Presentation on theme: "Chapter 14 Designing Distributed and Internet Systems"— Presentation transcript:
1Chapter 14 Designing Distributed and Internet Systems Modern Systems Analysis and Design Fourth EditionChapter 14Designing Distributed and Internet Systems
2Learning ObjectivesDefine key client/server, LAN, distributed database, and middleware terms.Distinguish between file server and client/server environments.Describe alternative distributed system designs.Describe standards for Internet-based system design.Describe options for ensuring Internet design consistency.Describe site management issues.Describe issues related to managing online data.
4The Process of Designing Distributed and Internet Systems The process is similar to designing single-location systemsMore opportunity for failure due to number of componentsMain issues involve ensuring reliability, availability, survivability, performance
5Deliverables and Outcome A document that consolidates system design information:Description of each siteDescription of data usage for each siteDescription of business process for each siteContrasts of alternative IS architectures for site, data and processing needs of each site
6Designing Systems for Local Area Networks (LAN) LAN: the cabling, hardware, and software used to connect workstations, computers, and file servers located in a confined geographical areaMain LAN configuration optionsFile Server architectureClient/Server architecture
7File Server Architectures A device that manages file operations and is shared by each client PC attached to a LANDBMS use in a file server:One copy of the DBMS is on the file server and concurrently running copies are on client PCs.All data manipulation is performed on the client PC.
9Limitations of File Servers Excessive data movementEntire data tables must be transferred instead of individual recordsNeed for powerful client workstationsEach client workstation must devote memory to a full DBMSDecentralized data controlComplicates record concurrency control, recovery, and security
10Client/Server Architectures Application processing is divided between client and server.Client manages the user interface.Database server is responsible for data storage and query processing.
11Client: front-end software provides user interface and data manipulation functions Database engine: back-end DBMS software runs on the server to provide database processing and shared access for clients
12Application Program Interface (API) Software building blocks that ensure standardization of modules for data exchange between clients and serversCommon API interface can be used for communication between client and any kind of DBMS (DB2, SQL Server, MySQL, Oracle)
13Client/Server Advantages and Cautions Leverages benefits of microcomputer technologyProcessing performed close to data sourceImproves response timeReduces network trafficFacilitates use of GUIsEncourages acceptance of open systemsCautionsDifficult migration from file server to client/serverCompatibility issuesLimited system design and performance monitoring tools
15Advanced Forms of Client/Server Architecture Three-tiered client/serverThree logical and distinct applicationsData managementPresentationAnalysisMiddlewareCombination of hardware, software, and communication technologies that bring together three distinct applications into one environmentApplication ServerServer where data analysis functions are performed
16Advantages of Three-tiered Architectures Applications can be partitioned in a way that best fits the organizational computing need.Easier customization: application code resides on application server, so change done only in one place.Easier maintenance: data analysis is separate from user interface, so changing one can be done independently of the other.
17Approaches to Designing Client/Server Architectures Distributed PresentationRemote PresentationRemote Data ManagementDistributed FunctionDistributed DatabaseDistributed Processing
18Distributed Presentation Freshen up delivery of existing server-based applications, typically running on legacy mainframe computers, to distributed clients using screen scrapper technology
19Remote PresentationAll data presentation functions are on the client, providing greater flexibility of presentation than the distributed presentation option.
20Remote Data Management All software except data management is on client, this is closest to the traditional client/server mode.
21Distributed FunctionAnalysis functions are split between client and server, with all presentation on client and all data management on server. Requires coordination between analysis function on client and server, making it difficult to develop and maintain.
22Distributed DatabaseClient has all functionality, except that data storage and management is shared between client and server. A distributed database is unstable, and it is very difficult to ensure compatibility and communication between client and server.
23Distributed Processing Combines distributed function and distributed database, maximizing flexibility of analysis and data management
24Designing Internet Systems Most new system development focuses on Internet-base applications (for internal processing, business-to-business, and business-to-consumer)Main design issues:StandardsSeparating content from displayFuture evolutionSite consistencySite managementOnline data management
25Standards for Internet Design Internet design is simpler than client/server due to proliferation of standardsTypes of Standards:Domain naming (BIND): a method for translating domain names into Internet Protocol (IP) addressesHypertext Transfer Protocol (HTTP): a communication protocol for exchanging information on the InternetHypertext Markup Language (HTML): the standard language for representing content on the Web via command tags
26Separating Content from Display HTML has limitations due to format orientation of tagseXtensible Markup Language (XML) has been developed to separate content from displayXML: an Internet authoring language that allows designers to create customized tags that represent data transmitted between applications
27Future Evolution Move from desktop PCs to thin clients Most processing and data storage occurs on the serverUse of wireless mobile devicesWireless Access Protocol (WAP): a wireless version of HTTPWireless Markup Language (WML): a wireless version of HTML
28Site ConsistencyProfessionalism requires a consistent look-and-feel across all pages of a Web siteAids to consistency:Cascading Style SheetsA set of style rules that tells a Web browser how to present a documentExtensible Style Language (XSL)Specification for separating style from content when generating HTML documents
30Site Management Issues Customer Loyalty and TrustworthinessConveyed byDesign qualityUp-front disclosureComprehensive, correct and current contentConnected to the rest of the WebData securityPersonalizationCustomization
32Online Data Management Context developmentMethod of understanding how a system fits within the existing business activities and dataIntegration depthMeasurement of how far a system penetrates into the existing technology infrastructureOrganizational breadthMeasurement that tracks the core business functions affected by a system
34Online Transaction Processing (OLTP) Refers to immediate automated responses to the requests of usersDesigned to handle multiple concurrent transactionsPlays a large role in electronic commerce applications
35Online Analytical Processing (OLAP) Refers to graphical software tools that provide complex analysis of data stored in a database.OLAP server is the chief componentGood for time series and trend analysisEnables user to “drill-down” into the data
36Merging Transaction and Analytical Processing Requires combining operational and informational components
37Data Warehousing Collection of data for decision support Key features Subject-oriented: organized around key subjectsIntegrated: data are collected from many operational systems and made to conform to standardsTime-variant: data contains a time dimensionNonvolatile: data cannot be updated by users
38Steps in Building and Using a Data Warehouse Extract data from various source system files and databasesTransform, integrate, and load the dataData warehouse is a read-only environmentUsers access via query languages and analytical tools
39Data Warehouse Architectures Two-levelData warehouse and decision support environmentThree-levelOperational systemsEnterprise data warehouseCentralized, integrated data warehouseControl point and single source of all data made available to end usersData martsA data warehouse that is limited in scope based upon aggregation and selection
42Summary In this chapter you learned how to: Define key client/server, LAN, distributed database, and middleware terms.Distinguish between file server and client/server environments.Describe alternative distributed system designs.Describe standards for Internet-based system design.Describe options for ensuring Internet design consistency.Describe site management issues.Describe issues related to managing online data.