Certification Objective 6.03: Validating Conceptual Design

The final stage of the conceptual design process is validation. Comparing the DFDs with the conceptual database design validates conceptual application design. We must make sure all of the tables relied upon in the DFDs are represented in our database and that we have DFD diagrams for every table in the conceptual database design.

Likewise, conceptual application design diagrams have to be compared with business and user requirement specifications developed earlier on in the design process. We must ensure that every business requirement has at least one procedure diagram associated with it.

Finally, conceptual user interface design is validated with the user through a process called usability testing. In the conceptual design phase, we gathered and analyzed the user profiles and then developed an application “site map” laying out the screens of our application and the order in which users will encounter them. In order to validate this design, we need to go over it with representatives from our user community to ensure nothing was overlooked.

From the Classroom—The Importance of Usability Testing

Usability is the science of designing user interfaces for effectiveness and efficiency from the user's point of view. Usability testing is a process that tests the effectiveness of a user interface using specific methodologies and metrics.

Performing usability testing is important for many applications because it focuses on how the users use the application. There are four main categories of usability issues:

• Navigation

• Screen design and layout

• Terminology

• Consistency with the user's goals

  Usability experts analyze these elements of applications in order to identify those that can be improved. Improving these elements will often lead to improved user experience, which is an important goal in application user interface design.

  —Scott Duffy, MCSD, MCP+SB, SCJP, IBMCD-XML

The process of user interface validation usually involves taking a couple of screens and developing two or three sample layouts. This is not a process of getting colors or graphics approved so much as ensuring that navigational elements and site layout are as efficient as possible. How will users know where they are within the application? How will they get from one section of the application to another? These are all important questions that need to be answered, and the answers should be discussed with the users to ensure that their concerns are addressed early on in the design process.

As you can see, conceptual design is really a process of identifying the components of a system and establishing their relationship to each other. We also must establish program flow (in terms of the user interface) and data flow (in terms of the inputs and outputs of the program).

In the next chapter, we will learn about the steps to creating logical application design. We will cover many topics, from some of the technical considerations that need to be addressed to fully designing the user interface. We will also convert the conceptual data model into a proper logical schema. The entire logical model will then need to be validated as well. Finally, we will see how a proof-of-concept can be used to further validate some of the ideas of our overall application design.