6 Part 6: V-Modell Reference Activities

6.3 Activities

6.3.10 System Design

6.3.10.3 Preparing Style Guide for Man-Machine Interface

Purpose

The rules for designing the man-machine interface may either be adopted from already existing specifications or derived from the results of the task analysis.

For the development of a style guide in a first step general design rules shall be defined. Ideally it will be possible to directly adopt a a specified style (for example Windows Style). A style will determine for example colors, shapes, line width and line direction, the use of shadings or the management of user interfaces, their elements, menu commands, pop-up menu or keyboard commands. Specifications will emerge also from organization-specific design guidelines.

For the user interfaces that will have to be developed all relevant elements will be determined on the basis of the »User Tasks Analysis and the requirements. In accordance with the style found, design rules will be assigned to each element. To obtain ergonomic user interfaces, particular attention shall be directed to consistency and clear structuring.

6.3.10.3.1 Determining Design Principles and Alternatives

When developing user interfaces, knowledge and experience shall be considered that make the handling of the system for the user easier and more efficient. An ergonomic user interface will not only be more pleasant to operate (as aresult, it will be accepted by the users), but may also considerably reduce the cost factor working hours when the necessary skills for the system will be acquired and the system will be used; thus it will lead to higher productivity.

Most user interfaces will be strongly influenced by the respective specialty of the associated use case. Standard tasks that will turn up during execution in several user interfaces (for example searching for or entering specialist data) should therefore be mostly be performed the same way unless the specialty will require an exception: For example, in a search dialogue in special cases a conversational guidance that deviates from the standard may be more user-friendly.

For special tasks or utilization contexts it will be thus necessary to find a balance between global consistency and a user interface that will be optimized for the utilization context. In each case identical elements will have to be formed similarily in varying dialogues.

6.3.10.3.2 Identifying and Structuring Operation Elements

The operation elements, such as windows, menus, sliders, buttons or turnbuttons, shall be identified or derived from the user profiles listed in the »User Tasks Analysis, the functions that will have to be supported and the environmental conditions, respectively the hardware and software constraints. These operation elements will have to be structured in accordance with the »Design Principles and Alternatives of the man-machine interface.

6.3.10.3.3 Determining Design Rules

Based on the specified design guidelines, design regulations shall be allocated to all identified operation elements. In addition to the design regulations for operation elements, additional design regulations for dialogues and windows shall be defined. Apart from the pure look ("look and feel") of an operation element, additional design regulations concerning conversational guidance, help mode and window design shall be defined.

Design Rules for Conversational Guidance

The dialogue design will include for example an efficient conversational guidance, an appropriate error handling and the identification and homogeneous design of dialogue types. With regard to a uniform and thus efficient operation, it will be important for systems with a variety of different dialogues that all dialogues will proceed logically to the same pattern or at least to a small number of patterns. This will be guaranteed by the use of dialogue types. A dialogue type will describe the logical sequence of a whole class of dialogues and may be defined by a state transition diagram or by an activity diagram. This will primarily concern the use case dialogues. In this context it will be important that the number of dialogue types that are defined will be as small as possible across the system. One dialogue type and thus also one state transition diagram will be assigned to each use case dialogue.

Design Rules for the Help Mode

The help mode will support the user in carrying out the dialogues. For the development of the help mode some basic design regulations will have to be observed:

• There should be an entry page with a table of contents.
• There should be a search page for help topics.
• There should be a contextual help for individual fields and use case dialogues.
• General information about the application should be available.

Design Rules for Windows

As dialogues will describe the sequences for the interaction with the application, windows will play the role of the interface between user and application. Windows will be composed of operation elements. Design regulations for windows will thus consider less the look of individual operation elements than rather the partition and design of the window area. When defining the design criteria for windows, in particular the following questions will have to be considered:

• How will the operation elements be distributed in the window (layout)?
• Where will the heading bar be and what elements will it contain?
• What functions will be offered in the menu?
• How will the start of the windows and the application take place?
• How will the application support the modification of the window size?
• What types of dialogue windows will be required? Examples will include query dialogues, reference dialogues, selection dialogues and input dialogues.
• Will it be necessary to use a log-in dialogue for log-in?