Later in Albrecht and Gaffney extended and published the method . This metric overcomes many of the limitations of the LOC sizing metric. FP measure the amount of functionality in a system by counting inputs, outputs, queries, and logical files.
Function points capture the size of an actual product and does not relate to something physical but rather to something logical that can be assessed quantitatively. FPA can be used to easily estimate the size of a software product directly from the problem specification and it measure the functionality of a program from what the user requests to system and receives in return from the system as output. The FPA is divided into following functional units ; input or set of inputs to the system, outputs from the system, request for access data or information, internal logical information, and external interface required.
Once requirements are categorized, then their respective complexity is associated with each functional requirement based on subjective judgement of the organization. LOC is simplest method ease of counting automation but can only be accurately counted when the software product is complete, while the most critical software estimations need to be performed before construction.
Software sizing using LOC is specific to the technology platform on which the application was developed, the LOC count will vary for different technology platforms. Disadvantages include difficulty of counting early in the development process, dependence on programming style, need for inflexibility in applying counting rules, and unpredictability of methods across different programming languages . FP can only be manually counted, and the estimator has to have experience to do so. Moreover, FP counting involves a degree of subjectivity.
The FP counting rules are satisfactorily well defined and codified to enable experienced FP planners to be constant in FP counts, unfortunately manual FP counting and recounting processes are unavoidably time consuming and expensive relative to automated counting. The software size measured through FP approach is independent of the technology on which the application is developed. Another advantage includes ease of generation from a clear specification and persistence across intermediate software products. With FP there is inconsistency as analysts interpret the notional constructs and the difficulty of assessing the size of embedded systems .
Other software sizing methods include use case based software sizing, which relies on counting the number and characteristics of uses cases found in a software and COSMIC which addresses sizing software that has a very limited amount of stored data such as real time systems . Use cases provide software developers with insight into software requirements . Various software sizing approaches have been proposed over the years and each of them has taken the solution of estimating software size a step further. Software size estimation is critical to providing a credible software cost estimates, thus choosing the appropriate method by which to estimate size is important.
None of these software sizing methods gives hundred percent accurate software size estimation. Software engineering research community must continue to research on reliable, accurate, and effective software sizing techniques. Improving the existing software sizing methods and introducing new methods for inputs for software cost estimation will be our future work. Galorath and Michael W. SE-9, No. Related Papers. A novel variant of function point analysis for accurate software size estimation. By Publisher ijmra. Issues in Software Cost Estimation.
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Need an account? All information managed by CM is subject to change control. Change control consists of: Identification Reporting Analysis Implementation 6.
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The change control process needs to be implemented through an appropriate change mechanism tied to who owns the information: Change control boards, which manage formal baseline products. The version description should consist of any inventory of all components by version identifier, an identification of open problems, closed problems, differences between versions, notes and assumptions, and build instructions.
Additionally, each library partition should be described by a current version description that contains the same information. Return to Top 8. Manage and Trace Requirements Practice Essentials 1. Before any design is initiated, requirements for that segment of the software need to be agreed to. Requirements tracing should be a continuous process providing the means to trace from the user requirement to the lowest level software component.
Tracing shall exist not only to user requirements but also between products and the test cases used to verify their successful implementation. All products that are used as part of the trace need to be under configuration control. Requirements tracing should use a tool and be kept current as products are approved and placed under CM. Requirements tracing should address system, hardware, and software and the process should be defined in the system engineering management plan and the software development plan.
The program needs to define and implement a requirements management plan that addresses system, hardware, and software requirements.
This plan should be linked to the SDP. All requirements need to be documented, reviewed, and entered into a requirements management tool and put under CM.
This requirements information should be kept current. The CM plan should describe the process for keeping requirements data internally consistent and consistent with other project data. Requirements traceability needs to be maintained through specification, design, code, and testing. Requirements should be visible to all project participants. Return to Top 9. All methods used to define system architecture and software design should be documented in the system engineering management plan and software development plan and be frequently and regularly evaluated through audits conducted by an independent program organization.
Software engineering needs to participate in the definition of system architectures and should provide an acceptance gate before software requirements are defined. The allocation of system architecture to hardware, software, or operational procedures needs to be the result of a predefined engineering process and be tracked through traceability and frequent quality evaluations.
All agreed to system architectures, software requirements, and software design decisions should be placed under CM control when they are approved for program implementation. All architecture and design components need to be approved through an inspection prior to release to CM. This inspection should evaluate the process used to develop the product, the form and structure of the product, the technical integrity, and the adequacy to support future applications of the product to program needs.
All system architecture decisions should be based on a predefined engineering process and trade studies conducted to evaluate alternatives. The DEVELOPER should ensure that the system and software architectures are developed and maintained consistent with standards, methodologies, and external interfaces specified in the system and software development plans.
Software engineers need to be an integral part of the team performing systems engineering tasks that influence software. Systems engineering requirements trade studies should include efforts to mitigate software risks. System architecture specifications need to be maintained under CM. The system and software architecture and architecture methods need to be consistent with each other. System requirements, including derived requirements, need to be documented and allocated to hardware components and software components. The requirements for each software component in the system architecture and derived requirements need to be allocated among all components and interfaces of the software component in the system architecture.
Return to Top All data and database implementation decisions should considerinteroperability issues and, as interoperability factors change, these decisions should be revisited. Program standards should exist for database implementation and for the data elements that are included. These standards should include process standards for defining the database and entering information into it and product standards that define the structure, elements, and other essential database factors. All data and databases should be structured in accordance with program requirements, such as the DII COE, to provide interoperability with other systems.
All databases shared with the program need to be under CM control and managed through the program change process. Databases and data should be integrated across the program with data redundancy kept to a minimum. All data and databases should be structured in compliance with DII COE to provide interoperability with other systems.
Unnecessary data redundancy should be reduced to minimum. Data and databases should be integrated as much as possible. Define and Control Interfaces Practice Essentials 1.
Before completion of system-level requirements, a complete inventory of all external interfaces needs to be completed. All external interfaces need to be described as to source, format, structure, content, and method of support and this definition, or interface profile, needs to be placed under CM control. Any changes to this interface profile should require concurrence by the interface owners prior to being made. Internal software interfaces should be defined as part of the design process and managed through CM.
Interfaces should be inspected as part of the software inspection process. Each software or system interface needs to be tested individually and a test of interface support should be conducted in a stressed and anomalous test environment.
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All internal and external interfaces need to be documented and maintained under CM control. Changes to interfaces require concurrence by the interface owners prior to being made. Milestones related to external interfaces should be tracked in the project activity network. Subsystem interfaces should be controlled at the program level.