1. Lecture-5 Implementation of Information System Part - I Thepul Ginige

2. Major Topics Client/server computing Network types Groupware Training
Changeover Techniques

3. Implementation
Implementation is the process of assuring that the information system is operational
Well-trained users are involved in its operation

4. Distributed Systems Distributed systems
Use telecommunications technology and database management to interconnect people
A distributed system includes work stations that can communicate with each other and with data processors
The distributed system may have different configurations of data processors

5. Client/Server Computing
The client/server (C/S) model consists of clients requesting and the server fulfilling the request
The client is a networked computer, running a GUI interface
A file server stores programs and data
A print server receives and stores files to be printed

6. Advantages and Disadvantages of Client/Server
The advantages of a client/server system are greater computer power and greater opportunity to customize applications
The disadvantages of a client/server system are greater expense and applications must be written as two separate software components running on separate machines

7. Network Types Standard types of networks include Other types are
Wide-area network (WAN)
Local area network (LAN)
Other types are
Personal area network (PAN)
Metropolitan area network (MAN)

8. Network Configurations
There are four types of network configurations:
Hierarchical
Star
Ring
Bus

9. Hierarchical
A hierarchical network will contain several levels, with a host at the top
A host computer has many smaller computers that only communicate with the host, not with each other
The host controls all other nodes
Computers on the same level do not communicate with each other

10. Network Models Several models are available for designing a network:
A network decomposition diagram provides an overview of the system and is drawn first
A hub connectivity shows how the major hubs are connected and is drawn second
A workstation connectivity diagram shows the details of connecting the workstations

14. Groupware
Groupware is software that supports people working together in an organization
Groupware helps group members (Functions)
Schedule and attend meetings
Share data
Create and analyze documents
Unstructured communication via
Hold group conferences
Departmental-level image management
Manage and monitor workflow

15. Advantages of Distributed Systems
Advantages of distributed systems are
Data are stored where it does not affect the processing of online real-time transaction processing
Data are stored using less expensive media at local sites
Lowered equipment costs
Provide flexibility in choice of equipment manufacturer
Initially less expensive than large systems

16. Disadvantages of Distributed Systems
Disadvantages of distributed systems are
Networks must be reliable
Security may be breached
The relationships between subsystems must not be ignored

17. Training New system training must be performed Analysts must consider
Who needs to be trained
Who will train them
Objectives of training
Methods of instruction to be used
Sites
Materials

18. Sources of Training
Possible sources of training for users of information systems include
Vendors
Systems analysts
External paid trainers
In-house trainers
Other system users

19. Changeover Techniques (System changeover methods)
As technologies change, many businesses find themselves needing to change over their computer information systems.
Upgrading these systems helps them optimize their efficiency and remain competitive. Common changeover areas include security systems, database systems, accounting systems and managerial information systems.

20. Deciding which changeover technique will work best for a particular company depends on the type of changeover and degree of risk for the company. There are four popular changeover techniques.
Parallel Changeover
Direct Changeover
Phased Changeover
Pilot Changeover

21. Parallel Changeover
In a parallel changeover, the new system runs simultaneously with the old for a given period of time. Of all the techniques, this tends to be the most popular, mainly because it carries the lowest risk. If something goes wrong at any point, the entire system can be reverted back to its original state.
A primary disadvantage in running two systems at the same time is higher costs. The parallel changeover process also can be quite time-consuming.

22. Direct Changeover
Direct changeover, also referred to as immediate replacement, tends to be the least favorite of the changeover techniques.
In a direct changeover, the entire system is replaced in an instant. Basically, as soon as the new system is powered up, the old system is shut down.

23. This type of changeover carries the most risk because, if something goes wrong, reverting back to the old system usually is impossible. Using the direct changeover technique tends to work best in situations where a system failure isn't critical enough to result in a disaster for the company.

24. Phased Changeover
The phased changeover technique is considered a compromise between parallel and direct changeovers. In a phased changeover, the new system is implemented one stage at a time. As an example, consider a company working toward installing a new financial system. Implementing the new system one department at a time, the company converts accounts receivable, accounts payable, payroll, and so on.

25. Advantages to phased changeovers are their low cost and isolated errors. The main disadvantage is the process takes a long time to complete because phases need to be implemented separately.

26. Pilot Changeover
With a pilot changeover, the new system is tried out at a test site before launching it company-wide. For example, a bank may first test the system at one of its branches. This branch is referred to as the pilot, or beta, site for the program. Since parallel changeovers tend to be expensive, using the pilot changeover technique allows companies to run the new system next to their old but on a much smaller scale.

27. This makes the pilot changeover method much more cost-effective
This makes the pilot changeover method much more cost-effective. After the kinks are worked out of the system at the test site, companies usually opt to use the direct changeover technique to launch the system company-wide.