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Lecture

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Department
Information Technology
Course
ITEC 3010
Professor
All Professors
Semester
Winter

Description
Systems Analysis and Design I ITEC3010 – Fall 2010 – Luiz Cysneiros Lecture 10 – Designing Inputs, Outputs and Controls – Nov 23 Overview - This chapter focuses on system interfaces, system outputs, and system controls that do not require much human interaction - Many system interfaces are electronic transmissions or paper outputs to external agents - System developers need to design and implement integrity and security controls to protect system and its data - Outside threats from Internet and e-commerce are growing concern Identifying System Interfaces - System interfaces are broadly defined as inputs or outputs with minimal or no human intervention o Inputs from other systems (messages, EDI) o Highly automated input devices such as scanners o Inputs that are from data in external databases o Outputs to external databases o Outputs to other systems o Real-time connections (both input and output) Extensible Markup Language (XML) - Extension of HTML that embeds self-defined data structures in textual messages - Transaction that contains data fields can be sent with XML codes to define meaning of data fields - XML provides common system-to-system interface - XML is simple and readable by people - Web services is based on XML to send business transactions over Internet Design of System Inputs - Identify devices and mechanisms used to enter input o High-level review of most up-to-date methods to enter data - Identify all system inputs and develop list of data content for each o Provide link between design of application software and design of user and system interfaces - Determine controls and security necessary for each system input Input Devices and Mechanics - Capture data as close to original source as possible - Use electronic devices and automatic entry whenever possible - Avoid human involvement as much as possible - Seek information in electronic form to avoid data re-entry - Validate and correct information at entry point Prevalent Input Devices to Avoid Human Data Entry - Magnetic card strip readers - Bar code readers - Optical character recognition readers and scanners - Radio-frequency identification tags - Touch screens and devices - Electronic pens and writing surfaces - Digitizers, such as digital cameras and digital audio devices Defining the Details of System Inputs - Ensure all data inputs are identified and specified correctly - Can use traditional structured models o Identify automation boundary  Use DFD fragments  Segment by program boundaries o Examine structure charts  Analyze each module and data couple  List individual data fields Using Object-Oriented Models - Identifying user and system inputs with OO approach has same tasks as traditional approach - OO diagrams are used instead of DFDs and structure charts - System sequence diagrams identify each incoming message - Design class diagrams and sequence diagrams identify and describe input parameters and verify characteristics of inputs Determining System Outputs - Determine each type of output - Make list of specific system outputs required based on application design - Specify any necessary controls to protect information provided in output - Design and prototype output layout - Ad hoc reports – designed as needed by user Designing Reports and Statements - Printed versus electronic - Types of output reports o Detailed o Summary o Exception o Executive - Internal versus external - Graphical and multimedia presentation Formatting Reports - What is the objective of report? - Who is the intended audience? - What is the media for presentation? - Avoid information overload - Format considerations include meaningful headings, date of information, date report produced, page numbers Designing Integrity Controls - Mechanisms and procedures built into a system to safeguard it and information contained within - Integrity controls o Built into application and database system to safeguard information - Security controls o Built into operating system and network Objectives of Integrity Controls - Ensure that only appropriate and correct business transactions occur - Ensure that transactions are recorded and processed correctly - Protect and safeguard assets of the organization o Software o Hardware o Information Input Integrity Controls - Used with all input mechanisms - Additional level of verification to help reduce input errors - Common control techniques o Field combination controls o Value limit controls o Completeness controls o Data validation controls Database Integrity Controls - Access controls - Data encryption - Transaction controls - Update controls - Backup and recovery protection Output Integrity Controls - Ensure output arrives at proper destination and is correct, accurate, complete, and current - Destination controls - output is channeled to correct people - Completeness, accuracy, and correctness controls - Appropriate information present in output Interface Design Guidelines - Many interface design guidelines have been published to help system developers o Range from general to very specific rules - System design standards o General principles and rules that must be followed for the interface of any system developed by the organization o Helps to ensure that all user interfaces are usable and all systems developed by the organization have a similar look and feel Visibility and Affordance - Two key principles to ensure good human-computer interaction (Donald Norman) o Visibility  A key principle of HCI that states all controls should be visible (so users know its availability) and provide feedback to indicate the control is responding to the user’s actions  E.g. a button that can be clicked should be visible, and when it is clicked should look like it has been pressed to indicate it is responding o Affordance  A key principle of HCI that states that the appearance of any control should suggest its functionality  e.g. a button affords clicking, a scroll bar affords scrolling, an item in a list affords selecting etc.  Applies to objects on the desktop Implications for Designers - If designers make all controls visible and clear more likely the interface will be usable - Most users are now familiar with Windows user interface and common Windows controls - These principles should also be applied carefully to design of web pages, where there are new types of controls and possible designs of interfaces (not standardized) Eight Golden Rules - Ben Shneiderman proposes eight underlying principles applicable to most interactive systems (and key to usability) o Strive for consistency  Information arranged on forms, the names and arrangement of menus, the size and shape of icons
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