Navigation Design

29.5.2 Navigation Design

Once the WebApp architecture has been established and the components (pages, scripts, applets, and other processing functions) of the architecture have been iden- tified, the designer must define navigation pathways that enable a user to access

WebApp content and services. To accomplish this, the designer must (1) identify the semantics of navigation for different users of the site and (2) define the mechanics (syntax) of achieving the navigation.

A large WebApp will often have a variety of different user roles. For example, roles might be visitor, registered customer, or privileged user. Each of these roles can be asso- ciated with different levels of content access and different services. A visitor may have access to only limited content while a registered customer may have access to a much broader range of information and services. The semantics of navigation for each of these two roles would be different.

The WebApp designer creates a semantic navigation unit (SNU) for each goal asso- ciated with each user role [GNA99]. For example, a registered customer may have six different goals, all resulting in access to different information and services. A SNU is created for each goal. Gnaho and Larcher [GNA99] describe the SNU in the follow- ing way:

A SNU is composed of

The structure of an SNU is composed of a set of navigational sub-structures that we call

a set of navigational

ways of navigating (WoN). A WoN represents the best navigation way or path for users with

substructures called

certain profiles to achieve their desired goal or sub-goal. Therefore, the concept of WoN is

ways of navigating

associated to the concept of User Profile.

(WoN). The SNU represents a specific

The structure of a WoN is made out of a set of relevant navigational nodes (NN) con-

navigational goal for a nected by navigational links, including sometimes other SNUs. That means that SNUs may specific type of user.

themselves be aggregated to form a higher-level SNU, or may be nested to any depth. During the initial stages of navigation design, the WebApp structure (architecture and

components) is assessed to determine one or more WoN for each user goal. As noted,

a WoN identifies navigation nodes (e.g., Web pages) and then links that enable nav- igation between them. The WoN are then organized into SNUs. As design proceeds, the mechanics of each navigation link are identified. Among many possible options are text-based links, icons, buttons and switches, and graph- ical metaphors. The designer must choose navigation links that are appropriate for the content and consistent with the heuristics that lead to high-quality interface design.

In addition to choosing the mechanics of navigation, the designer should also establish appropriate navigation conventions and aids. For example, icons and graph- ical links should look “clickable” by beveling the edges to give the image a three- dimensional look. Audio or visual feedback should be designed to provide the user with an indication that a navigation option has been chosen. For text-based naviga- tion, color should be used to indicate navigation links and to provide an indication of links already traveled. These are but a few of dozens of design conventions that make navigation user-friendly. In addition to conventions, navigation aids such as site maps, tables of contents, indexes, search mechanisms, and dynamic help facil- ities should also be designed at this time.

CHAPTER 29

WEB ENGINEERING