Systems Design: Overview and Activities

Systems Design Overview

• Systems design defines, organizes, and structures components for a final solution blueprint
• Systems design bridges the gap between systems analysis requirements and system implementation
• Systems analysis focuses on "what" is required, while systems design focuses on "how" the system is configured
• Design is a model-building activity where project formality dictates model type, complexity, and depth

Key Terms

• Analysis determines needs, while design determines implementation methods
• Design connects requirements from analysis to implementation
• Models represent the system
• Agile projects require fewer models
• Skipping design leads to suboptimal solutions and rework

Design Activities

• Design activities align with new system components
• Activities include defining the environment, application components, user interface, database, software classes and methods

Key Terms

• The environment considers external systems, communication protocols, and existing technology architecture
• Application components are well-defined software units with specific functions
• User Interface is how users interact with the system
• Database is the data storage and management structure
• Software Classes and Methods involve the detailed design of software components

Environment Design

• Involves communication with external systems and conforming to existing tech architecture
• Communications Include message formats, web and networks, communication protocols, securitymethods, error detection

Application Component Design

• An application component is a well-defined software unit performing specific functions
• Packaging components includes considering scope, size, programming language, and build/buy decisions

Key Terms

• Scope and size define component functions, boundaries, and interfaces
• Determine the accepted programming languages for development
• Decide whether to develop components or purchase them

User Interface Design

• User interfaces impact user productivity
• User interface design includes analysis and design tasks with heavy user involvement
• Current needs require multiple user interfaces for different devices and environments

Key Terms

• User productivity is significantly affected
• User involvement requires significant input from users
• Multiple interfaces support various devices and environments

Database Design

• Information systems require data stored in databases
• Current tech uses Relational Database Management Systems (RDBMS) and involves data model conversion with attention to throughput, response time, and security

Key Terms

• Relational Database Management Systems (RDBMS) are commonly used for data storage
• Data model conversion involves converting the data model to a relational database structure
• Technical issues to address are throughput, response time, and security

Software Classes and Methods

• Detailed design is a model-building activity
• It uses design class diagrams, sequence diagrams, and state-machine diagrams

Key Terms

• Design Class Diagrams display classes, attributes, and relationships
• Sequence Diagrams show interactions between objects over time
• State-Machine Diagrams show object states and transitions

System Controls and Security

• System controls and security protect assets and maintain data integrity
• This includes integrity and security controls

Key Terms

• Integrity controls maintain the integrity of inputs, outputs, data, and programs.
• Security controls protect assets from internal and external threats.

Integrity Controls

• Integrated into application programs and DBMS to ensure appropriate transaction handling, protecting assets like the database

Key Terms

• Integrity controls ensure appropriate transactions are accepted, recorded, and processed correctly, protecting and safeguarding assets.
• Types of controls are Value Limit, Completeness, Data Validation and Field Combination Controls

Input Controls

• Prevent invalid/erroneous data from entering the system

Key Terms

• Value Limit Controls check for reasonable input ranges
• Completeness Controls ensure required data is entered
• Data Validation Controls ensure correct values
• Field Combination Controls ensure data correctness based on inter-field relationships

Output Controls

• Ensure output arrives at the proper destination accurately, currently, and completely

Key Terms

• Guaranteeing output reaches authorized recipients is Proper Destination
• Ensuring output is correct and up-to-date is Accuracy, Currency, and Completeness
• Physical access controls, protecting discarded data, and labels are some examples

Backup and Recovery

• These processes protect data and systems from catastrophes

Key Terms

• Protected assets include databases, hardware, software, and networks
• Store backups both on-site and off-site

Fraud Prevention

• Critical to prevent internal fraud, embezzlement, or loss

Key Terms

• Fraud Triangle consists of opportunity, motive, and rationalization

Security Controls

• Security controls protect against external threats and maintain a stable operating environment.

Key Terms

• Security objectives include a stable operating environment 24/7, protecting information and transactions during transmission.

Access Controls

• Access controls limit access to servers, files, data, and apps

Key Terms

• Authentication identifies users through methods like multifactor authentication
• Access Control List is a list of valid users
• Authorization defines permission levels for each resource
• User types include registered, unauthorized, and privileged users

Data Encryption

• Secures data whether stored or transmitted

Key Terms

• Encryption makes data unrecognizable
• Decryption converts encrypted data back
• Encryption Algorithm is the mathematical transformation
• The encryption key is a long string to produce unique encryptions

Symmetric Encryption

• Symmetric encryption uses the same key to encrypt and decrypt data

Key Terms

• A single key is used for both encryption and decryption

Asymmetric Encryption

• Asymmetric encryption, or Public Key Encryption, uses different keys to encrypt and decrypt data

Key Terms

• Different Keys are separate keys for encryption and decryption.
• Public Key Encryption is another name for asymmetric encryption.

Digital Signatures and Certificates

• A digital signature encrypts a document using a private key
• A digital certificate includes the organization's name and public key certified by a third party

Key Terms

• Digital Signature involves encrypting and decrypting a document with private and public keys
• Digital Certificate includes an organization’s name and public key certified by a third party
• Certifying Authority is the authorized third party performing certification

Secure Transactions

• Secure transactions require protocols for secure network/Internet communication

Key Terms

• SSL (Secure Sockets Layer) is a protocol set for authentication and authorization
• TLS (Transport Layer Security) equates to SSL
• IP Security (IPSec) is an Internet security protocol used for low-level transmissions
• HTTPS (Hypertext Transfer Protocol Secure) transmits webpages securely

Systems Design Summary

• Systems design is modeling to specify system implementation and bridges analysis with implementation

Key Terms

• Analysis involves fact-finding and modeling, while design specifies implementation
• Design functions as a bridge, connecting analysis to implementation

Activities of Systems Design

• Activities include describing the environment, application components, user interface, database, and software classes/methods

Key Terms

• An environment defines system surroundings
• Application components involve designing software units
• The User Interface designs user interaction
• The database designs data storage structure
• Software Classes and Methods involves detailed software design

System Controls and Security Summary

• System controls and security involve integrity and security controls to protect the system

Key Terms

• Integrity controls encompass input and output controls, backup/recovery, and fraud prevention
• Security controls cover access controls, data encryption, digital signatures/certificates and secure transactions

User Interface Design - Key Concepts

• User interface (UI), user experience (UX), and usability are fundamental in systems analysis and design

Key Terms

• User Interface (UI) describes human user's inputs/outputs, the interaction point with the system
• User Experience (UX) covers the entire user interaction with a system, focusing on effectiveness and postive effects
• Usability helps specified users achieve specified goals effectively with efficiency to achieve effectiveness
• User-Centered Design prioritizes user needs throughout the design process, working to focus the emphasis on working users
• Human-Computer Interaction (HCI) studies and designs interaction between people and computers
• Iterative Development allows for repeated testing to ensure continual improvement

UI Design - Metaphors

• Interface design can be aided by relating interface to familiar concepts

Key Terms

• Direct Manipulation represents objects with graphics or icons that can be manipulated
• Desktop Metaphor uses a large workspace & tool icons
• Document Metaphor presents data as paper pages or forms
• Dialog Metaphor involves task completion through conversation via text, voice, or labeled buttons

UI Design - Human Interface

• Specific characteristics will affect usability

Key Terms

• Affordance implies an object’s function through its appearance
• Visibility combined with Feedback provides response to user actions via visible objects on display
• Consistency is achieved through uniform design across platforms and applications
• Continuity includes consistency across releases
• Discoverability helps users uncover hidden options with hovers or pop-ups
• Closure provides end-of-dialog protection of user work, including undo functionality

Principles of Navigation

• Within software applications, navigation principles emphasize readability, clear navigation, and usability

Key Term

• Readability uses readable text for all users
• Clear Navigation is intuitive and simple
• Reverse Navigation lets users go the other way
• Usability and Efficiency implements shortcuts. KISS (Keep It Simple, Stupid)

Storyboarding

• A storyboard shows the design of a user-interface

Key Terms

• Think of the dialog between user and computer
• Base on the flow of activities
• Use natural language to emphasize use
• Create a storyboard or sketch
• Review the storyboard with users

Guidelines for Desktop Applications

• UI design for desktop applications follows precise steps

Key Terms

• Layout and Formatting involves grouping and location purposefully
• Data Entry utilizes the correct choice of controls to minimize errors
• Navigation and Visibility enables scroll bars, resize, maximize, and minimize/close

Guidelines for Mobile Devices

• Specific steps apply to UI on mobile

Key Terms

• Challenges with App Design, Small Screens, touch screens
• Layout and Formatting includes scrolling, resizing, and rotating

Designing Reports

• Focused on printed and on-screen reports

Key Terms

• Details of business reports are found in a Detailed Report
• Summation with reports that can be periodic fall under the class of summary reports
• Details surrounding predetermined values on operating results and transactions are an exception report.
• Used by high-level managers: Executive Reports
• Drilldowns, Linking, and grouping of the data are all considered Electronic Reports
• Visual data includes Multimedia and Graphical Reports

Key Considerations

• UI elements of user design are all considerations

Terms

• Involves user interactions
• Development relies on users
• Takes on forms of metaphors
• UI elements make up
• Principles include the reversal and handling of actions

Transitioning From Analysis

• Discusses a transition from user design with emphasis to use cases

Key Terms

• Used to design use cases
• The menus are typical ways to organize the functions of use cases
• User types
• Multiple users in Subsets

Questions To Considers

• Questions to consider when designing

Key Terms

• Web based?
• Devices
• The OS on which the user interface will run

Object-Oriented Design

• Object-oriented design (OO Design) translates analysis models into design models for coding

Key Terms

• OO-Design building models (OO-Design)
• Iterative SDLC in the Design models
• Simplicity is part of Agile (Agile Approach)
• Creation and instantiations (Instantiations)

Object Oriented design cont...

• Function when invoked (Method)
• Required methods and classes (Object-oriented design)
• Design is based on usage (use case driven)

Cont

• OO has design card and designs class diagrams(Design Classes and the Design Class Diagram)
• CRC Cards are a used technique
• Use cases through multiple paths of progression (Three Paths)

Design Class

• Central OO that has a visual representation (Design Class Diagrams)

Key Terms : Syntax for names, attributes and methods

• Categorization through element characteristics (Stereotype)
• After shutdown the data exists (persistent Class)
• Design identifier, persistent (Entity Class)
• Automation on input (Boundary Class)
• Controller in domain (Controller Class)
• Data Access happens from retrieving data(Data Access Class)

Syntax

• Understanding the syntax is the effective way

Key Terms

• Indicates to those that are accessible (Attribute: Visibility)
• Small Camel (Attribute: Attribute Name)
• Data Types( Attribute: Type Expression)
• The starting (Attribute: Initial Value)
• Examples and Properties(Attribute: Property)
• Notation with elements to invoke (Method Signature)
• Accessible indications (Method signature: Visibility)
• Verty Nound and Small Camel(Method signature: Method name)