System Development Concept (Part II)

Approaches Of Developing A System

1. Classical approach and structured approach ( looked into used methodologies).

A. Classical Approach
Is classic approach methodologies to develop the system by following the step in system life cycle.

B. Structured Approach
Approach of structure provide the additional system in the form of appliances and techniques to develop the system beside fixed follow idea from system life cycle.

2. Piecemeal approach and system approach (looked into the target to reach).

A. Piecemental Approach
Piecemeal approach is a system development approach that emphasize to an activity or just the application. The selected activity or application is developed without pay the attention from the position in information system or without pay the attention from the organization target comprehensively.

B. System Approach
Approach of system, pay attention the information system as one unity integrated to each activity or his application.

3. Bottom-up approach and Top-down approach (looked into the way of determining requirement of system).

A. Bottom-Up Approach
A bottom-up approach is piecing together systems to give rise to grander systems, thus making the original systems sub-systems of the emergent system. In a bottom-up approach the individual base elements of the system are first specified in great detail. These elements are then linked together to form larger subsystems, which then in turn are linked, sometimes in many levels, until a complete top-level system is formed. This strategy often resembles a "seed" model, whereby the beginnings are small but eventually grow in complexity and completeness. However, "organic strategies" may result in a tangle of elements and subsystems, developed in isolation and subject to local optimization as opposed to meeting a global purpose.

B. Top-Down Approach
A top-down approach is essentially breaking down a system to gain insight into its compositional sub-systems. In a top-down approach an overview of the system is first formulated, specifying but not detailing any first-level subsystems. Each subsystem is then refined in yet greater detail, sometimes in many additional subsystem levels, until the entire specification is reduced to base elements. A top-down model is often specified with the assistance of "black boxes" that make it easier to manipulate. However, black boxes may fail to elucidate elementary mechanisms or be detailed enough to realistically validate the model.

4. Total-system approach andmodular approach (looked into the way of developing it).

A. Total System Approach
Total system approach is the approach which developing a system together according to comprehensive.

B. Modular Approach
Modular approach tries to divide complex system to simple some part, so that system easier will be understood and developed.

5. Great loop approach and evolutionary approach (looked into technology to be used).

A. Great Loop Approach
Great Loop Approach apply change totally at a timely use the sophisticated technology. Have the big risk because speed of change of technology.

B. Evolutionary Approach
Evolutionary approach applies sophisticated technology just for applications that need that moment and will be developed for next periods based on technology development. This approach causes investment not too expensive and can follow fast technology development.


The Meaning Of Methodology, Method And Algorithm

1. Methodology can be defined as:

• The analysis of the principles of methods, rules, and postulates employed by a discipline.
• The systematic study of methods that are, can be, or have been applied within a discipline.
• A particular procedure or set of procedures.

2. Method
Method is How to do or make something

3. Algorithm
Algorithm is a sequence of finite instructions, often used for calculation and data processing.

Classifications Of Development Methodology

1. Functional decomposition methodologies
Functional decomposition methodologies emphasize at resolving of system into smaller subsystems, so that will be more easy to be comprehended, to be designed and applied. Which included in this methodologies is:

• HIPO (Hierarchy plus Input Process Output)
• SR (Stepwise Refinement)
• ISR (Iterative Stepwise Refinement)
• Information-Hiding

2. Data-oriented methodologies

This methodologies emphasize at characteristic of data to be processed. This methodologies is grouped into 2 class:

A. Data-flow oriented methodologies
There are the include in this group methodologies such as SADT (Structured Analysis and Design Techniques), Composite Design.

B. Data structure oriented methodologies
There are the include in this group methodologies such as JAD (Jackson's system development), W/O (Warnier/Orr).

3. Prescriptive Methodologies

This methodology usually has been provided by software maker factory. In this methodology including:

• ISDOS (Information System Design and Optimization System)
• PLEXSYS
• PRIDE
• SDM/70
• SPECTRUM
• SRES and SREM, etc.

Tools For Developing A System

The tools there are in the form of diagram and chart, such as :
• HIPO diagram, Data flow diagram, SADT, structure chart, Jackson's diagrams, etc.

Besides the tools that mention above, there are utilizes that used at all of methodology. The tools as a chart set that grouped by:

• Activity charting: to figuring activity, example: chart's substituting, flowchart, etc.
• Layout charting: to figuring layout
• Personal relationship charting: to figuring person relationship, example: organization chart, working distribution chart


Techniques Used In Developing A System

1. Project Management Technique
Project management technique is the discipline of planning, organizing and managing resources to bring about the successful completion of specific project goals and objectives.

2. Finding Fact Technique
Fact-finding is an important activity in system investigation. In this stage, the functioning of the system is to be understood by the system analyst to design the proposed system. Various methods are used for this and these are known as fact-finding techniques. The analyst needs to fully understand the current system.
The analyst needs data about the requirements and demands of the project undertaken and the techniques employed to gather this data are known as fact-finding techniques.
Various kinds of techniques are used and the most popular among them are interviews, questionnaires, record reviews, case tools and also the personal observations made by the analyst himself. Each of these techniques is further dealt in next pages.

3. Meeting Technique
During conducted system development process, oftentimes meeting performed either by developer team with user and manager.


The Differences Of Being A System Analyst And A Programmer

1. System Analyst

A systems analyst is responsible for researching, planning, coordinating and recommending software and system choices to meet an organization's business requirements. The systems analyst plays a vital role in the systems development process. A successful systems analyst must acquire four skills: analytical, technical, managerial, and interpersonal.
Basically a systems analyst performs the following tasks:

• Interact with the customers to know their requirements
• Interact with designers to convey the possible interface of the software
• Interact/guide the coders/developers to keep track of system development
• Perform system testing with sample/live data with the help of testers
• Implement the new system
• Prepare High quality Documentation

2. Programmer

A programmer is someone who writes computer software. The term computer programmer can refer to a specialist in one area of computer programming or to a generalist who writes code for many kinds of software. One who practices or professes a formal approach to programming may also be known as a programmer analyst.

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System Development Concept (Part I)

The Importance Of Developing An Information System

1. Problems existence
There is a problems from the old system.

2. Organization Growth
Because the requirement is increasing, the system needed to develop.

3. For reach the opportunities
A chance to improve the organization.

4. Instructions existence (directives)
Instruction existence is instructions from the leader or from outside organization, for example regulation of government.

The Purpose Or Goal Of Developing An Information System

1. Solving the problems
2. Reach the opportunities
3. Complete the directives that given

The Organization’s Expectations After Implementing An Information System

1. Performance
In this case, performance is Measured to use and throughput of response time.

2. Information
Increase the quality of information.

3. Economy
Increase the profit and decrease the cost.

4. Control
The Purpose of control is detect and fix the mistakes or error.

5. Efficiency
The organization must to increase the efficiency of operational.

6. Services
Increase the services of system.

The Principles Of Developing An Information System

1. Developed system for the management.
2. Developed system is a big investment
3. The development of system needs educated people.
4. There is a step or process that must be done in system development.
5. System development process must not massage.
6. Don't be afraid to cancel a project.
7. Documentation is important for guidance in system development

System Development Life Cycle Models

1. Waterfall Models



The waterfall model is a sequential development process, in which development is seen as flowing steadily downwards (like a waterfall) through the phases of Conception, Initiation, Analysis, Design (validation), Construction, Testing and maintenance.

In waterfall model, the following phases are followed in order:
1. Requirements specification
The most important task in creating a software product is extracting the requirements or requirements analysis. Customers typically have an abstract idea of what they want as an end result, but not what software should do. Incomplete, ambiguous, or even contradictory requirements are recognized by skilled and experienced software engineers at this point. Frequently demonstrating live code may help reduce the risk that the requirements are incorrect.
Once the general requirements are gleaned from the client, an analysis of the scope of the development should be determined and clearly stated. This is often called a scope document. Certain functionality may be out of scope of the project as a function of cost or as a result of unclear requirements at the start of development. If the development is done externally, this document can be considered a legal document so that if there are ever disputes, any ambiguity of what was promised to the client can be clarified.

2. Design
This Phase is process which focusing at four attributes: data structure, system architecture, interface representation, and algorithm. This phase is translate requirement process into software representation.

3. Construction
4. Integration
5. Testing and debugging
6. Installation
7. Maintenance
This Phase is system maintenance process. System possibly will experience of change after submitted to customer.

Strengths:
1. Ideal for supporting less experienced project teams and project managers, or project teams whose composition fluctuates.
2. The orderly sequence of development steps and strict controls for ensuring the adequacy of documentation and design reviews helps ensure the quality, reliability, and maintainability of the developed software.
3. Progress of system development is measurable.
4. Conserves resources.

Weaknesses:
1. Inflexible, slow, costly and cumbersome due to significant structure and tight controls.
2. Project progresses forward, with only slight movement backward.
3. Little room for use of iteration, which can reduce manageability if used.
4. Depends upon early identification and specification of requirements, yet users may not be able to clearly define what they need early in the project.
5. Requirements inconsistencies, missing system components, and unexpected development needs are often discovered during design and coding.
6. Problems are often not discovered until system testing.
7. System performance cannot be tested until the system is almost fully coded, and under-capacity may be difficult to correct.
8. Difficult to respond to changes. Changes that occur later in the life cycle are more costly and are thus discouraged.
9. Produces excessive documentation and keeping it updated as the project progresses is time-consuming.
10. Written specifications are often difficult for users to read and thoroughly appreciate.
11. Promotes the gap between users and developers with clear division of responsibility.

2. Iterative Models



Iterative and Incremental development is a cyclic software development process developed in response to the weaknesses of the waterfall model. It starts with an initial planning and ends with deployment with the cyclic interaction in between.

There is process or steps of Iterative Model :

1. Initial planning
2. Planning
3. Requirement
4. Analysis and design
5. Implementation
7. Testing
8. Evaluation

The Advantages :
1. Especially useful for resolving unclear objectives; developing and validating user requirements; experimenting with or comparing various design solutions or investigating both performance and the human computer interface.
2. Potential exists for exploiting knowledge gained in an early iteration as later iterations are developed.
3. Helps to easily identify confusing or difficult functions and missing functionality.
4. May generate spesifications for a production application.
5. Encourages innovation and flexible designs.
6. Provides quick implementation of an incomplete, but functional application


3. Spiral Models



The spiral model is a software development process combining elements of both design and prototyping-in-stages, in an effort to combine advantages of top-down and bottom-up concepts. Also known as the spiral lifecycle model, it is a systems development method (SDM) used in information technology (IT). This model of development combines the features of the prototyping model and the waterfall model. The spiral model is intended for large, expensive and complicated projects.

The steps in the spiral model can be generalized as follows:

1. The new system requirements are defined in as much detail as possible. This usually involves interviewing a number of users representing all the external or internal users and other aspects of the existing system.
2. A preliminary design is created for the new system.
3. A first prototype of the new system is constructed from the preliminary design. This is usually a scaled-down system, and represents an approximation of the characteristics of the final product.
4. A second prototype is evolved by a fourfold procedure:

1. evaluating the first prototype in terms of its strengths, weaknesses, and risks
2. defining the requirements of the second prototype
3. planning and designing the second prototype
4. constructing and testing the second prototype
   

Advantages :
The spiral model promotes quality assurance through prototyping at each stage in systems development.

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Definition of Information

Information

Information is data that processed become better form and more meaning to accept it. If data is not useful to accept it so the data cannot be referred as by information.

The quality of information

- Accurate is measured by comparing the data to actual events .Payroll information must be exact or accurate. For example the information must be simple, not confusing and true free from mistakes.

- Timeliness
The information likes real time system. Its means that the information comes to user can not be late.

- Relevance
It means the information must have advantages and useful for users.
Information is relevant if it leads to improved decision making. It might also be relevant if it reaffirms a previous decision.

Value of information is depending on 2 factor, advantages and cost.
An information has a high value if the advantages more effective than the cost to get it.

Source : Analisis dan Desain. Prof.Dr Jogiyanto HM,MBA,Akt. Penerbit Andi: Yogyakarta 2005

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Definition of System

System

There are two approaches to define the system

1. Procedure Approach

Definition of procedure by Jerry FitzGerald, Ardra F. FitzGerald and Warren D. Stallings as that :
A procedure is a good arrangement of step by step instruction, that to explane what must i do (what), who must to do it (who), when to do it (when), and how to do it (how).

Definition of System based on procedure approach is a work of network from procedures which is having a mutual connection and together to do the activity or to finish a certain target.

2. Element Approach

Definition of system based on element approach is interacted a group of elements to achieve a certain goal.

A system have definite porpuse. Some people said, meaning of a system is to reach a purpose(goal), and some people said to reach a target (objectives).


The characteristic of the system

- Components of system
An integrated a set of components for collecting, storing and communicating information.

- Boundary of system
Boundary of system is scope area between another system and environment.

- Environment
Environment means is everything outside the system boundary.

- Interface
Link between subsystems to another subsystem

- input
The Energy entered into system. Input can be the treatment input ( input maintenance) and input of signal ( input signal).be the example of in computer system, treatment input is a programe, input of signal is a data.

- output
The Result of energy is processed and classified to be output which usefull and rest of dismissal. Example of the system of computer, the hot that yielded is the rest of dismissal, while information is output which good for.

- Processing
A process from input to be output

- Goal
It’s functioning because there are limits to what it can do and how it can achieve its purpose within its environment


Classification of system
Definition 1 :
1. Abstraction system : system in the form of idea.
2. Physical system : existing system physically.
Definition 2 :
1. Natural system : the system that occur passing natural’s process , the system doesn’t made by human (circle of earth).
2. Artificial system : the system that created by human (Human-Machine System).
Definition 3 :
1. Specifics system : the system operate with attitude that can be predicted.
2. Unspecific system : the system that futures condition doesn’t be predicted.
Definition 4 :
1. Closed’s system : the system doesn’t relation and effect the outside’s environment.
2. Open’s system : the system is relation and effect the outside’s environment

Source : Analisis & Desain. Prof.Dr. Jogiyanto HM,MBA,Akt. Penerbit Andi: Yogyakarta 2005

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