1. Chapter 9
Moving to Design
Part 2

2. Design and Integrate the Network
Network specialists establish network based on strategic plan
Project team typically integrates system into existing network
Technical requirements have to do with communication via networks
Technical issues handled by network specialists
Reliability, security, throughput, synchronization

3. Network Design
Integrate network needs of new system into existing network infrastructure
Describe processing activity and network connectivity at each system location
Describe communications protocols and middleware that connects layers
Ensure that network capacity is sufficient
Data size per access type and average
Peak number of access per minute or hour

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

5. Design the Application Architecture
Specify how system use cases are carried out
Described during system analysis as logical models of system activities
After design alternative is selected, detailed computer processing is designed as physical models, such as physical data flow diagrams and structure charts (traditional) or interaction diagrams and class diagrams (OO)
Approach varies depending on development and deployment environments

6. Design the User Interfaces
User interface quality is critical aspect of system
Design of user interface defines how user interacts with system
GUI – windows, dialog boxes, mouse interaction
Sound, video, voice commands
To user of system, user interface is the system
User interface specialists – interface designers, usability consultants, human factors engineers

7. Design the System Interfaces
System interfaces enable systems to share and exchange information
Internal organization systems
Interfaces with systems outside organization
New system interfaces with package application that organization has purchased and installed
System interfaces can be complex
Organization needs very specialized technical skills to work on these interfaces

8. Design and Integrate the Database
System analysis data model used to create physical database model
Collection of traditional computer files, relational databases, and/or object-oriented databases
Technical requirements, such as response times, determine database performance needs
Design work might involve
Performance tuning, indexing
Normalization
Integration between new and existing databases
Choosing data access strategy (e.g., static vs. dynamic embedded SQL)
Recovery from failure (RAID, mirroring, etc.)

9. Design and Integrate the System Controls
Final design activity to ensure system has adequate safeguards (system controls) to protect organizational assets
Controls are needed for all other design activities
User interface – limit access to authorized users
System interface – protect from other systems
Application architecture – record transactions
Database – protect from software/hardware failure
Network design – protect communications

10. Deployment Environment
Deployment environment definition bridges analysis and design
Hardware
System software
Networking
Common deployment environments in which system will operate
Related design patterns and architectures for application software
Hardware / System Software decisions made in tandem, usually

11. Single-Computer and Multitier Architecture
Single-computer architecture
Mainframe-based
Limited by single machine capacity
Clustered and multi-computer architecture
Group of computers to provide processing and data storage capacity
Cluster acts as a single system
Multicomputer hardware/OS can be less similar than clustered

12. Centralized and Distributed Architecture
Distributes system across several computers and locations
Relies on communication networks for geographic connectivity
Client/server architecture dominant model for distributed computing

13. Computer Network
Set of transmission lines, specialized hardware, and communication protocols
Enables communication among different users and computer systems
Local area network (LAN) less than one kilometer long – connects computers within single building
Wide area network (WAN) over one kilometer long – implies much greater, global, distances
Router – directs information within network

14. The Internet, Intranets, and Extranets
Internet – global collection of networks that use TCP/IP networking protocols
Intranets
Private networks using same TCP/IP protocols as the Internet
Limited to internal users
Extranets
Intranets that have been extended outside the organization

15. Application Architecture
Complex hardware/networks require more complex software architectures
There are commonly used approaches (patterns) for application architecture
Client/server architecture
Three-layer client/server architecture
Web services architecture
Internet and Web-based application architecture

16. Client/Server Architecture
Client/server divides programs into two types
Server – manages information system resources or provides well-defined services for client
Client – communicates with server to request resources or services
Advantage – deployment flexibility
Location, scalability, maintainability
Disadvantage – complexity
Performance, security, and reliability

17. Three-Layer Client/Server Architecture
Layers can reside on one processor or be distributed to multiple processors
Data layer – manages access to stored data in databases
Business logic layer – implements rules and procedures of business processing
View layer – accepts user input and formats and displays processing results

18. Three-Layer Architecture

19. Service Oriented Architecture (SOA)
A service-oriented architecture is a collection of services. These services communicate with each other. The communication can involve either simple data passing or it could involve two or more services coordinating some activity. Some means of connecting services to each other is needed.
A service is a function that is well-defined, self-contained, and does not depend on the context or state of other services.

20. Service Oriented Architecture (SOA)
The following figure illustrates a basic service-oriented architecture.
Both the sender and receiver know how to communicate, but don’t care about the internal workings of each other
Services could be within a company, or you could access services from another organization – they just need to agreed on how services will communicate
Web services: SOA using internet and WWW oriented technologies.
XML
.Net
Java

21. Oracle Manufacturing System Another Company’s inventory system (SAP)
SOA - Example
Build a supply chain management system out of existing ‘components’
Oracle Manufacturing System
Another Company’s inventory system (SAP)

22. Web Services Architecture
A client/server architecture
Packages software functionality into server processes (“services”)
Makes services available to applications via Web protocols
Web services are available to internal and external applications
Developers can assemble an application using existing Web services

23. Internet and Web-Based Application Architecture
Web is complex example of client/server architecture
Can use Web protocols and browsers as application interfaces
Benefits
Accessibility
Low-cost communication
Widely implemented standards

24. Negative Aspects of Internet Application Delivery
Breaches of security
Fluctuating reliability of network throughput
Throughput can be limited
Volatile, changing standards

25. Middleware Aspect of distributed computing
Connects parts of an application and enables requests and data to pass between them
Transaction process monitors, object request brokers (ORBs), Web services directories
Designers reply on standard frameworks and protocols incorporated into middleware

26. Enterprise Application Integration (EAI)
Provides the means to share data between different applications without writing custom interfaces.
Example:
Consider a company that wants to do build an eCommerce portal.
Has a number of legacy applications (or even an ERP solution in place)
Need build the web-based eCommerce infrastructure and link with systems that do functions like process orders, manage inventory, ship products
The company decides to use a major courier service for delivery of products ordered from the web site.
The company wants an ODS for analysis of transactions taking place on the site

27. One solution – custom Interfaces
Example
eCom
Site
Order
System
Inventory
ODS
Shipping
Courier
One solution – custom Interfaces
Issues?

28. Alternative – employ EAI solution = Middleware
Example
eCom
Site
Order
System
EAI
ODS
Inventory
Shipping
Courier
Alternative – employ EAI solution = Middleware

29. Advantages of EAI Cost effectiveness Time to market Scalability
Ability to deal with complex environments

30. Summary
Systems design is process of organizing and structuring components of system to allow construction (programming) of new system
Design phase of project consists of activities that relate to design of components of new system
Application architecture, user interfaces, system interfaces, databases, network diagrams, system controls
Prototyping may be required to specify any part or all of the design

31. Summary (continued)
Inputs to design activities are diagrams built during analysis
Outputs of design are also diagrams that describe architecture of new system and detailed logic of programming components
Inputs, design activities, and outputs are different depending on whether a structured approach or an object-oriented approach is used
Architectural design adapts to development environment and decomposes design into layers