Моделирование бизнес-процессов / Моделирование бизнес-процессов / I D E F / compendium

Design documentation—Provides traceability and consistency checking for the developers.

Focus design process on user requirements—Reduces the chance of ad hoc user interface development.

Provide the user with a model of the system—Resulting models can be used for system documentation and user help systems.

Use metaphors from the real world—Such as buttons, menus, etc.

These lists are not meant to be complete, and one can see that many of the goals are conflicting and interdependent. The best thing to do is to strike a balance that best suits the current application and perform user acceptance testing to fine tune the human system interactions. The challenge is to create a well behaved interface that helps the users access and complete their required tasks without getting in the way. The best interfaces do not appear to be interfaces at all.

Basic Concepts in IDEF8

This section describes some of the basic concepts for the method.

Process

A process is an ordered sequence of events. In human-designed systems, the events that constitute a process are designed and ordered to achieve some desired outcome.

Input/Output Item (IOI)

An Input/Output Item is any item which conveys information from the user or to the user. IOIs include, but are not limited to, graphics, text, icons, sound, and tactile feedback. Future versions of IDEF8 should include an IOI dictionary, which is a repository of the information known about a piece of information. This dictionary will include the information about the IOI, for example: (1) Name, (2) Type, (3) Display Method (defaulted by type), (4) Color, (5) Font(s), (6) Icons, (7) Graphics, and (8) Description. The dictionary will also include information about the types or kinds of input items.

Metaphor

Metaphors are models of abstract concepts given in terms of familiar, concrete objects and experiences. This is true if we are using metaphors from our language or metaphors from an interface. Because metaphors are used as models, users have difficulty when a metaphor suggests an incorrect model. Some metaphors are like real world objects (e.g., buttons), while some are unlike the real world but provide a usable model for users (e.g., grabbing a drawing object on the screen is not like grabbing a real world object). IDEF8 includes metaphors in the method and models them as templates to be reused during the HSID.

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The tables in this section are initial attempts to identify possible objects, operations, gestures, and devices that will occur in the design and use of metaphors. The tables are not complete—new devices and new metaphors are created as new technology becomes available.

Table 6. User Gestures and Interactions Table

The following is an attempt to categorize the various ways the user can interact with the system, both physically and logically. For example, users may want to specify either a physical button on an actual device (e.g., a mouse) or a logical button (e.g., an OK button on the screen).

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Table 7. I/O Devices

To support the metaphor design goal, IDEF8 contains a catalog and library of metaphor templates that can be used in the interaction models. These templates are derived from the various metaphors and devices given in the tables.

The use of metaphors is a natural way to convey the model on which the interface operates. Figure 29 illustrates some of the common metaphors used in many systems. The decision to choose one metaphor over another depends on what the behavior of the system should be.

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ON

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Type it out

Select 1

Select 2

Select 3

Figure 29.

Common Metaphors

For example, suppose the situation requires the user to respond to a yes or no query. There are various interaction metaphors that could be used such as a toggle switch, a check box, a list box with ‘yes’ or ‘no’ listed, or even a text entry field requiring the user to type ‘y’,’e’,’s’ or ‘n’,’o’ and press return. The same user interaction scenario can be effected by different metaphorical constructs. All of the examples will support the same user interaction, however some are more appropriate than others.

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IDEF8 uses metaphors to help select the best model of interaction and then instantiate a template that represents the metaphor in detail. The blank template is filled in with the specific requirements of the particular user interaction and added to the detailed HSID model. To illustrate, take the following figures showing an interrupt message box with a message, and two buttons for the two options that the user may take. The system view is described by two process boxes, display dialog and perform actions. These processes are shown to decompose into more detailed processes. The user view is described from the user perspective and a similar structure is shown in the Figure 31.

The Printer is out of Paper

Figure 30.

System View of Out of Paper Dialog Message

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Figure 31.

User View of Out of Paper Dialog Message

To see how the interactions are modeled, Figure 32 contains an interaction diagram that shows how these processes are instantiated over time. The user/system dichotomy is shown in this diagram. The information is conveyed across the interface by the precedence arrow showing the ordering of the processes.

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Figure 32.

Interaction Diagram of Out of Paper Dialog Message

A more detailed example involves the resize box scenario. Anyone who has used a drawing program has had the opportunity to draw a rectangle and resize it. This example breaks down the metaphor into component steps and describes the user and system interactions involved.

Figure 33.

Interaction Diagram of Resize Box Example

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