Week 9 - BUS 362

Architecture design

How a system is distributed across computers and what hardware/software each computer uses

• Objective: assign the software components of the
  information system to hardware devices

Hardware and software specification

Describes the hardware and software needed to support the system

Software system functions

• Data storage: Stores the data

• Data access logic: Get/Access stored data

• Application logic: Performs the actual business processes (DFD, UC, reqs) → Do/rules

• Presentation logic: Displays information to user & accepts user commands (Show/input)

Primary Hardware Components

• Client computers: Devices used by the user to interact with the system

• Servers: multi-user computers used to store software and data

• Network: Connects the computers → to communicate

Client–Server Architectures

Divides processing between client devices and one or more servers

• Client responsible for Presentation logic

• Server handles Data access + Storage

• Application logic varies

• Benefits: Scalable, Compatible, Reliable, most favoured (cost)

Two-Tiered Client-Server

Client devices handle presentation & application logic, & server handles access & storage

• Thick client: Most application logic on client

• Thin client: little application logic on the client → most on server

Three-Tiered Client-Server

Client Device → Application Server (specialized server) → Database Server

n-Tiered Client-Server

Splits the application work into more specialized layers/servers → work-load balancing

• Cons: higher load on network & more difficult server communication

Server-Based Architecture

Server does essentially all the processing & client/terminal does very little → good for security & high transaction volumes

Mobile Application Architecture

• Rich client: most processing on mobile device/client

• Thin web client: most processing on server

• Rich Internet app: browser-based & some client processing for richer User Interface

Mobile Application Options

• Native: built for a specific Operating system & device

• Cross-platform frameworks: one framework → multiple platforms

• Mobile Web app: browser-based & platform independent → limited user experience

Virtualization

Creating a virtual version of a physical device/resource/server

• Server virtualization: 1 physical server → many virtual servers

• Storage virtualization: many storage devices → 1 virtual storage unit

Cloud computing

Computing resources delivered as a service when and where needed

• Advantages: Elastic scale resources up/down with demand, Accessible, customers pay for resources as they’re used

Creating an architecture design

Begins with the nonfunctional requirements

• Operational, Performance, Security, & Cultural and political requirements

Operational requirements

Technical Environment (hardware, software, network), System Integration, Portability, Maintainability (adaptability)

Performance requirements

Speed, Capacity, Availability & reliability

Security requirements

System Value estimates, Access Control, Encryption and Authentication, Virus control

Cultural and political requirements

Multilingual, Customization, Making Unstated Norms Explicit (assumptions for different countries), Legal

Encryption

Disguising information

• Symmetric: same key encrypts & decrypts data

• Asymmetric: different keys encrypt & decrypt data

Hardware/software specification

Document describing the hardware and software needed to support the system/application

• Software needed for each component → Hardware needed → Minimum requirements

• Selection: considers Features, Performance, Legacy, Operating System future strategy, Cost, Political & Vendor performance