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End User data | Objects | Model | Metaphor |
---|---|---|---|
Monitor Key Systems | Systems | Log as consolidated list | View through lens |
Focus on Critical Events | Events | Zoom/wide angle views | |
Keep all Systems in View | |||
For example, in discussing monitoring users often described their work by saying I need the big picture most of the time, but then I need to be able to focus in really quickly on a problem. Combined with the other information about operator responsibilities (e.g., manager statements about central monitoring of many systems) this user statement defines some basic structural issues for the user interface display and navigation mechanisms. There is some form of representation of the managed resources. These resources themselves have certain relationships to one another and to the scope of the operators interest. There are specific notifications of problems, a need to determine what the problem is, and so on. These characteristics constitute the user elements of the conceptual model for how users want to use this application for monitoring. Further, the users description itself suggests a reasonable metaphor for the operation that of a lens onto the managed world with both wide angle and zoom capabilities.Therefore, the general requirements for the interface (expressed in Monitoring Managed Systems --> Viewing Managed topology, Viewing Event Log), the model of the system supporting these requirements, and a metaphor for the operation of that interface can be linked to the detail of the user-centered data.
More generically, the use cases themselves were mined to create a candidate pool of user visible objects and operations. These are the nouns and verbs of the use-case narrative. The user descriptions that underlay the use-cases were examined for specific language and nuance, and together this information was used to create candidate dialogs for display of the objects and menu commands capturing the actions. Specific terms can derive from either standards (e.g., for dialog control) or domain semantics.
In summary, objects are the nominal targets within a direct manipulation interface, but how they are portrayed their context and meaning within the concrete design is shaped by the mediating devices of the conceptual model and metaphor with which they are aligned.
3.2.3. Detailed Screen Design
The objects, models, and metaphors generated from the use-cases were first transformed within Windows 95 Graphical User Interface standards into a paper prototype storyboard. As discussed above, detailed analysis provides a view into the users world in terms of the relevant objects and operations. Models and metaphors are abstractions helping to link the user data to the software system design and implementation. Detailed screen design is the step where specific user interface components must be chosen to express these metaphors and models as they will be used to manipulate the target objects. Figure 3.7 is a copy of a paper prototype screen used in the storyboard for the Monitoring use case. It shows the main application window and is made up of three subwindows within an overall Multiple Document Interface (MDI) application window. The three panes of the child window are the tree view (upper left), the list view (upper right), and the map or icon view (bottom panel). Table 3.2 lists these elements and some brief notes about the rationale for their design.
Figure 3.7 Paper prototype of main window for operator view used within storyboard walkthrough.
GUI Component | Design Rationale | ||
---|---|---|---|
MDI Application window | MDI structure accommodated multiple child windows; windows standard; note both child windows and application itself could be cloned or opened in copies respectively | ||
Tree control | Hierarchical view allowing flexible containment definition for grouping managed resources (by technology, by application etc.); familiar and standard component; easy drag and drop | ||
Icon\map view | Alternative representation of systems allowing use of geographic map backgrounds for added information in icon placement; preferred by subset of users for monitoring | ||
List view | Simple means to show large number of event text descriptions; supported sorting and customization of contained fields; standard control | ||
Linked child window navigation | Selection of a given object in tree or map view automatically filtered events in list to those generated by the specific selected item (or it children if a directory level object); this was indicated in the status bar | ||
Main menu items | Reuse of all standard menu items for generic functions; some customization for view | ||
Viewing topology and viewing event lists were two main ways of monitoring, as reflected in the use case analysis. The icon color status provided quick alerting and the event list provided more information about a specific event (the rows in the list view were also color coded for severity). To support both overall monitoring of a large number of systems and quick focus (wide angle and zooming) whenever any object in the tree or map view was selected the event view would be automatically filtered to show only events for the selected object and its children. In this design the metaphorical focus is implemented with explicit feedback from direct manipulation of the tree, as well as with filtering to reduce the data. Other features helped focus and alerting. For example actions could be defined to produce a pop-up message box when certain events were detected. Figure 3.8 shows a screen capture of an early version of the actual running application.
Figure 3.8 Screen capture of prototype screen for main window.
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