Business data communications 5e by stallings chapter 03

Chapter 3 : Distributed Data Processing Business Data Communications, 5e... Centralized Data Processing• Centralized computers, processing, data, control, support • What are the advantag

Chapter 3 : Distributed Data Processing

Business Data Communications, 5e

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

• What are the disadvantages???

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 in control of corporate information resources

• Suboptimal procurement

• Duplication of effort

Client/Server Architecture

• Combines advantages of distributed and centralized computing

• Cost-effective, achieves economies of scale

• Flexible, scalable approach

• Uses Internet-based standards & TCP/IP

• Content is accessible only to internal users

• A specialized form of client/server architecture

• Can be managed (unlike Internet)

• Similar to intranet, but provides access to controlled number of outside users

– Vendors/suppliers

– Customers

Distributed applications

• Vertical partitioning

– One application dispersed among systems – Example: Retail chain POS, inventory,

analysis

• Horizontal partitioning

– Different applications on different systems – One application replicated on systems

– Example: Office automation

Other forms of DDP

• Distributed devices

– Example: ATM machines

• Network management

– Centralized systems provide management and control of distributed nodes

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