Systems Development Tools and Techniques

Systems Development Tools and Techniques

In addition to understanding business operations, systems analyst must know how to use a variety of techniques, such as modeling, prototyping, and computer-aides systems engineering tools to plan in a team environment, where input from users, managers, and IT staff contributes to the system design.

MODELING

Modeling produces a graphical representation of a concept or process that systems developers can analyze, test, and modify. A system analyst can describe and simplify an information system by using a set of business, data, object, network, and process models.

A business model, or requirements model, describes the information that a system must provide.  A data model describes data structure and design. An object model describes objects, which combine data and processes. A network model describes the design and protocols of telecommunications links. A process model describes the logic that programmers use to write code modules. Although the models might appear to overlap, they actually work together to describe the same environment from different points of view.

PROTOTYPING

Prototyping tests system concepts and provides an opportunity to examine input, output, and user interfaces before final decisions are made. A prototype is an early working version of an information system. Just as an aircraft manufacturer test a new design in a wind tunnel, systems analysts construct and study information systems prototypes. A prototype can serve as an initial model that is used as benchmark to evaluate the finished system, or the prototype itself can develop into the final version of the system. Either way, prototyping speeds up the development process significantly.

A possible disadvantage of prototyping is that important decisions might be made too early, before business or IT issues are understood thoroughly. A prototype based on careful fact finding and modeling techniques, however can be an extremely valuable tool.

COMPUTER-AIDED SYSTEM ENGINEERING (CASE) TOOLS

 Computer-aided systems engineering (CASE), also called computer-aided software engineering, is a technique that uses powerful software, called CASE Tools, to help system s analyst’s develop and maintain information systems. CASE tools provide an over all framework for systems development and support a wide variety of design methodologies, including structured analysis and object-oriented analysis.

Because CASE tools make it easier to build an information system, they boost it productivity and improved the quality of the finished product.

In addition to traditional CASE tools system developers often use project management tools, such as Microsoft Project, and special –purpose charting tools, such as Microsoft Visio, which is shown in figure 1-23. a system analyst’s can use Visio to create many different types of diagrams, including block diagrams. Building plans, forms and charts, maps, network diagrams, and organization charts, Visio is described in more detail in Part 2 of  the Systems Analyst’s Toolkit.

SYSTEMS DEVELOPMENT METHODS

There are various methods for developing computer-based information systems. Structured analysis is the most popular method, but a newer strategy called object-oriented analysis and design also is used widely. Each method offers many variations. Some organizations develop their own approaches or adopt methods offered by software suppliers, CASE tool vendors, or consultants. Most IT experts agree that no single, best system development strategy exists. Instead, a systems analyst should understand the alternative methodologies and their strengths and weaknesses.

STRUCTURED ANALYSIS

Structured analysis is a traditional systems development technique that is time-tested and easy to understand. Structured analysis uses a series of phases, called the systems development cycle (SDLC), to plan, analyze, design, implement and support an information system. Although structured analysis evolved when most systems were based on mainframe processing, it remains a dominant systems development method.

Structured analysis uses a set of processes models to describe a system graphically. Because it focuses on processes that transform data in useful information, structured analysis is called a process-centered technique. In addition to modeling the processes structured analysis includes data organization and structure, relational database design and user interfaces issue.

Process modeling identifies the data flowing into a process, the business rules that transform the data, and the resulting output data flow.

OBJECT –ORIENTED ANALYSIS

Where as structured analysis treats processes and data as separate components, object-oriented analysis (O-O) components data and the process that act on the data into things called objects. System’s analyst use O-O to model real-world business process and operation. The result is a set of software objects that represent actual people, things, transaction, and events. Using an O-O programming language, a programmer then writes the code that creates the objects.

An object is a member of a class, which is a collection of similar objects. Objects possess characteristic called properties, which the objects inherits from its class or possess on its own.

JOINT APPLICATION DEVELOPMENT AND RAPID APPLICATION DEVELOPMENT

In the past, IT departments sometimes developed systems without sufficient input from users. Not surprisingly, users often were unhappy with the finished product. Over time, many companies discovered that systems development teams  composed of IT staff, users, and managers could complete their work more rapidly an produce better results. Two methodologies became popular: joint application development (JAD) and rapid application development (RAD). Both JAD and RAD use teams composed of users, managers, and IT staff. The difference is that JAD focuses on team-based fact-finding, which is only one phase of the development process, while RAD is more like a compressed version of the entire process. JAD and RAD are described in more detail in Chapter 3.

OTHER DEVELOPMENT STRATEGIES

In addition to structured analysis and O-O methodologies, you might encounter systems development techniques. For example Microsoft Offers an approach called Microsoft Solution Framework (MSF), which document the experience of its own IT teams.

Using an MSF, systems analysts design a series of models, including a risk management model; a team model, and a process model, among others. Each model has a specific purpose and output that contributes to the overall design of the system. Although the Microsoft processes differ from the SDLC phase-oriented approach, MSF developers perform the same kind of planning, ask the same kinds of fact-finding questions, deal with the same kinds of design and implementation issues, and resolve the same kinds of problems. MSF uses O-O analysis and design concepts, but also examines a broader business and organizational context that surrounds the development of an information system.