Defining Interface Objects and Actions
15.4.1 Defining Interface Objects and Actions
XRef
An important step in interface design is the definition of interface objects and the
A complete discussion actions that are applied to them. To accomplish this, the user scenario is parsed in of the grammatical
much the same way as processing narratives were parsed in Chapter 12. That is, a parse can be found in
Section 12.6.2. description of a user scenario is written. Nouns (objects) and verbs (actions) are iso- lated to create a list of objects and actions.
Once the objects and actions have been defined and elaborated iteratively, they are categorized by type. Target, source, and application objects are identified. A source object (e.g., a report icon) is dragged and dropped onto a target object (e.g., a printer icon). The implication of this action is to create a hard-copy report. An application object represents application-specific data that is not directly manipulated as part of screen interaction. For example, a mailing list is used to store names for a mailing. The list itself might be sorted, merged, or purged (menu-based actions) but it is not dragged and dropped via user interaction.
5 Goals include a consideration of the usefulness of the task, its effectiveness in accomplishing the overriding business objective, the degree to which the task can be learned quickly, and the degree to which users will be satisfied with the ultimate implementation of the task.
? When the designer is satisfied that all important objects and actions have been
What is
screen layout defined (for one design iteration), screen layout is performed. Like other interface
and how is it
design activities, screen layout is an interactive process in which graphical design
applied?
and placement of icons, definition of descriptive screen text, specification and titling for windows, and definition of major and minor menu items is conducted. If a real world metaphor is appropriate for the application, it is specified at this time and the layout is organized in a manner that complements the metaphor.
To provide a brief illustration of the design steps noted previously, we consider a user scenario for an advanced version of the SafeHome system (discussed in earlier chapters). In the advanced version, SafeHome can be accessed via modem or through the Internet. A PC application allows the homeowner to check the status of the house
from a remote location, reset the SafeHome configuration, arm and disarm the sys- The scenario described
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tem, and (using an extra cost video option 6 ) monitor rooms within the house visu- here is similar to use-
ally. A preliminary user scenario for the interface follows: cases described in Chapter 11.
Scenario: The homeowner wishes to gain access to the SafeHome system installed in his house. Using software operating on a remote PC (e.g., a notebook computer carried by the homeowner while at work or traveling), the homeowner determines the status of the alarm system, arms or disarms the system, reconfigures security zones, and views different rooms within the house via preinstalled video cameras.
To access SafeHome from a remote location, the homeowner provides an identifier and a password. These define levels of access (e.g., all users may not be able to reconfigure the system) and provide security. Once validated, the user (with full access privileges) checks the status of the system and changes status by arming or disarming SafeHome. The user reconfigures the system by displaying a floor plan of the house, viewing each of the secu- rity sensors, displaying each currently configured zone, and modifying zones as required. The user views the interior of the house via strategically placed video cameras. The user can pan and zoom each camera to provide different views of the interior.
Homeowner tasks:
• accesses the SafeHome system •
enters an ID and password to allow remote access •
checks system status
• arms or disarms SafeHome system •
displays floor plan and sensor locations
• displays zones on floor plan •
changes zones on floor plan •
displays video camera locations on floor plan •
selects video camera for viewing •
views video images (4 frames per second) •
pans or zooms the video camera
6 The video option enables the homeowner to place video cameras at key locations throughout a house and peruse the output from a remote location. Big Brother?
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
Objects (boldface) and actions (italics) are extracted from this list of homeowner tasks. The majority of objects noted are application objects. However, video camera loca- tion (a source object) is dragged and dropped onto video camera (a target object) to create a video image (a window with video display).
A preliminary sketch of the screen layout for video monitoring is created (Figure 15.2). To invoke the video image, a video camera location icon, C, located in floor plan displayed in the monitoring window is selected. In this case a camera loca- tion in the living room, LR, is then dragged and dropped onto the video camera icon in the upper left-hand portion of the screen. The video image window appears, dis- playing streaming video from the camera located in the living room (LR). The zoom and pan control slides are used to control the magnification and direction of the video image. To select a view from another camera, the user simply drags and drops a dif- ferent camera location icon into the camera icon in the upper left-hand corner of the screen.
The layout sketch shown would have to be supplemented with an expansion of each menu item within the menu bar, indicating what actions are available for the
Access Configure System Status View Monitoring
SafeHome
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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