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

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

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

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

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

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

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)

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

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

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

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 e-mail Hold group conferences Departmental-level image management Manage and monitor workflow

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

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

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

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

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.

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

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.

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.

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.

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.

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.

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.

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.