Extended Function Point (EFP) Metrics in Software Engineering: Refining Software Size Estimation

Explore Extended Function Point (EFP) metrics, a refined approach to software size estimation, particularly for complex systems. This tutorial explains Feature Points and 3D Function Points, demonstrating how these metrics build upon Function Point Analysis (FPA) to provide more accurate estimates, especially for real-time and embedded systems.

Extended Function Point (EFP) Metrics in Software Engineering

Introduction to Feature Points and 3D Function Points

Function Point Analysis (FPA) is a method for measuring software size and complexity. Extended Function Point (EFP) metrics build upon FPA, offering more sophisticated approaches for estimating software size, particularly for complex applications like real-time and embedded systems. This tutorial will explain Feature Points and 3D Function Points, two types of EFP metrics.

Feature Points

Feature points are an extension of function points, providing a more refined measure of software size, especially for systems with high algorithmic complexity. It considers the number of algorithms used in addition to the standard FPA components (EI, EO, EQ, ILF, EIF).

Feature Points are calculated as:

FP = Count_total * [0.65 + 0.01 * Σ(f_i)] = Count_total * CAF

Where:

• Count_total is the sum of the weighted counts from the table.
• CAF (Complexity Adjustment Factor) = 0.65 + 0.01 * Σ(f_i), where Σ(f_i) is the sum of the complexity adjustment values (usually provided).

(Further details on how to calculate feature points for real-time and complex applications would be added here.)

3D Function Points

3D function points extend FPA by adding two dimensions: functional dimension and control dimension, in addition to the data dimension. This provides a more comprehensive assessment of software complexity.

1. Data Dimension: Calculated as in standard FPA (counting inputs, outputs, files, etc.).
2. Functional Dimension: Considers transformations—the processing steps transforming input data into output data.
3. Control Dimension: Considers transitions—the number of transitions between different states of the system.

The phrase "(The formula for calculating 3D function points would be added here, including how the complexity adjustment factor (CAF) is used. An example calculation for an embedded system would be included here. The example from the original text would be included in the HTML.)" refers to the process of calculating 3D function points, a method used in software sizing and estimation.

What are Function Points?

Function points are a unit of measurement used to express the size or complexity of a software application. They are based on the functionality that the software provides to the user, such as inputs, outputs, user interactions, and data processing.

3D Function Points

3D function points are an extension of traditional function points, incorporating dimensions for different factors like:

• Functional Complexity: How complex the functionality is within the software.
• Technical Complexity: The technical difficulty of implementing the system.
• Environmental Complexity: Factors such as the hardware, operating system, or network environment the software runs on.

Complexity Adjustment Factor (CAF)

The Complexity Adjustment Factor (CAF) is a modifier used in the function point calculation to adjust for different levels of system complexity. It typically involves evaluating a series of 14 general system characteristics, such as performance, security, and reusability. Based on the evaluation, a CAF value is determined, which is used to adjust the final function point count.

Example Calculation for an Embedded System

An example calculation would demonstrate how to apply the 3D function point methodology to an embedded system, which often has specific constraints like limited resources and real-time processing requirements. The example would show how each factor (functional, technical, and environmental complexity) is assessed and how the CAF modifies the overall function point count.

The full example from the original text would include the exact formulas and step-by-step calculation process for an embedded system, detailing how to consider each factor and adjust the result accordingly.