The User Interface Design Process
15.2.2 The User Interface Design Process
The design process for user interfaces is iterative and can be represented using a spi- ral model similar to the one discussed in Chapter 2. Referring to Figure 15.1, the user interface design process encompasses four distinct framework activities [MAN97]:
1. User, task, and environment analysis and modeling
2. Interface design
3. Interface construction
4. Interface validation The spiral shown in Figure 15.1 implies that each of these tasks will occur more than
once, with each pass around the spiral representing additional elaboration of require- ments and the resultant design. In most cases, the implementation activity involves prototyping—the only practical way to validate what has been designed.
The initial analysis activity focuses on the profile of the users who will interact “I never design a
with the system. Skill level, business understanding, and general receptiveness to the building before I've
new system are recorded; and different user categories are defined. For each user seen the site and
category, requirements are elicited. In essence, the software engineer attempts to met the people who
understand the system perception (Section 15.2.1) for each class of users. will be using it.”
Once general requirements have been defined, a more detailed task analysis is
Frank Lloyd Wright
conducted. Those tasks that the user performs to accomplish the goals of the system are identified, described, and elaborated (over a number of iterative passes through the spiral). Task analysis is discussed in more detail in Section 15.3.
PA R T T H R E E C O N V E N T I O N A L M E T H O D S F O R S O F T WA R E E N G I N E E R I N G
The analysis of the user environment focuses on the physical work environment. Among the questions to be asked are
• Where will the interface be located physically? • Will the user be sitting, standing, or performing other tasks unrelated to the
interface? • Does the interface hardware accommodate space, light, or noise constraints? • Are there special human factors considerations driven by environmental factors?
The information gathered as part of the analysis activity is used to create an analy- sis model for the interface. Using this model as a basis, the design activity commences.
? The goal of interface design is to define a set of interface objects and actions (and
What is the
goal of user
their screen representations) that enable a user to perform all defined tasks in a man-
interface design?
ner that meets every usability goal defined for the system. Interface design is dis- cussed in more detail in Section 15.4.
The implementation activity normally begins with the creation of a prototype that enables usage scenarios to be evaluated. As the iterative design process continues,
a user interface tool kit (Section 15.5) may be used to complete the construction of the interface. Validation focuses on (1) the ability of the interface to implement every user task correctly, to accommodate all task variations, and to achieve all general user require- ments; (2) the degree to which the interface is easy to use and easy to learn; and (3) the users’ acceptance of the interface as a useful tool in their work.
As we have already noted, the activities described in this section occur iteratively. Therefore, there is no need to attempt to specify every detail (for the analysis or design model) on the first pass. Subsequent passes through the process elaborate task detail, design information, and the operational features of the interface.
Parts
» The Concurrent Development Model
» SUMMARY Software engineering is a discipline that integrates process, methods, and tools for
» PEOPLE In a study published by the IEEE [CUR88], the engineering vice presidents of three
» THE PROCESS The generic phases that characterize the software process—definition, development,
» THE PROJECT In order to manage a successful software project, we must understand what can go
» METRICS IN THE PROCESS AND PROJECT DOMAINS
» Extended Function Point Metrics
» METRICS FOR SOFTWARE QUALITY
» INTEGRATING METRICS WITHIN THE SOFTWARE PROCESS
» METRICS FOR SMALL ORGANIZATIONS
» ESTABLISHING A SOFTWARE METRICS PROGRAM
» Obtaining Information Necessary for Scope
» An Example of LOC-Based Estimation
» QUALITY CONCEPTS 1 It has been said that no two snowflakes are alike. Certainly when we watch snow
» SUMMARY Software quality assurance is an umbrella activity that is applied at each step in the
» R diagram 1.4 <part-of> data model; data model <part-of> design specification;
» SYSTEM MODELING Every computer-based system can be modeled as an information transform using an
» Facilitated Application Specification Techniques
» Data Objects, Attributes, and Relationships
» Entity/Relationship Diagrams
» Hatley and Pirbhai Extensions
» Creating an Entity/Relationship Diagram
» SUMMARY Design is the technical kernel of software engineering. During design, progressive
» Data Modeling, Data Structures, Databases, and the Data Warehouse
» Data Design at the Component Level
» A Brief Taxonomy of Styles and Patterns
» Quantitative Guidance for Architectural Design
» Isolate the transform center by specifying incoming and outgoing
» SUMMARY Software architecture provides a holistic view of the system to be built. It depicts the
» The User Interface Design Process
» Defining Interface Objects and Actions
» D E S I G N E VA L U AT I O N
» Testing for Real-Time Systems
» Organizing for Software Testing
» Criteria for Completion of Testing
» The Transition to a Quantitative View
» The Attributes of Effective Software Metrics
» Architectural Design Metrics
» Component-Level Design Metrics
» SUMMARY Software metrics provide a quantitative way to assess the quality of internal product
» Encapsulation, Inheritance, and Polymorphism
» Identifying Classes and Objects
» The Common Process Framework for OO
» OO Project Metrics and Estimation
» Event Identification with Use-Cases
» SUMMARY Object-oriented analysis methods enable a software engineer to model a problem by
» Partitioning the Analysis Model
» Designing Algorithms and Data Structures
» Program Components and Interfaces
» SUMMARY Object-oriented design translates the OOA model of the real world into an
» Testing Surface Structure and Deep Structure
» Deficiencies of Less Formal Approaches 1
» What Makes Cleanroom Different?
» Design Refinement and Verification
» SUMMARY Cleanroom software engineering is a formal approach to software development that
» Structural Modeling and Structure Points
» Describing Reusable Components
» SUMMARY Component-based software engineering offers inherent benefits in software quality,
» Guidelines for Distributing Application Subsystems
» Middleware and Object Request Broker Architectures
» An Overview of a Design Approach
» Consider expert Web developer will create a complete design, but time and cost can be appropriate
» A Software Reengineering Process Model
» Reverse Engineering to Understand Data
» Forward Engineering for Client/Server Architectures
» SUMMARY Reengineering occurs at two different levels of abstraction. At the business level,
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