topic: THE USER INTERFACE
The user interface is a point in the system where a human being interacts with the computer.The interface can incorporate hardware, software, procedures and data. The interaction can be direct.For example, a user might access a computer through a screen and keyboard. Printed reports and forms designed to capture data for subsequent input are indirect user interfaces. Note that a well designed user interfaces serves as both connector and a separator, kinking the user to computer and protecting the computer from the user.Before we design the user interfaces we must know the user and understand the task to be performed.Much of the information we need is collected during analysis and high level design. Symbols on the system flowchart identify necessary reports , screens, forms and keyboard operations.On the data flow diagram , floe from sources and to destinations might suggest a need for user interfaces. From data dictionary we can compile list of data elements that are input by and output to users.
The first step in user in interface design is to define the processes, procedures, and other tasks the user must perform. Given a set of tasks, we can design the necessary screens, reports and forms. Next, the dialogues that control the exchange of information between the computer and the user are designed. Finally, a user manual is written to document the various procedures, screens, forms, and dialogues.Much of the information we need to design the user processes is collected during analysis and high level design and thus can be extracted from the logical model , the flowchart, the data dictionary, the requirements specification and other documentation.
At the beginning of the system development life cycle we prepared process descriptios to understand the present system. Near the end of the analysis we studied and documented the processes once againin an effort to define what new system must do.As we near the end cycle and start detailed design, our focus shifts to how each process should be performed.Here the tools must be seme but the intent is different.There are different steps for documenting the processes.
1. List the steps: once we have identified the processes , we can begin design themby listing the steps t5hat should be performed.
2. Identify the input and output data flows: Given the process description, the next step is to identify its input and output data flows.
3. Identify other process attributes:There is more to understanding the process than just listing its steps, inputs and outputs. A sense of the priorties associated with the various process steps can be important in designing a good system.
4.Walk through the process: Given a preliminary design , the next step is to physically walk through the process with the people who will actually do the work. If the process ask the user to do something that impossible or unrealistic , he or she will tell us . Listen to the users , observe their reactions and change the process as necessary.
5. Document more formally: Once the design settled down, document the process more formally using such tools as structured english or a process flowchart . Many other tools are available, follow your own organisation’s internal standards.
forms and reports are integrally related to DFD and ER diagram developed during requirement structuring. A form is business document containing some predefined data and often includes some areas where additional data are to be filled in. Most forms have a stylized format and are usually not in simple rows and columns. A report is a business document containing only predefined data, it is passive document used solely for reading and viewing. A report is only for reading and often contains data about multiple unrelated records in a computer file. On the other hand, a form typicallycontains data from only one record or is, at least, based no one record, such as data about one customer, one order,or one student. The guidelines for the design of forms and reports are very similar.
