Module 11: Designing the Presentation Layer 387
Purpose of the Presentation Layer
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Provide access to system features and functionality
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Human to system (through a user interface)
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System to system (through user services)
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Provide navigation, validation, and error processing
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Communicate with business services
The presentation layer is that part of the business application that provides a
communication mechanism between the user and the business service layer of
the system.
There are two types of users to consider. Human users require an interface
through which they can interact with the system. But other computer systems
can also be considered users. Although these systems do not require a user
interface, they do require an intermediary to the system with which they want to
interact. This intermediary is the user services layer.
Whereas a user interface provides visual and tactile means for humans to
interact with systems, user services provides the navigation, validation, and
error-processing logic. This application logic, designed and implemented as
Component Object Model (COM) components, can be called from either the
user interface or from other systems.
Slide Objective
To introduce students to the
presentation layer and its
purpose.
Lead-in
The presentation layer is
what enables users to
interact with a business
system.
388 Module 11: Designing the Presentation Layer
Duality of the Presentation Layer
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Presentation layer
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User services
$
The application
logic that
provides access
to system
features and
functionality
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User interface
$
What the user
sees and
interacts with
Business
services
Data
services
Data
store
The presentation layer has two parts, the user interface and the user services.
The user interface is how users interact with the system. To users, the user
interface often is the system. If the user interface is not usable, then users say
that the system does not work.
The user services contain the application logic that enables the user interface to
access the business system functionality. The user services are also the entry
points used by external systems to access the features and functionality of the
system.
Slide Objective
To identify the composition
of the presentation layer.
Lead-in
The presentation layer is
composed of two distinct
pieces, each with a different
purpose.
Delivery Tip
This slide relates the
Windows DNA terminology
to the services-based
approach used in this
course.
Module 11: Designing the Presentation Layer 389
Benefits of Presentation Layer Duality
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Separates the form from the functionality
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Facilitates parallel design and development of user
interface and services
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Leverages available design and development skills
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Enables changing the user services logic without
changing the user interface
In the same manner that the COM specification requires separating interface
from implementation, the presentation layer separates form from function by
separating the user interface from the user services.
One of the benefits of this separation is that the user interface can be designed
and developed by a different team than the user services. Additionally, the most
appropriate tools can then be used to develop the user interface and user
services.
The parallelism of design and development enables the optimal use of available
skills. The design of the user interface requires knowledge of usability, and the
design of the user services requires knowledge of COM component
development practices.
Also — like all modular designs — the logic of the user services components can
be changed without changing the user interface.
Slide Objective
To present the basics of the
presentation layer,
especially the separation of
the user interface from user
services.
Lead-in
The division of the
presentation layer into two
parts provides benefits to
the solution designer and
developer.
390 Module 11: Designing the Presentation Layer
Inputs to Presentation Layer Design
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Solution requirements and constraints
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Future-state usage scenarios
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Workflow models
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User profiles
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Task descriptions
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User’s terminology and concepts
The inputs to the design of the presentation layer enable you to create an
effective communication mechanism between users and the business services
layer of the system. The information that you researched, analyzed, and
optimized during the conceptual design phase has provided the inputs for the
design of the presentation layer.
Slide Objective
To connect the presentation
layer design to the outputs
of conceptual design.
Lead-in
The inputs to the
presentation layer design
are typically the outputs of
conceptual design.
Module 11: Designing the Presentation Layer 391
!
!!
!
User Interface Design Basics
In this section
In this section
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Types of User Interfaces
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Goals of User Interface Design
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Designer’s Questions
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Activity 11.1: Experience with User Interfaces
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User Interface Metaphors and Elements
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User Assistance Options
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Characteristics of a Well-Designed
User Interface
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Example: A Well-Designed User Interface
The first area of the presentation layer that you will learn about is the user
interface. In some ways, this interface could be considered the most important
part of the business system because to most users, it is the system. A well-
designed user interface helps drive the success and acceptance of a business
system.
In this section, you will learn about the basics of user interface design,
including the different types of user interfaces, the goals of the design process,
and the characteristics of a good user interface design.
Slide Objective
To introduce the section.
392 Module 11: Designing the Presentation Layer
Types of User Interfaces
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Outputs
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Monitor
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Paper
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Speech
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Inputs
$
Keyboard
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Pointing device
$
Speech
The typical perception of a user interface is what appears on the computer’s
monitor when a user starts a business application. However, the user interface is
really any input or output of the system with which a user interacts.
There are many possible types of user interfaces available, and advancing
technology is constantly increasing the options.
Some inputs and outputs less commonly viewed as user interfaces include:
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Monitors, such as those displaying airline flight arrivals and departures.
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Paper-based output, such as invoices, catalogs, and reports.
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Specialized hardware devices, such as barcode scanners.
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Image-capturing devices, such as scanners, digital cameras, and graphics
tablets.
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Accessibility devices.
When designing the user interface of a system, consider the user needs and
future-state usage scenarios of the solution design.
The focus of this module is on designing graphical user interfaces (GUIs)
to business computer systems. However, the principles and guidelines presented
will apply to any user interface design.
Slide Objective
To present some of the
options for user interfaces.
Lead-in
There are two types of user
interfaces, outputs and
inputs.
Note
Module 11: Designing the Presentation Layer 393
Goals of User Interface Design
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Provide a good user experience
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Focus on user needs and workflow
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Make the system simple to use
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Include users in the design process
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Adhere to user interface guidelines and standards
Designing and developing a user interface that provides a good user experience
requires a knowledge and understanding of the users’ needs and workflow.
Make sure that the design of the interface implements the users’ tasks in a way
that is simple but not simplistic. This aim is accomplished by including users in
all stages of the design and development of the user interface. Finally, adhering
to accepted guidelines and standards, such as those in The Windows Interface
Guidelines for Software Design, will help you succeed in designing a usable
user interface.
Slide Objective
To present a focus for the
user interface design.
Lead-in
The goals of user interface
design are relatively simple,
and clearly focused on the
user.
394 Module 11: Designing the Presentation Layer
Designer’s Questions
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How are users going to interact with the system?
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Does the user interface reflect the concepts and
terminology of the users?
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Are the appropriate metaphors used in the
design of the user interface?
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Do the users have the control they require?
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Can users easily find the features required to
complete common tasks?
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Is the workflow correct and complete?
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Does the interface optimize the workflow of the users?
It might seem obvious that a user interface should be designed for the users and
with their input and feedback. However, often the design of the user interface
seems little more than an afterthought.
The success or failure of an application might depend on the user interface. If
users are unhappy with the interface, they see that as a failure of the system.
Designing and developing a user interface that truly caters to users involves
asking user-focused questions and incorporating the answers in your design.
Slide Objective
To present the questions
that a user interface
designer should ask.
Lead-in
Although it may seem that
user interface design is
trivial, in reality there are
many aspects to consider.
Module 11: Designing the Presentation Layer 395
Activity 11.1: Experience with User Interfaces
User interfaces are more common than you might think. They are not limited to
computer systems, and are a part of anything with which humans need to
interact. Doorknobs, coffee mugs, and televisions all have user interfaces.
In this activity, you will participate in an instructor-lead discussion about
aspects of user interface design in everyday items.
After completing this activity, you will be able to:
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Articulate the aspects of user interface design.
Slide Objective
To introduce the activity.
396 Module 11: Designing the Presentation Layer
User Interface Metaphors and Elements
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Interface metaphors
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Real-world analogies that aid in system design and use
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Help to structure and organize the
functionality of the system
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Reality is the best metaphor!
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Interface elements
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Implement metaphors
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Represent the user’s reality in a different medium
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Enable users to predict system behavior by
building on their existing knowledge
Food
Menu
Metaphors enable a business application to imitate the actual business process
by implementing the representation of the artifacts used by the business.
One of the most obvious metaphors in computer applications is the menu. A
menu in a restaurant provides you with a list of available items from which you
can select what you want. When you try to order something that is not
available, the waitperson informs you of that fact and you make another
selection. A computer menu provides the same type of functionality by
providing a list of available and unavailable options from which you can select
what you want.
Using metaphors that represent the artifacts of the business enable you to
present to the user a reality with which they are familiar, but in a different
medium: the computer screen. The following metaphors are often used in a
business environment:
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Cash registers represent sales in a retail environment.
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World currencies have standard graphical representations.
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Pushpins hold a note in place on a corkboard.
Work with users to identify metaphors and their computer representations or
elements. This approach will make the system more usable by building on
users’ existing knowledge of the business. As a result, users will be able to
work by recognizing familiar elements rather than having to memorize specific
steps.
Slide Objective
To present the concepts of
interface metaphors and
elements, and the
relationship between them.
Lead-in
People frequently use
metaphors to communicate
new ideas. This use of
metaphors is quite evident
in computer applications.
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