1. The Design of System Architecture

2. System Architecture
System architecture translates the logical design of an information system onto a physical structure includes hardware, software, network support, processing methods, and security.

4. 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

5. 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

6. Single-, Clustered, and Multicomputer Architectures

7. 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

8. 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

9. Client/Server Computing
Information processing is distributed among several workstations and servers on a network, with each function being assigned to the environment that is best suited to perform it. The client initiates the requests and the server responds.
Consolidate the virtues of traditional time-shared mainframe and mini-computer paradigms with the advantages of personal computers, workstations, and local area networks

10. Components of Client/Server Computing
Three interrelated components Client - the front-end Server - the back-end Network - the middle ware
Many to many relationship between clients and servers.

11. 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

14. Interaction Among Multiple Clients and a Single Server

15. Client/Server Architectural Process
Decompose application into client and server programs, modules, or objects
Identify resources or services that can be centrally managed by independent software units
Determine which clients and servers will execute on which computer systems
Describe communication protocols and networks that connect clients and servers

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

17. Three-Layer Architecture

22. Client/Server Tiers and Middleware
Two-tier design: client - server
Three-tier design:
client – application server – data server
Middleware
Special utility software that enables the tiers to communicate and pass data back and forth.
A transparent interface that enables system designers to integrate dissimilar software and hardware.

24. Three-tier Client/Server System
Figure 1. Three-tiered client/server architecture
Three-tier Client/Server System

25. Client/Server Advantages
Provide scalability, portability, and interoperability through standard-based openness
Respond to the organization’s need for easy information access, flexibility, smooth administration, reliability, security and proficient application development
Mix, match, and combine diverse data elements located in different, often incompatible systems

26. Client/Server Disadvantages
Acceleration of complexity
High hidden costs Technical support cost End-user operations cost Administration cost

27. 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

28. Web Services Architecture
WSDL: Web Service Description Language
UDDI: Universal Description, Discovery and Integration
SOAP: 'Simple Object Access Protocol
XML: Extensible Markup Language

29. 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

31. Multi-tiered Web Service System

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

33. The Design of Communication Networks

34. Networks
Network - A set of interconnected devices that share a directory and can thus access each other
The directory provides an address for each component of the network
If the device is not included in the directory, it is not part of the network

35. Components of a Network
Terminals and workstations
Transmission links
Transmission methods
Nodes and switches
Network architecture and standards

37. The layered protocol system concept
receive a
letter
send a
letter
Application
Application
logical
link
mail
sorting
mail
sorting
Network
Network
mail
unpacking
and checking
mail
packaging
Data link
Data link
physical
link
Physical
Physical
transportation

38. Layered Architecture
Clear division of functionality gives modular approach to development and ease of standardization.
Application independence - software assumes that services are available - no need to know about implementation details.
Facilitates maintenance - can replace/omit or nominally implement a layer

39. Classification of Networks
By technology used: cable, wireless, …
By topology: ring, bus, star
By geographic scope: LAN, WAN, MAN
By type of ownership: Public, Private, VPN

40. 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

41. A Possible Network Configuration for RMO

43. McMaster Campus Networks

44. 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

45. Identify the business criteria for the telecommunications platform
Translate business to technology along three dimensions of business functionality
Reach: the locations/people/organizations to which we must link
Range: the variety of information and transactions we must be able to share
Responsiveness: the level of service we guarantees, in terms of speed, reliability, and security

47. Reach Levels of Reach Connection is not communication
Within a single location
Across a firm’s domestic locations
Across international locations
To customers and supplies with the same technology base as the firm’s
To all customers and suppliers
To anyone, anywhere
Connection is not communication

48. Range
Range involves the information and transactions that must be shared across business functions and processes
Levels of Range
Simple messages
Access to separate data stores
Independent transactions
Cooperative transactions
Object-oriented thinking

49. Responsiveness
Refers to the level of service we must guarantee, in terms of speed, reliability, and security
Levels of responsiveness
Non-immediate response - need not be on-line
Immediate response - on-line during office hours - airline
On-demand service - 24 hours a day - police
Perfect service - always work with high security - defense

50. 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

51. Network Diagram for RMO Customer Support System