Chapter 9 Designing Systems for Diverse Environments

SAD/CHAPTER 92 Learning Objectives To gain an appreciation of the diversity of design and development environments faced by the modern analyst To understand the advantages and disadvantages of centralized versus distributed data systems To learn the differences between the file server and the client – server approaches to networking

SAD/CHAPTER 93 Learning Objectives To explore the common network topologies and understand their relative advantages and disadvantages To gain an appreciation for development issues within ERP, collaborative, intranet, and data warehousing environments

SAD/CHAPTER 94 Application Development Environment Central computing environment Single processor Clustered approach Distributed computing environment LAN/WAN Internet/WWW

SAD/CHAPTER 95 Figure 9-1. Typical Clustered Central Computing System

SAD/CHAPTER 96 The Distributed IS Some subsystems … Need to interact with other subsystems Need to share files with other subsystems Require little interaction with other subsystems

SAD/CHAPTER 97 Figure 9-2. Typical Distributed Computer System

SAD/CHAPTER 98 The Distributed IS Reliability A particular piece of data is available at a given time regardless of the location of the user Survivability System ’ s ability to continue to provide service to its users despite the failure of one or more nodes

SAD/CHAPTER 99 The Drive to Distribute The cost of PCs is dropping rapidly. The interface and computing power of such devices is increasing. Increased communications bandwidth and inexpensive storage costs The demand for locally specific applications is rising. The Internet and the WWW provide a natural connectivity vehicle to access data and applications from around the globe.

SAD/CHAPTER 910 Table 9-1. Comparative Pros and Cons of Distributed Computing

SAD/CHAPTER 911 Types of Distribution Distributed System Distributed Applications Distributed Data Hardware Architecture File Server Client Server

SAD/CHAPTER 912 Distributed Applications Allowing geographically dispersed end users to access and use a variety of software applications Applications can be stored in a single location and accessed by any processor connected to the system A single application can be replicated to multiple locations throughout the network

SAD/CHAPTER 913 Distributed Data Data can be either replicated across multiple sites for ease of access or Partitioned such that a portion of the data resides in several locations throughout the network

SAD/CHAPTER 914 File Server versus Client Server Approach File Server Manages the various file operations associated with the system and can be thought of as an additional hard dive for each workstation Client Server Processing load for an application is divided between the workstation and the server

SAD/CHAPTER 915 Figure 9-3. Typical LAN/WAN Connectivity

SAD/CHAPTER 916 Figure 9-4. Comparison of File Server and Client/Server Approach

SAD/CHAPTER 917 Connectivity Diagram Location Connectivity Diagram (LCD) Depicts the shape of a network in terms of the location of the various components on the network

SAD/CHAPTER 918 Table 9-2. Symbology for Location Connectivity Diagrams

SAD/CHAPTER 919 Figure 9-5. Example of a Location Connectivity Diagram

SAD/CHAPTER 920 Connection Topologies Bus Topology Ethernet Ring Topology Token Ring Star Topology

SAD/CHAPTER 921 Figure 9-6. Typical Bus Network Topology

SAD/CHAPTER 922 Figure 9-7. Typical Token-Ring Network Topology

SAD/CHAPTER 923 Figure 9-8. Typical Star Network Topology

SAD/CHAPTER 924 Table 9-3. Comparative Advantages and Disadvantages of Common Network Topologies

SAD/CHAPTER 925 Managing Distributed Data Data Replication Create a copy of each of the databases contained in the system at each workstation Provide users with high reliability of access to the data Storage requirements are significantly increased

SAD/CHAPTER 926 Managing Distributed Data Data Partitioning Partition the data using some logical approach such that the contention for data across workstations is minimized Location transparency Horizontal partitioning Vertical partitioning

SAD/CHAPTER 927 Figure 9-9. Lotus Notes Database Replication Control Screen

SAD/CHAPTER 928 Table 9-4. Comparative Advantages and Disadvantages of Data Distribution Methods

SAD/CHAPTER 929 Design for Distributed Systems Distributed systems characteristics A large number of interconnected machines Open (heterogeneous) hardware and software systems Complete autonomy over hardware and software resources Dynamic system configuration and integration Time-sensitivity of the expected solution

SAD/CHAPTER 930 Table 9-5. Traditional Design Assumptions versus Distributed Design Assumptions

SAD/CHAPTER 931 Design for Distributed Systems Challenges Separation Diversity Federalism Concurrency

SAD/CHAPTER 932 Design for Collaboration The system should support individual works as well as collaboration. The system must afford mutual intelligibility. The system must support simultaneous access. Collaborative wearable computers

SAD/CHAPTER 933 Figure Screenshot of Collaborative Work Environment

SAD/CHAPTER 934 Figure Examples of Currently Available Wearable Computing Devices

SAD/CHAPTER 935 Designing for Enterprise Resource Planning ERP Features ERP systems are installed on a typical DBMS Require initial setup according to the organization ’ s process ERP system includes reporting tools for main and ad hoc reporting

SAD/CHAPTER 936 Figure Comparison of Typical Organization IS with ERP Approach

SAD/CHAPTER 937 ERP Implementation Comprehensive Implementation Focus on business improvement rather than on technical improvement Compact Implementation Focus on making the technical migration to the ERP

SAD/CHAPTER 938 Designing for Intranets Focus on tasks rather than documents for simple data capture Aim to integrate those tasks into distinct processes Encourage collaboration by creating shared and familiar spaces

SAD/CHAPTER 939 Intranet Design Myths Intranets are cheap Build it and they will come Intranets are for really big organizations Intranets requires an Internet connection and are not secure Intranet are low maintenance applications Intranets are an IS thing

SAD/CHAPTER 940 Designing for the Data Warehouse Assumptions DW is physically separated from all other operational systems DW holds aggregated data and transactional data for management separate from those used for on-line transaction processing

SAD/CHAPTER 941 Table 9-6. Operational Data Store and Data Warehouse Characteristics

SAD/CHAPTER 942 Figure Components of the Data Warehouse Architecture

SAD/CHAPTER 943 Data Warehouse Topology Virtual or point-to-point Central Distributed

SAD/CHAPTER 944 DW Implementation Seven Deadly Sins If you build it, they will come Omission of an architectural framework Underestimating the importance of documenting assumption Failure to use the right tool for the job

SAD/CHAPTER 945 DW Implementation Seven Deadly Sins (continued) Life cycle abuse Ignorance concerning the resolution of data conflicts Failure to learn from mistakes - End -

SAD/CHAPTER 946 Chapter Summary This chapter established the range of diverse environments you can expect to encounter during your career. Despite the diversity of the environments, the basic tenets and foundations of good system design and development still prevail.

Chapter 9 End of Chapter