INSY 5341 C11

Architectural Components

Software and Hardware

Software Components

Data Storage

Data Access Logic - SQL

Application logic

Presentation logic

Data storage

Associated with the object persistence located on the data management

Data Access Logic - SQL 

Associated with the data access and manipulation classes location on the management layer 

Application logic

Located on the problem domain layer

Can be simple or complex, depending on the application

Presentation logic - user interface

Located on the human computer interaction layer

The presentation of information to the user, and the acceptance of the user’s commands

Hardware Components 

Client computers 

Servers 

Connecting Network 

Client computers 

Laptops, desktops, cellphones 

Input/output devices employed by the user and are usually desktop or laptop computers 

Servers

Typically larger computers that are used to store software and hardware that can be accessed by anyone who has permission

Connecting network

Can very in speed from a slow cell phone, to medium speed always on frame relay networks, to fast always on broadband connections such as cable modem, DSL, or T1 circuits, to high speed always on ethernet, T3, or ATM circuits

Server Based Architecture 

One point of control 

Client is a terminal 

Server has functions 

Server has functions

Presentation logic

Application logic

Data access logic

Data storage

Client-Based Architecture

Server is only for storage

Middleware

Thin Client/Fat Server

Fat (thick) Client/ Thin Server

Total cost of ownership

Middleware 

A type of system software designed to translate between different vendors’ software 

Installed on both the client computer and the server computer 

Total cost of ownership

Includes factors other than obvious hardware and software costs

Client-Server Architecture-Server has Data

2-Tiered Architecture

2-Tiered Architecture 

Two sets of computers, clients, servers 

Client-Server Architectures -Client has Presentation Logic

3-Tiered architecture

3-Tiered architecture

Three sets of computers

Client-Server Architectures

N-tiered Architecture

N-tiered Architecture

Uses more than three sets of computers

Characteristics

Cost of infrastructure

Cost of development

Ease of development

Interface capabilities

Control and security

Scalability

Cost of infrastructure

Server-based: Very High

Client-Based: Medium

Client-Server: Low

Cost of development 

Server-based: Medium

Client-based: Low 

Client-Server: High 

Ease of Development

Server-Based: Low

Client-Based: High

Client-Server: Low to medium

Graphical user interface (GUI)

Interface capabilities

Server-based: Low

Client-based: High

Client-Server: High

Control and Security

Server-based: Low

Client-Based: Low

Client-Server: Medium

Scalability 

Refers to the ability to increase or decrease the capacity of the computing infrastructure in response to changing capacity needs  

Cloud Computing

The idea of treating IT as a utility or commodity

Latest approach to support distributed computing in client-server type of architecture where the server is in the cloud and the client is on the desktop

Multitenancy

Multiple users use same underlying hardware + software

Private Cloud

Dedicated to single org (available only to employees)

Public Cloud

Third-party providers multiple customers shared infrastructure (available to general public)

Hybrid 

Both

SaaS

MS 365

PaaS

IDEs (AWS)

The cloud vendor not only provides hardware support to a customer but also provides the customer with either package-based solutions, different services that can be combined to create a solution or the development tools necessary to create custom solutions in the PaaS vendor’s cloud

IaaS 

Hardware + Software (AWS)

Refers to the cloud providing the computing hardware to the firm as a remote service

Virtualization

The idea of treating any computing resource, regardless of where it is located

Virtual memory

Allowed the user/programmer to act as if the amount of main memory in the computer was unlimited

Done by swapping “pages” of main memory out to disk when the content of the pages were not being used and by swapping a page from disk back to main memory when it was needed

Web services 

Basically support connections between different services to form service oriented architectures 

Business process

Services can be combined 

Grid computing

Tends to be the underlying hardware technology that supports the cloud

A large set of networked computers that tend to be geographically dispersed

Ubiquitous

All aspects of life

IOT 

Everyday things connected to computing and internet 

Enchanted Objects

Umbrella, wallet

An everyday object that has a very specializes processor embedded in it that augments the object such that the object seems to be magical

Green IT

Reducing environmental impact of IT

E-Waster

Old computers 

Reuse: Remove Windows and install Linux 

Green Data Centers

Lower electricity Usage

Windfarms, energy compliant computers

Paperless office

Advent of multiuse tablets, such as Apple’s iPad

Considering the cloud and the apps available on the iPad, it is possible not only to create a paperless office but also to have the paperless office effectively be a portable office

Infrastructure Design - Deployment Diagram 

Relationships between the hardware components used in the physical infrastructure of an information system 

Nodes 

Artifacts 

Communication paths 

Nodes

Any piece of hardware in the model

Is computational resource ( a client computer, server, separate network, or individual network device)

Artifacts

Piece of the information system such as software component, database table 

Is a specification of a piece of software or database 

Is labeled by its name 

May contain a stereotype to specifically label the type of artifact 

Communication paths 

Links between nodes of the network 

Represents an association between two nodes 

Allows nodes to exchange messages 

May contain a stereotype to specifically label the type of communication path being represented ( Internet, serial, parallel) 

Network Model

A diagram that shows the major components of the information system and their geographic locations throughout the organization

Non-Functional requirements and physical architecture layer design - Operational Requirements

Specify the operating environments in which the system must perform and how those might change over time

Technical Environment Requirements 

Special hardware, software, and network requirements imposed by business requirements 

System Integrations Requirements

The extent to which the system will operate with other systems

Portability Requirements

The extent to which the system will need to operate in other environments

Maintainability Requirements

Expected business changes to which the system should be able to adapt

Technical environment requirements

Specify the type of hardware and software system on which the system will work

Non-Functional requirements and physical architecture layer design - Performance 

Speed Requirements 

Capacity Requirements 

Availability and Reliability Requirements  

Speed Requirements

The time within which the system must perform its functions

Capacity Requirements

The total and peak number of users and the volume of data expected

Availability and Reliability Requirements 

The extent to which the system will be available to the users and the permissible failure rate due to errors  

Non-Functional Requirements and Physical Architecture Layer Design - Security Requirements

System Value Estimates

Access Control Requirements

Encryption and the Authentication Requirements

Virus Control Requirements

Symmetric

Asymmetric

Certificate Authority

System Value Estimates

Estimated business value of the system and its data

Access Control Requirements 

Limitations on who can access what data 

Access control list 

Capabilities List 

Role based access control

Access Control list

List of users with CRUD access on a file (becomes precondition)

Associated with the asset for which you want to control access

Capabilities List

List of files that a user has CRUD access to

Show that the user had read access to the file 

Encryption and Authentication Requirements

Define what data will be encrypted where and whether authentication will be needed for user access

Virus Control Requirements

Requirements to control the spread of viruses

Asymmetric 

Public key 

Private key 

Certificate Authority

Verisign

Non-Functional requirements and physical architecture layer design - Cultural and Political Requirements

Customization Requirements

Legal Requirements

Customization Requirements

Specification of what aspects of the system can be changed by local users

Legal Requirements

The laws and regulations that impose requirements on the system

Hardware and System Software Specifications

A document that describes what hardware and software are needed to support an application

Alternative Matrix

Benchmark

Parkinson’s Law

Alternative Matrix 

Should include all architectural requirements, both optional and mandatory, and each criterion should be weighted 

Benchmark

Essentially a sample of programs that would be expected to run on the new physical architecture

Parkinson’s Law

Implies that regardless of the users’ real needs, their imagined needs will always fill up whatever capacity the system has

System Integration Requirements 

That require the system to operate with other information systems, either inside or outside the company 

Portability Requirements

Define how the technical operating environments might change over time and how the system must respond

Refer to potential changes in business requirements that drive technical environment changes

Maintainability Requirements

Specify the business requirement changes that can be anticipated

Performance requirements 

Focus on performance issues, such as response time, capacity, and reliability 

Speed requirements

How fast should the system operate?

Response time

How long it takes the system to respond to user request

Capacity requirements 

Attempt to predict how many users the system will have to support, both in total and simultaneously

Are important in understanding the size of the databases, the processing power needed, and so on 

Availability and Reliability Requirements

Focus on the extent to which users can assume that the system will be available for them to use

24/7

Requirement means that users might need help or have questions at any time, and a support desk that is available eight hours a day will not be sufficient support

Mission-Critical System

For an Internet bank that has no brick and mortar branches

If the website crashes, the bank cannot conduct business with its customers

Access Control Matrix

Could combine the access control and capabilities list approaches and require that access is only granted to an IT asset if both the access control list and the capabilities list match

Role-based access controls 

Access is limited by the role that the user is assigned 

Instead of keeping track of the level of access being granted by the individual user, the controls are maintained at the role level

Encryption

Means of disguising information by the use of mathematical algorithms (or formulas)

Can be used to protect data stored in databases or data that are in transit over a network from a database to a computer

Symmetric encryption algorithm

Data Encryption Standard (DES) / Advanced Encryption Standard (AES)

One in which the key used to encrypt to a message is the same as the one used to decrypt it, which means it is essential to protect the key and that a separate key must be used for each person or organization with whom the system shares information

Asymmetric Encryption

Such as public key encryption

One in which the key used to encrypt data is different from the one used to decrypt it

Public Key 

Key used to encrypt data 

Reduces the key-management problem 

Each user has its public key that is used to encrypt messages sent to it 

Private Key 

Key to decrypt it 

Authentication

Digital signatures

Invertible

Public key encryption are invertible meaning that text encrypted with either key can be decrypted by the other

Certificate authority 

A trusted organization that can vouch for the authenticity of the person or organization 

Virus Control Requirements

Addresses the single most common security: viruses