information systems @ x info425: systems design chapter 9 moving to design part 2

INFORMATION SYSTEMS @ XINFORMATION SYSTEMS @ X

INFO425: Systems DesignINFO425: Systems Design

Chapter 9Chapter 9

Moving to DesignMoving to Design

Part 2Part 2



Design and Integrate the NetworkDesign and Integrate the Network

Network specialists establish network based on Network specialists establish network based on strategic planstrategic plan

Project team typically integrates system into Project team typically integrates system into existing networkexisting network

Technical requirements have to do with Technical requirements have to do with communication via networkscommunication via networks

Technical issues handled by network specialistsTechnical issues handled by network specialists

Reliability, security, throughput, synchronizationReliability, security, throughput, synchronization



Network DesignNetwork Design

Integrate network needs of new system into existing Integrate network needs of new system into existing network infrastructurenetwork infrastructure

Describe processing activity and network connectivity Describe processing activity and network connectivity at each system locationat each system location

Describe communications protocols and middleware Describe communications protocols and middleware that connects layersthat connects layers

Ensure that network capacity is sufficient Ensure that network capacity is sufficient Data size per access type and average Data size per access type and average Peak number of access per minute or hourPeak number of access per minute or hour



Network Diagram for RMO Network Diagram for RMO Customer Support System Customer Support System (Figure 9-14)(Figure 9-14)



Design the Application ArchitectureDesign the Application Architecture

Specify how system use cases are carried outSpecify how system use cases are carried out

Described during system analysis as logical models of Described during system analysis as logical models of system activitiessystem activities

After design alternative is selected, detailed computer After design alternative is selected, detailed computer processing is designed as physical models, such as processing is designed as physical models, such as physical data flow diagrams and structure charts physical data flow diagrams and structure charts (traditional) or interaction diagrams and class diagrams (traditional) or interaction diagrams and class diagrams (OO)(OO)

Approach varies depending on development and Approach varies depending on development and deployment environmentsdeployment environments



Design the User InterfacesDesign the User Interfaces

User interface quality is critical aspect of systemUser interface quality is critical aspect of system

Design of user interface defines how user interacts Design of user interface defines how user interacts with systemwith system

GUI GUI –– windows, dialog boxes, mouse interaction windows, dialog boxes, mouse interaction

Sound, video, voice commandsSound, video, voice commands

To user of system, user interface is the systemTo user of system, user interface is the system

User interface specialistsUser interface specialists –– interface designers, interface designers, usability consultants, human factors engineersusability consultants, human factors engineers



Design the System InterfacesDesign the System Interfaces

System interfaces enable systems to share and System interfaces enable systems to share and exchange informationexchange information

Internal organization systemsInternal organization systems Interfaces with systems outside organizationInterfaces with systems outside organization New system interfaces with package application that organization New system interfaces with package application that organization

has purchased and installedhas purchased and installed

System interfaces can be complexSystem interfaces can be complex Organization needs very specialized technical skills to Organization needs very specialized technical skills to

work on these interfaceswork on these interfaces



Design and Integrate the DatabaseDesign and Integrate the Database

System analysis data model used to create System analysis data model used to create physical database model physical database model

Collection of traditional computer files, relational Collection of traditional computer files, relational databases, and/or object-oriented databasesdatabases, and/or object-oriented databases

Technical requirements, such as response times, Technical requirements, such as response times, determine database performance needsdetermine database performance needs

Design work might involveDesign work might involve Performance tuning, indexingPerformance tuning, indexing NormalizationNormalization Integration between new and existing databasesIntegration between new and existing databases Choosing data access strategy (e.g., static vs. dynamic Choosing data access strategy (e.g., static vs. dynamic

embedded SQL)embedded SQL) Recovery from failure (RAID, mirroring, etc.)Recovery from failure (RAID, mirroring, etc.)



Design and Integrate the System ControlsDesign and Integrate the System Controls

Final design activity to ensure system has Final design activity to ensure system has adequate safeguards (system controls) to protect adequate safeguards (system controls) to protect organizational assetsorganizational assets

Controls are needed for all other design activitiesControls are needed for all other design activities User interface – limit access to authorized usersUser interface – limit access to authorized users System interface – protect from other systemsSystem interface – protect from other systems Application architecture – record transactionsApplication architecture – record transactions Database – protect from software/hardware failureDatabase – protect from software/hardware failure Network design – protect communicationsNetwork design – protect communications



Deployment EnvironmentDeployment Environment

Deployment environment definition bridges analysis and Deployment environment definition bridges analysis and designdesign

HardwareHardware System softwareSystem software Networking Networking

Common deployment environments in which system will Common deployment environments in which system will operateoperate

Related design patterns and architectures for Related design patterns and architectures for application softwareapplication software

Hardware / System Software decisions made in tandem, Hardware / System Software decisions made in tandem, usuallyusually



Single-Computer and Multitier ArchitectureSingle-Computer and Multitier Architecture

Single-computer architectureSingle-computer architecture Mainframe-basedMainframe-based Limited by single machine capacityLimited by single machine capacity

Clustered and multi-computer architectureClustered and multi-computer architecture Group of computers to provide processing and data storage Group of computers to provide processing and data storage

capacitycapacity Cluster acts as a single systemCluster acts as a single system Multicomputer hardware/OS can be less similar than Multicomputer hardware/OS can be less similar than

clusteredclustered



Centralized and Distributed ArchitectureCentralized and Distributed Architecture

Distributes system across several computers and Distributes system across several computers and locationslocations

Relies on communication networks for geographic Relies on communication networks for geographic connectivityconnectivity

Client/server architecture dominant model for Client/server architecture dominant model for distributed computingdistributed computing



Computer NetworkComputer Network

Set of transmission lines, specialized hardware, Set of transmission lines, specialized hardware, and communication protocolsand communication protocols

Enables communication among different users and Enables communication among different users and computer systemscomputer systems

Local area network (LAN)Local area network (LAN) less than one kilometer less than one kilometer long – connects computers within single buildinglong – connects computers within single building

Wide area network (WAN)Wide area network (WAN) over one kilometer long over one kilometer long – implies much greater, global, distances– implies much greater, global, distances

RouterRouter – directs information within network – directs information within network



The Internet, Intranets, and ExtranetsThe Internet, Intranets, and Extranets

InternetInternet – global collection of networks that use – global collection of networks that use TCP/IP networking protocolsTCP/IP networking protocols

IntranetsIntranets Private networks using same TCP/IP protocols as the InternetPrivate networks using same TCP/IP protocols as the Internet Limited to internal users Limited to internal users

ExtranetsExtranets Intranets that have been extended outside the organizationIntranets that have been extended outside the organization



Application ArchitectureApplication Architecture

Complex hardware/networks require more complex Complex hardware/networks require more complex software architecturessoftware architectures

There are commonly used approaches (patterns) There are commonly used approaches (patterns) for application architecturefor application architecture

Client/server architectureClient/server architecture

Three-layer client/server architectureThree-layer client/server architecture

Web services architectureWeb services architecture

Internet and Web-based application architectureInternet and Web-based application architecture



Client/Server ArchitectureClient/Server Architecture

Client/server divides programs into two typesClient/server divides programs into two types ServerServer – manages information system resources or – manages information system resources or

provides well-defined services for clientprovides well-defined services for client ClientClient – communicates with server to request resources – communicates with server to request resources

or servicesor services Advantage – deployment flexibilityAdvantage – deployment flexibility

Location, scalability, maintainabilityLocation, scalability, maintainability

Disadvantage – complexity Disadvantage – complexity Performance, security, and reliabilityPerformance, security, and reliability



Three-Layer Client/Server ArchitectureThree-Layer Client/Server Architecture

Layers can reside on one processor or be Layers can reside on one processor or be distributed to multiple processorsdistributed to multiple processors

Data layerData layer – manages access to stored data in – manages access to stored data in databasesdatabases

Business logic layerBusiness logic layer – implements rules and – implements rules and procedures of business processingprocedures of business processing

View layerView layer – accepts user input and formats and – accepts user input and formats and displays processing resultsdisplays processing results



Three-Layer ArchitectureThree-Layer Architecture



Service Oriented Architecture (SOA)Service Oriented Architecture (SOA)

A service-oriented architecture is a collection of A service-oriented architecture is a collection of services. These services communicate with each services. These services communicate with each other. The communication can involve either other. The communication can involve either simple data passing or it could involve two or more simple data passing or it could involve two or more services coordinating some activity. Some means services coordinating some activity. Some means of connecting services to each other is needed.of connecting services to each other is needed.

A service is a function that is well-defined, self-A service is a function that is well-defined, self-contained, and does not depend on the context or contained, and does not depend on the context or state of other services. state of other services.



Service Oriented Architecture (SOA)Service Oriented Architecture (SOA)

The following figure illustrates a basic service-oriented The following figure illustrates a basic service-oriented architecture. architecture.

Both the sender and receiver know how to Both the sender and receiver know how to communicate, but don’t care about the internal communicate, but don’t care about the internal workings of each otherworkings of each other

Services could be within a company, or you could Services could be within a company, or you could access services from another organization – they just access services from another organization – they just need to agreed on how services will communicateneed to agreed on how services will communicate

Web services: SOA using internet and WWW oriented Web services: SOA using internet and WWW oriented technologies. technologies.

XMLXML .Net.Net JavaJava



SOA - ExampleSOA - Example

Build a supply chain management system out of Build a supply chain management system out of existing ‘components’ existing ‘components’

Another Company’s inventory system (SAP)

Oracle Manufacturing System



Web Services ArchitectureWeb Services Architecture

A client/server architectureA client/server architecture Packages software functionality into server Packages software functionality into server

processes (“services”)processes (“services”) Makes services available to applications via Web Makes services available to applications via Web

protocolsprotocols Web services are available to internal and external Web services are available to internal and external

applications applications Developers can assemble an application using existing Web Developers can assemble an application using existing Web

servicesservices



Internet and Web-Based Application Internet and Web-Based Application ArchitectureArchitecture

Web is complex example of client/server Web is complex example of client/server architecturearchitecture

Can use Web protocols and browsers as Can use Web protocols and browsers as application interfacesapplication interfaces

BenefitsBenefits AccessibilityAccessibility Low-cost communicationLow-cost communication Widely implemented standardsWidely implemented standards



Negative Aspects of Negative Aspects of Internet Application DeliveryInternet Application Delivery

Breaches of securityBreaches of security

Fluctuating reliability of network throughputFluctuating reliability of network throughput

Throughput can be limitedThroughput can be limited

Volatile, changing standardsVolatile, changing standards



MiddlewareMiddleware

Aspect of distributed computing Aspect of distributed computing

Connects parts of an application and enables Connects parts of an application and enables requests and data to pass between themrequests and data to pass between them

Transaction process monitors, object request Transaction process monitors, object request brokers (ORBs), Web services directoriesbrokers (ORBs), Web services directories

Designers reply on standard frameworks and Designers reply on standard frameworks and protocols incorporated into middlewareprotocols incorporated into middleware



Enterprise Application Integration (EAI)Enterprise Application Integration (EAI)

Provides the means to share data between Provides the means to share data between different applications without writing custom different applications without writing custom interfaces.interfaces.

Example:Example: Consider a company that wants to do build an eCommerce Consider a company that wants to do build an eCommerce

portal.portal. Has a number of legacy applications (or even an ERP solution Has a number of legacy applications (or even an ERP solution

in place)in place) Need build the web-based eCommerce infrastructure and link Need build the web-based eCommerce infrastructure and link

with systems that do functions like process orders, manage with systems that do functions like process orders, manage inventory, ship productsinventory, ship products

The company decides to use a major courier service for The company decides to use a major courier service for delivery of products ordered from the web site. delivery of products ordered from the web site.

The company wants an ODS for analysis of transactions taking The company wants an ODS for analysis of transactions taking place on the siteplace on the site



Example Example

eComSite

Courier

Shipping

Inventory

OrderSystem

One solution – custom InterfacesIssues?

ODS



ExampleExample

eComSite

Courier

Shipping

Inventory

OrderSystem

ODSEAI

Alternative – employ EAI solution = Middleware



Advantages of EAIAdvantages of EAI

Cost effectivenessCost effectiveness Time to marketTime to market ScalabilityScalability Ability to deal with complex environmentsAbility to deal with complex environments



SummarySummary

Systems design is process of organizing and Systems design is process of organizing and structuring components of system to allow structuring components of system to allow construction (programming) of new systemconstruction (programming) of new system

Design phase of project consists of activities that Design phase of project consists of activities that relate to design of components of new systemrelate to design of components of new system

Application architecture, user interfaces, system interfaces, Application architecture, user interfaces, system interfaces, databases, network diagrams, system controlsdatabases, network diagrams, system controls

Prototyping may be required to specify any part or all of the Prototyping may be required to specify any part or all of the designdesign



Summary (Summary (continuedcontinued))

Inputs to design activities are diagrams built Inputs to design activities are diagrams built during analysisduring analysis

Outputs of design are also diagrams that describe Outputs of design are also diagrams that describe architecture of new system and detailed logic of architecture of new system and detailed logic of programming componentsprogramming components

Inputs, design activities, and outputs are different Inputs, design activities, and outputs are different depending on whether a structured approach or an depending on whether a structured approach or an object-oriented approach is usedobject-oriented approach is used

Architectural design adapts to development Architectural design adapts to development environment and decomposes design into layersenvironment and decomposes design into layers

information systems @ x info425: systems design chapter 9 moving to design part 2

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