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The Design of System Architecture

The Design of System Architecture. 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. Deployment Environment.

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The Design of System Architecture

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  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.

  3. 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

  4. 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

  5. Single-, Clustered, and Multicomputer Architectures

  6. 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

  7. 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

  8. 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

  9. Components of Client/Server Computing • Three interrelated componentsClient - the front-endServer - the back-endNetwork - the middle ware • Many to many relationship between clients and servers.

  10. 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

  11. Interaction Among Multiple Clients and a Single Server

  12. 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

  13. 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

  14. Three-Layer Architecture

  15. 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.

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

  17. 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

  18. Client/Server Disadvantages • Acceleration of complexity • High hidden costsTechnical support costEnd-user operations costAdministration cost

  19. 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

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

  21. 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

  22. Multi-tiered Web Service System

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

  24. The Design of Communication Networks

  25. 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

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

  27. 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

  28. 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

  29. 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

  30. 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

  31. A Possible Network Configuration for RMO

  32. McMaster Campus Networks

  33. 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

  34. 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

  35. Reach • Levels of Reach • 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

  36. 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

  37. 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

  38. 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

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