Business data communications 4e chapter 3

Chapter : Distributed Data Processing Business Data Communications, 4e Centralized Data Processing ✘ Centralized computers, processing, data, control, support ✘ What are the advantages? ✘ Economies of scale (equipment and personnel) ✘ Lack of duplication ✘ Ease in enforcing standards, security Distributed Data Processing ✘ Computers are dispersed throughout organization ✘ Allows greater flexibility in meeting individual needs ✘ More redundancy ✘ More autonomy Why is DDP Increasing? ✘ Dramatically reduced workstation costs ✘ Improved user interfaces and desktop power ✘ Ability to share data across multiple servers DDP Pros & Cons ✘ There are no “one-size-fits-all” solutions ✘ Key issues ✘ How does it affect end-users? ✘ How does it affect management? ✘ How does it affect productivity? ✘ How does it affect bottom-line? Benefits of DDP ✘ Responsiveness ✘ Availability ✘ Correspondence to Org Patterns ✘ Resource Sharing ✘ Incremental Growth ✘ Increased User Involvement & Control ✘ End-user Productivity ✘ Distance & location independence ✘ Privacy and security ✘ Vendor independence ✘ Flexibility Drawbacks of DDP ✘ More difficulty test & failure diagnosis ✘ More components and dependence on communication means more points of failure ✘ Incompatibility of components ✘ Incompatibility of data ✘ More complex management & control ✘ Difficulty controlling information resources ✘ Suboptimal procurement ✘ Duplication of effort Reasons for DDP ✘ Need for new applications ✘ On large centralized systems, development can take years ✘ On small distributed systems, development can be component-based and very fast ✘ Need for short response time ✘ Centralized systems result in contention among users and processes ✘ Distributed systems provide dedicated resources The DP “Pendulum” ✘ Centralized systems (mainframes, etc) ✘ Distributed systems (PCs) ✘ Networked systems ✘ Client-Server computing Client/Server Architecture ✘ Combines advantages of distributed and centralized computing ✘ Cost-effective, achieves economies of scale ✘ Flexible, scalable approach Intranets ✘ Uses Internet-based standards & TCP/IP ✘ Content is accessible only to internal users ✘ A specialized form of client/server architecture Extranets ✘ Similar to intranet, but provides access to controlled number of outside users ✘ Vendors/suppliers ✘ Customers Distributed applications ✘ Horizontal partitioning ✘ Different applications on different systems ✘ One application replicated on systems ✘ Example: Office automation ✘ Vertical partitioning ✘ One application dispersed among systems ✘ Example: Retail chain POS, inventory, analysis Distributed data ✘ Centralized database ✘ Pro: No duplication of data ✘ Con: Contention for access ✘ Replicated database ✘ Pro: No contention ✘ Con: High storage and data reorg/update costs ✘ Partitioned database ✘ Pro: No duplication, limited contention ✘ Con: Ad hoc reports more difficult to assemble Networking Implications ✘ Connectivity requirements ✘ What links between components are necessary? ✘ Availability requirements ✘ Percentage of time application or data is available to users ✘ Performance requirements ✘ Response time requirements ... analysis Distributed data ✘ Centralized database ✘ Pro: No duplication of data ✘ Con: Contention for access ✘ Replicated database ✘ Pro: No contention ✘ Con: High storage and data reorg/update costs...Centralized Data Processing ✘ Centralized computers, processing, data, control, support ✘ What are the advantages? ✘ Economies of scale... Dramatically reduced workstation costs ✘ Improved user interfaces and desktop power ✘ Ability to share data across multiple servers DDP Pros & Cons ✘ There are no “one-size-fits-all” solutions ✘ Key