(Note: This is a reply to Mr. G.'s thread in USeP-IC Web Forum - Assignment 4: Identify and discuss at least 3 systems development models .. discuss each phases...)
Systems development models are being used to help guide the system analyst in the planning, analysis, design, and implementation phases of software development project. These models specify how the activities of development process are organized in the total system development effort (Sharma). Here are some of the widely used models by most system analyst:
Waterfall model
The waterfall approach is the simplest system development model. Also termed as linear sequential model, the waterfall approach organizes like a waterfall – each phase of the project is organized in such a way it falls into the next phase.
Figure 1 – The waterfall model.
The model basically has the following activities: planning, analysis, design, development, testing and implementation, and maintenance. A project begins with initiation or planning where you get an overview and goals of a certain project. Requirements gathering and analysis shall follow. The next step is laying the system design and specification. After breaking down the system into pieces to analyze the situation, goals, and requirements, the system’s designs, functions, and operations shall now be described in detail. Here, the architecture, database design, structure, and other important components are defined. Coding and verification will now take place after the design step is accomplished. The system design must be translated into machine-readable code using programming languages and tools. Once the programming is done, the code generated will now be integrated and the system shall undergo testing. Testing is done to eliminate certain bugs that were committed so to make the software or system run successfully. User acceptance testing is also done alongside with unit and system testing. If successful, the system will now be installed and maintained or updated in its duration of operation.
Since the steps in the waterfall model are organized in a linear order, each phase should be done first before proceeding to the next. This kind of ordering implies that once a phase is completed and its output is validated, these outputs will be the inputs to the next phase. Freetutes.com identified these several important consequences of using a linear order of process modeling: First, to clearly identify the end of a phase and beginning of the others. Some certification mechanism has to be employed at the end of each phase. This is usually done by some verification and validation. Validation means confirming the output of a phase is consistent with its input (which is the output of the previous phase) and that the output of the phase is consistent with overall requirements of the system. In waterfall modeling approach however, you can not go back to the previous phase once you are already on the next phase. A system analyst for example, will freeze the planning specifications during the analysis stage. In the analysis stage, the analyst will have to work out everything before proceeding to the next step. These are the limitations of the waterfall approach – all requirements of the system must be identified and known beforehand and openly. This is significant since the customer or the developer has little opportunity to preview the system and it may be too late if there are specifications that are not yet mentioned or pointed out. The advantage with this kind of generic process model is that it portrays a sequential order of activities, which is beneficial in a sense for me. Even inexperienced individuals will find this easy to use and understands as it clearly defines the order of activities in a project. Its structure is also good in managing control for the project plan since it is uncomplicated to point the particular stage where the project team is currently working, for example.
Prototyping Model
This kind of model evolved a little bit improved than the waterfall approach. If the waterfall is a linear organization of activities in a system, the prototyping model seems like the cyclic version of the waterfall. Whatis.com defines the prototyping model as “a systems development method (SDM) in which a prototype (an early approximation of a final system or product) is built, tested, and then reworked as necessary until an acceptable prototype is finally achieved from which the complete system or product can now be developed.” This kind of model is a type of iterative and trial-and-error process which takes place between a user or client and a developer. Since it is often difficult to know and determine the exact requirements of the system on the first hand, the prototyping model was developed.
Just like in the waterfall process, there are also several steps which should be taken in this model. First, the requirements of the system must be identified and defined in detail as much as possible. This is the requirements definition and collection stage. The next step is the design stage. Here, a preliminary design of the system once the initial requirements or information are gathered. The first prototyping then follows, which may be constructed from the preliminary design. It will then be evaluated and reviewed by the users or client who will assess the strengths and weaknesses, takes note of what shall be added and / or what shall be removed. The developer takes note of the user ratings and the modifications of the system requirements, collects and analyzes the remarks of the users, and this will in turn create and/or modify another prototype. The second prototype will then be constructed and evaluated in the same manner as the first prototype. The second prototype will again be presented to the customer for another review and assessment, and the next step will be the prototype refinement where it is revised by the developer to be more efficient. These steps are reiterated until such time when the users are satisfied with the requirements and functionalities of the prototype representing the desired final product. Thus, after approval the final system is constructed based upon the final prototype created and modified. The final stage would be the system implementation where the final system is thoroughly evaluated and tested.
In this kind of system development process, the product undergoes several testing and iterations, revising and refining the requirements and components to meet the exact expectations of the users or clients. As we have noticed, during this type of development process model, there is much communication between the developer and the client. I guess this is the most widely used system or software development process model or methodology today. Even in school projects or simple transactions between programmers or developers and customers, prototyping is the primary approach. It is therefore not very easy to determine and comprehend the exact requirements of a system as requested by the customer. By using the prototyping technique, the customer will get to know and can have the opportunity to get the “feel” and “look” of the system. For instance, the developer can show the sample user interfaces without complete coding of the whole just to demonstrate some important functions of the system.
Spiral model
The spiral model is a kind of iterative process, combining the features of the waterfall model and the prototyping approach (software development wherein a prototype is build based on the determined requirements of the software or system project). Introduced by Barry Boehm in 1986, the phases of a spiral model are undergone in an iterative process, starting with a design goal and ends with the reviews of the client. In this case, the analysis and progress of the project are being verified step by step.
As the name implies, the activities of this development model are organized in a spiral-like structure. The radial dimension in the spiral represents the cumulative cost in accomplishing the steps while the angular dimension is said to be representing the progress made in completing each cycle of the spiral (Freetutes.com). The preliminary version of the system is being developed then repeatedly modified based on the reviews and evaluations of the customers or clients, just like in the prototyping process. Since there is a repetition, the development of the iteration begins in the center of the spiral and works outward, making more complete and improved versions of the system’s progress.
As noticed in most spiral model illustration, it is divided into four (4) main quadrants. The first quadrant shows the step of determining goals, alternative, and constraints. The activities in this quadrant involve the analysis of the project goals and objectives, investigating the possible alternatives of the system implementation, and examining the constraints and limitations imposed on the alternatives. If the analyst has a clear understanding now of the system’s objectives, alternatives, and constraints we can now proceed to quadrant two (2).
The second quadrant of the spiral model is the evaluation of the alternatives and risks. Risk assessment is included in this step as a means of evaluating the version of the system whether or not the development shall continue. If in case, the risks are hard to bear, or can not be taken, the progress of the project can be stopped. Boehm describes these activities which may involve prototyping, simulation, benchmarking, reference checking, administering user questionnaires, analytic modeling, or combination of these techniques. When risk analysis and prototyping is done, we can now go to quadrant three (3).
Developing and testing is the concentration in the third quadrant of the spiral. Activities to develop, verify next-level product are being performed. The detailed requirements are determined and the system is started coding, designed, validated, tested, and implemented. As we can see, it follows the basic waterfall approach where the concept of design, develop, and testing is employed.
Planning constitutes the fourth quadrant of the spiral. This phase includes thorough technical review and assessment of the various aspects of the development of system components, thus further evaluating the status, progress, merits, and risks associated. During this stage, the customer / client is given the opportunity to analyze the results of the previous versions created in the prior steps and through planning and managing these results they can give feedback to the developer(s) who may apply some modifications and improvements in the succeeding cycles.
I would like to acknowledge the following references:
Software Development Life Cycle (SDLC), stylusinc
http://www.stylusinc.com/Common/Concerns/SoftwareDevtPhilosophy.php
Prototyping model, Whatis.com
http://searchcio-midmarket.techtarget.com/sDefinition/0,,sid183_gci755441,00.html
Prototyping, Center for Technology in Government, University at Albany
http://www.ctg.albany.edu/publications/reports/survey_of_sysdev?chapter=7
Systems Development Life Cycle
Spiral model
from Wikipedia.org
The Spiral Life Cycle Model
Waterfall Software Development Life Cycle Model
from Freetutes.com - the free tutorial website
Survey of System Development Process Models, Center for Technology in Government in University at Albany
Sharma, Bulbul, System Development Approaches, Roll No.-12 PGDM
Waterfall model
The waterfall approach is the simplest system development model. Also termed as linear sequential model, the waterfall approach organizes like a waterfall – each phase of the project is organized in such a way it falls into the next phase.
Figure 1 – The waterfall model.
The model basically has the following activities: planning, analysis, design, development, testing and implementation, and maintenance. A project begins with initiation or planning where you get an overview and goals of a certain project. Requirements gathering and analysis shall follow. The next step is laying the system design and specification. After breaking down the system into pieces to analyze the situation, goals, and requirements, the system’s designs, functions, and operations shall now be described in detail. Here, the architecture, database design, structure, and other important components are defined. Coding and verification will now take place after the design step is accomplished. The system design must be translated into machine-readable code using programming languages and tools. Once the programming is done, the code generated will now be integrated and the system shall undergo testing. Testing is done to eliminate certain bugs that were committed so to make the software or system run successfully. User acceptance testing is also done alongside with unit and system testing. If successful, the system will now be installed and maintained or updated in its duration of operation.
Since the steps in the waterfall model are organized in a linear order, each phase should be done first before proceeding to the next. This kind of ordering implies that once a phase is completed and its output is validated, these outputs will be the inputs to the next phase. Freetutes.com identified these several important consequences of using a linear order of process modeling: First, to clearly identify the end of a phase and beginning of the others. Some certification mechanism has to be employed at the end of each phase. This is usually done by some verification and validation. Validation means confirming the output of a phase is consistent with its input (which is the output of the previous phase) and that the output of the phase is consistent with overall requirements of the system. In waterfall modeling approach however, you can not go back to the previous phase once you are already on the next phase. A system analyst for example, will freeze the planning specifications during the analysis stage. In the analysis stage, the analyst will have to work out everything before proceeding to the next step. These are the limitations of the waterfall approach – all requirements of the system must be identified and known beforehand and openly. This is significant since the customer or the developer has little opportunity to preview the system and it may be too late if there are specifications that are not yet mentioned or pointed out. The advantage with this kind of generic process model is that it portrays a sequential order of activities, which is beneficial in a sense for me. Even inexperienced individuals will find this easy to use and understands as it clearly defines the order of activities in a project. Its structure is also good in managing control for the project plan since it is uncomplicated to point the particular stage where the project team is currently working, for example.
Prototyping Model
This kind of model evolved a little bit improved than the waterfall approach. If the waterfall is a linear organization of activities in a system, the prototyping model seems like the cyclic version of the waterfall. Whatis.com defines the prototyping model as “a systems development method (SDM) in which a prototype (an early approximation of a final system or product) is built, tested, and then reworked as necessary until an acceptable prototype is finally achieved from which the complete system or product can now be developed.” This kind of model is a type of iterative and trial-and-error process which takes place between a user or client and a developer. Since it is often difficult to know and determine the exact requirements of the system on the first hand, the prototyping model was developed.
Just like in the waterfall process, there are also several steps which should be taken in this model. First, the requirements of the system must be identified and defined in detail as much as possible. This is the requirements definition and collection stage. The next step is the design stage. Here, a preliminary design of the system once the initial requirements or information are gathered. The first prototyping then follows, which may be constructed from the preliminary design. It will then be evaluated and reviewed by the users or client who will assess the strengths and weaknesses, takes note of what shall be added and / or what shall be removed. The developer takes note of the user ratings and the modifications of the system requirements, collects and analyzes the remarks of the users, and this will in turn create and/or modify another prototype. The second prototype will then be constructed and evaluated in the same manner as the first prototype. The second prototype will again be presented to the customer for another review and assessment, and the next step will be the prototype refinement where it is revised by the developer to be more efficient. These steps are reiterated until such time when the users are satisfied with the requirements and functionalities of the prototype representing the desired final product. Thus, after approval the final system is constructed based upon the final prototype created and modified. The final stage would be the system implementation where the final system is thoroughly evaluated and tested.
In this kind of system development process, the product undergoes several testing and iterations, revising and refining the requirements and components to meet the exact expectations of the users or clients. As we have noticed, during this type of development process model, there is much communication between the developer and the client. I guess this is the most widely used system or software development process model or methodology today. Even in school projects or simple transactions between programmers or developers and customers, prototyping is the primary approach. It is therefore not very easy to determine and comprehend the exact requirements of a system as requested by the customer. By using the prototyping technique, the customer will get to know and can have the opportunity to get the “feel” and “look” of the system. For instance, the developer can show the sample user interfaces without complete coding of the whole just to demonstrate some important functions of the system.
Spiral model
The spiral model is a kind of iterative process, combining the features of the waterfall model and the prototyping approach (software development wherein a prototype is build based on the determined requirements of the software or system project). Introduced by Barry Boehm in 1986, the phases of a spiral model are undergone in an iterative process, starting with a design goal and ends with the reviews of the client. In this case, the analysis and progress of the project are being verified step by step.
As the name implies, the activities of this development model are organized in a spiral-like structure. The radial dimension in the spiral represents the cumulative cost in accomplishing the steps while the angular dimension is said to be representing the progress made in completing each cycle of the spiral (Freetutes.com). The preliminary version of the system is being developed then repeatedly modified based on the reviews and evaluations of the customers or clients, just like in the prototyping process. Since there is a repetition, the development of the iteration begins in the center of the spiral and works outward, making more complete and improved versions of the system’s progress.
As noticed in most spiral model illustration, it is divided into four (4) main quadrants. The first quadrant shows the step of determining goals, alternative, and constraints. The activities in this quadrant involve the analysis of the project goals and objectives, investigating the possible alternatives of the system implementation, and examining the constraints and limitations imposed on the alternatives. If the analyst has a clear understanding now of the system’s objectives, alternatives, and constraints we can now proceed to quadrant two (2).
The second quadrant of the spiral model is the evaluation of the alternatives and risks. Risk assessment is included in this step as a means of evaluating the version of the system whether or not the development shall continue. If in case, the risks are hard to bear, or can not be taken, the progress of the project can be stopped. Boehm describes these activities which may involve prototyping, simulation, benchmarking, reference checking, administering user questionnaires, analytic modeling, or combination of these techniques. When risk analysis and prototyping is done, we can now go to quadrant three (3).
Developing and testing is the concentration in the third quadrant of the spiral. Activities to develop, verify next-level product are being performed. The detailed requirements are determined and the system is started coding, designed, validated, tested, and implemented. As we can see, it follows the basic waterfall approach where the concept of design, develop, and testing is employed.
Planning constitutes the fourth quadrant of the spiral. This phase includes thorough technical review and assessment of the various aspects of the development of system components, thus further evaluating the status, progress, merits, and risks associated. During this stage, the customer / client is given the opportunity to analyze the results of the previous versions created in the prior steps and through planning and managing these results they can give feedback to the developer(s) who may apply some modifications and improvements in the succeeding cycles.
I would like to acknowledge the following references:
Software Development Life Cycle (SDLC), stylusinc
http://www.stylusinc.com/Common/Concerns/SoftwareDevtPhilosophy.php
Prototyping model, Whatis.com
http://searchcio-midmarket.techtarget.com/sDefinition/0,,sid183_gci755441,00.html
Prototyping, Center for Technology in Government, University at Albany
http://www.ctg.albany.edu/publications/reports/survey_of_sysdev?chapter=7
Systems Development Life Cycle
Spiral model
from Wikipedia.org
The Spiral Life Cycle Model
Waterfall Software Development Life Cycle Model
from Freetutes.com - the free tutorial website
Survey of System Development Process Models, Center for Technology in Government in University at Albany
Sharma, Bulbul, System Development Approaches, Roll No.-12 PGDM
1 comment:
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Baby-sitting
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Nursery
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Diet food
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