Systems Analysis I System Implementation

1. Systems Analysis ISystem Implementation ISYS 200 Glenn Booker Week #9

2. System Implementation • Now we get to actual creation of the system we’ve designed • Notice the text covers this fairly quickly, since many other courses are needed to cover the skills and concepts needed for implementation • Key aspects of implementation include how the information is distributed, providing user training, and choosing a good conversion strategy Week #9

3. Implementing Distributed Systems • Variations of client/server (C/S) networks have been widespread since the 1980’s, and continue to evolve • In basic form, C/S refers to some system processing being done by a PC-based client application, while other parts are done on the server • Now we tend to have many types of specialized servers instead of just one Week #9

4. Implementing Distributed Systems • Servers can include many varieties • File servers, to hold shared files • Print servers, to manage print jobs • Database servers, to run a shared database system • Now we might add web servers to control access to our system, and various kinds of application servers Week #9

5. Types of Networks • The basic types of networks include • LAN – Local Area Network, a typical home or office-sized network • WAN – Wide Area Network, a corporate network which spans continents • WLAN – Wireless LAN, a LAN which uses wireless (Wi-Fi) connections Week #9

6. Network Connections • Common network connections include • Ethernet cable, an 8-wire cable (RJ-45 plugs) similar to 4-wire phone lines (RJ-11) • Fiber optic cable, for Gigabit and faster networks • “Thick” and “thin” Ethernet cables are pretty obsolete Week #9

7. Organizing Networks • There are four major topologies (structures) for a physical computer network • Bus • Ring • Star • Hierarchical • They may be combined in some cases, such as a hierarchical top level structure, and stars used locally Week #9

8. Network Topology - Bus • A key function to achieve connectivity among computers is definition of the network topology • The “bus” is the simplest topology - it connects computers along a single line • A peer-to-peer (server-less) network uses the bus topology, with AppleTalk or Ethernet Week #9

9. Ring Topology • The ring topology connects computers in a loop, and passes packets of data from one computer to the next • IBM’s Token Ring is the most famous example • Bad if a computer falls off the network – hard to tell who “dropped” the packet Week #9

10. Star Network • Many clients may be connected to each server across a star network • The middle of each star is a server • Servers are connected to each other • Very common – think of using a server for each department, and be able to control which departments can see each other Week #9

11. Hierarchical Network • This is a set of nested star networks, looks kind of like an organization chart • Generally the servers get smaller the further down the hierarchy • Sometimes used in very large corporations, where the biggest servers store company-wide or division-wide data Week #9

12. Network Modeling • A network for a system or an organization is developed to meet a need-to-know basis • Ensure people who need to see data can get to it • And those who don’t need to, can’t • Networks are generally broken into portions or segments which correspond to organizational units • One segment is the Accounting dept., another is the Human Resources dept., and so on Week #9

13. Network Modeling • Segments of the network are separated from each other by network hardware • Routers, switches, hubs, bridges, and other toys are the hardware involved* • The type of hardware is chosen based on • The protocols involved • The distances between segments • The amount of logic or processing needed for isolation * Cisco has some nice tutorials to help explain the hardware in more detail Week #9

14. Network Modeling • Based on the type of network topology chosen, a network decomposition diagram(p. 628) can be developed to show the parts of a network, and who they can talk to easily • Different symbols can be used to show hubs at the center of each segment, key types of users, groups of related workstations, and external networks Week #9

15. Network Modeling • In contrast, a hub connectivity diagram shows the hubs of your network, and how far they are from each other • A more detailed version is the workstation connectivity diagram, which examines one segment (hub) and looks at the distances involved in its connections Week #9

16. Distribution • Since computers were invented, the amount of distribution of data and processing functions has tended to go up without end • The ultimate incarnation is web-based computing, where both data storage and processing are distributed across possibly hundreds of computers • While this allows more flexibility and often better use of resources, it adds reliability and security issues Week #9

17. Training Users • As a system is being implemented, several key aspects of training need to be managed • While end user training is often considered, there may be other kinds of training needed • Training for other user roles, including managers • Training for support staff of the operational system (help desk, and system maintainers) • Training for those who will train users (train-the-trainer), if there are many end users Week #9

18. Training Users • Training may also be needed on commercial components of the system, so vendors may need to provide training on how their OS or bridge works • Training may be conducted by systems analysts, consultant trainers, or training staff within your organization Week #9

19. Conducting Training • Training needs to be planned carefully • Need to determine its objectives and methods • Need to determine where to conduct training • Need to develop training materials, and keep them consistent with the actual system • User training needs to be done before the system is implemented, but not so long that they forget what they learned! Week #9

20. System Conversion Strategies • To implement a new information system, you are presumably replacing whatever existing system (if any) and processes (whether manual and/or automated) that are currently performing the system’s functions • Need to choose a conversion strategy • How to convert from doing things the old way to using the new system Week #9

21. System Conversion Strategies • There are about five types of conversion strategies to choose from (p. 636) • Direct changeover means the old system is used until a stated date and time, after that, the new system is used • Parallel conversion means that the old and new systems are used together for some period of time, until you’re okay to shut off the old system Week #9

22. System Conversion Strategies • Gradual conversion tries to slowly phase in the percent of transactions handled by the new system, until it does everything • Modular prototype conversion means that the new system is developed in chunks of functionality; when a set of functions are ready to be released, it becomes operational and that part of the old system is shut down • The distributed conversion strategy works geographically – convert sites one group at a time until they are all done Week #9

23. Security Concerns • Both traditional and web-based systems have security and privacy issues • Security concerns can be divided into physical, logical, and behavioral • Physical security is making sure the computer facilities aren’t broken into, the computers don’t get stolen, backup tapes don’t grow legs, etc. Week #9

24. Security Concerns • Logical security is within the system software • To ensure that users are validated, • Passwords expire and don’t get reused, • Passwords are sufficiently complex • User access to system functions really is controlled by their security profiles • Firewalls on public Internet access points also fit into this category Week #9

25. Security Concerns • Behavioral security is avoiding compromise of your system from inside – by its users • Screening potential employees • Making security policies clear • Monitor behavior which may compromise the system • Limit number of incorrect sign-on attempts • Monitor your own software activity and look for suspicious activities • Control distribution and/or encrypt system outputs • Shred discarded system outputs Week #9

26. Internet Security • Basic aspects of Internet security include • Use and maintain virus protection software • Filter email from spam • Restrict Internet access by employees • Monitor network connections to the public • Encrypt anything passing through the Internet • The Rainbow Series of reports by the NIST is a widely used set of computer security standards Week #9

27. Privacy Concerns • Privacy has become a key public issue • Establish clear privacy policies, and follow them • Only get required information • Make personal information optional, if you must ask for it • Use anonymous sources about clients where possible • Be ethical Week #9

28. System Evaluation • Once the new system is fully operational, it is important to evaluate its success • Go back to the system objectives developed from the problems and opportunities analysis • Measure the quantities described in the objectives • Customer satisfaction, system throughput, number of transactions, number of bad transactions, … • Compare the measurements to the predicted values, and analyze differences between them Week #9