use Case scenario by creating an Includes Relationship sub-scenario. Lesson 1.6: Extend a use case Extend a Use Case to add alternative courses of action to a Use Case scenario. Lesson 1.7: Modify properties with USPROPS.TXT Modify properties in the USRPROPS.TXT file by adding a new definition file and then making the new definition the property of an existing Use Case definition. Lesson 1.8: Track requirements against use cases Attach your Business Requirements, (created in the previous lesson), to the Use Case that satisfies it. Next Lesson 1.1: Organize a project into packages See also UML modeling for information system architecture