Designing System Interfaces, Controls and Security

Only available on StudyMode
  • Download(s) : 232
  • Published : October 11, 2012
Open Document
Text Preview
CMT222/CMM321 SYSTEM ANALYSIS & DESIGN

CHAP 15 DESIGNING SYSTEM INTERFACES, CONTROLS AND SECURITY
Sharifah Mashita Syed Mohamad, PhD School of Computer Sciences Univer siti Sains Malaysia mashita@cs.usm.my

Systems Analysis and Design in a Changing World, 5th Edition

OVERVIEW OF THE CHAPTER
 Differentiates between system interfaces and the user interface  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

Systems Analysis and Design in a Changing World, 5th Edition

2

1. IDENTIFYING SYSTEM INTERFACES
 How do we identify interfaces of the system?  Recap: System vs. User interfaces System interfaces
•I/O requiring minimal human interaction •Inputs captured automatically by some devices such as scanners. •Outputs – reports produced for external agents (other systems)

User interfaces

•I/O requiring human interaction •Customer places an order in a web-based system (Inputs) •Information displayed after the order is made (Outputs)

Systems Analysis and Design in a Changing World, 5th Edition

3

1. IDENTIFYING SYSTEM INTERFACES
 System interfaces are broadly defined as inputs or outputs with minimal or no human intervention. Highly automated input devices such as scanners Inputs that are from data in external databases Outputs to external databases Outputs with minimal HCI Outputs to other systems Real-time connections (both input and output) Systems Analysis and Design in a Changing World, 5th Edition 4

FULL RANGE OF INPUTS AND OUTPUTS

Figure 15-1

Systems Analysis and Design in a Changing World, 5th Edition

5

AN EXAMPLE OF COMMON SYSTEM-TOSYSTEM INTERFACE…..
 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 Many newer systems are using XML to provide a common system-to-system interface It is simple and readable by people E.g. It is used to transfer customer information between systems Systems Analysis and Design in a Changing World, 5th Edition 6

SYSTEM-TO-SYSTEM INTERFACE BASED ON XML

Figure 15-2

Systems Analysis and Design in a Changing World, 5th Edition

7

2. DESIGNING SYSTEM INPUTS
 System developers must focus on these 3 areas when designing inputs for a system: A. Identify devices and mechanisms used to enter input •End users perform some input to the system •But, nowadays, many methods to enter information into a system – scanners & transmitting devices – faster, more efficient and less error prone than user input B. Identify all system inputs and develop list of data content for each •Provide link between design of application software and design of user and system interfaces C. Determine controls and security necessary for each system inputSystems Analysis and Design in a Changing World, 5th Edition

8

2. DESIGNING SYSTEM INPUTS
A. Input devices and mechanisms
 One the first tasks to design system inputs is to evaluate the various alternatives for entering info into the system  The main objective – to ensure error-free data  Some good practices to reduce input errors: 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 Systems Analysis and Design in a Changing World, 5th Edition 9

2. DESIGNING SYSTEM INPUTS
A. Input devices and mechanisms Prevalent Input Devices to Avoid Human Data Entry (to ensure error-free data):        Magnetic card strip readers Bar code readers Optical...
tracking img