SYSTEM DESIGN

In the design phase of the SDLC, the project team must figure out how the new system will fulfill the requirements specified in the System Requirements Report. The project team should identify several potential hardware and software solutions by brainstorming and researching case studies at Web sites and in computer magazines. When evaluating hardware solutions for a new information system, the project team considers the overall architecture of the information system based on level of automation, processing methodology, and network technology. Some information systems provide a higher level of automation than others. For instance, a point-of-sale system with a low level of automation might require the checkout clerk to enter credit card numbers from a keypad. At a higher level of automation, a magnetic strip reader automates the process of entering a credit card number. A further level of automation is achieved by using a pressure-sensitive digitizing pad and stylus to collect customer signatures.

An information system can be designed for centralized and distributed processing. Distributed processing in a client/server or peer-to-peer environment is very popular because it provides high levels of processing power at a low cost. Virtually every information system requires a network, so the project team must examine network alternatives, such as LANs, extranets, intranets, and the Internet. Many information systems require a complex mixture of networks, such as a LAN in each branch office connected to a company intranet, with customers accessing selected data using the Internet.

The project team might consider software alternatives, such as whether to construct the system “from scratch” in a programming language or select a turnkey system. An information system “from scratch” is usually costly, but offers the most flexibility for meeting the system requirements. An application development tool is essentially a type of software construction kit containing building blocks that can be assembled into a software product. It includes expert system shells and database management systems.

Commercial software for an information system is usually a series of preprogrammed software modules. It eliminates much of the design work required with programming languages or application development tools. It is available for standard business functions and market businesses and organizations. Although most commercial software has some customization options, in many cases, it cannot be modified to exactly meet every system requirement.

A turnkey system consists of hardware and commercial software designed to offer a complete information system solution. Like commercial software, a turnkey system must be extensively evaluated to determine whether it can satisfy system requirements.

To determine the best solution, the project team devises a list of criteria for comparing each potential solution. It isn’t complicated if the project team uses a decision support worksheet. After the project team selects a solution, the next task is to select the hardware and software. Sometimes the team knows exactly what brand, model, or version of hardware and software are required. At other times, the team has a general understanding, but needs vendor help selecting specific products. RFPs and RFQs help the team collect information for these important decisions. Technical criteria for hardware might include processing speed, reliability, upgradability, maintenance costs, and warranty. Technical criteria for software might include reliability, compatibility, and the availability of patches to fix program errors.

Next step depends on the type of solution selected. If a turnkey solution is selected, the next step might be to get approval to move into the implementation phase of the SDLC. In contrast, if the project team selected a solution that requires custom programming, the team’s systems analysts will create a set of application specifications. Many project failures are often referred to as feature creep. Proposed changes should be managed within a formal process that includes written change requests.

Comprehension check. Choose the ending for each sentence from the two versions given.

1. Distributed processing in a client\server or peer-to-peer environment

a) is very popular because it provides high levels of processing power at a low price.

b) is very popular because it provides the highest levels of processing power at a high price.

2. A series of programmed software modules

a) eliminates much of the design work required with programming languages or application development tools.

b) requires much of the design work with programming languages or application development tools.

3. An application development tool is

a) essentially a type of software construction kit containing building blocks that can be assembled into a software product.

b) a software kit that can’t be assembled into a software product.

4. RFPs and RFQs help the team

a) collect information for the important decisions.

b) determine information for the important decisions.

5. Technical criteria for hardware might include

a) processing speed, reliability, upgradability, maintenance cost, and warranty.

b) reliability, compatibility, and the availability of patches to fix program errors.

6. Many project failures are often referred to as features creep

a) because of changes in needs.

b) because old features tend to creep into the development process.

Vocabulary practice

1. Which word does not belong to the group?

a) research, require, study, examine;

b) collect, gather, determine, take;

c) reliability, compatibility, digitizing, availability;

d) creep ,steal, get into, include;

e) card, set, kit, collection;

f) sheave, block, database, pulley.

Date: 2015-01-12; view: 1183