---
title: Multi-Objective Optimization in Product Lines using Clafer
categories: moo
toc: true
...

# Introduction

Product-line engineering (PLE) is an approach to engineering a family of different products with a shared architecture and common components.
Individual product variants are characterized by a selection of features from the feature model of the product family.
Some features contribute positively or negatively to the overall quality of a variant. 
The challenge faced by product-line engineers is discovering which variants are optimal with respect to a set of objectives and what trade-offs have to be made when choosing among the optimal variants. 

Figure 1 presents a workflow for multi-objective modeling in product line engineering:

<figure>
  <img src="/img/MOOworkflow.jpg" width="650px"/>
<figcaption>Fig. 1: Multi-Objective Modeling Workflow</figcaption>
</figure>

The entire workflow is supported by Clafer Tools 0.4.2:

* In phases *Variability Modeling* and *Measurement*, we use [Clafer](https://github.com/gsdlab/clafer) for specifying the feature models, quality attributes, individual feature contributions to quality, and optimization objectives. 
  * For web-based editing, we use [ClaferIDE](https://github.com/gsdlab/ClaferIDE).
  * For analyzing the variability space, we use [Clafer Configurator](https://github.com/gsdlab/ClaferConfigurator).
* In phase *Multi-Objective Optimization*, we use [ClaferMoo](https://github.com/gsdlab/claferMooStandalone). 
* Finally, in phase *Visualization & Exploration*, we use [ClaferMoo Visualizer](https://github.com/gsdlab/claferMooVisualizer).

# Examples

For some larger examples, visit the following pages:

* [Mobile Phone Example](MobilePhone) - a running example from a paper
* [Android4 Example](Android4) - a synthetic example with four objectives
* [BerkeleyDB Example](BerkeleyDB) - a real-world example with three objectives
* [Adaptive Cruise Control](ACC) - a small realistic example
* [APU Example](APU) - APU = CPU + GPU

For an example step-by-step workflow with the Visualizer visit

* [Example workflow with the ClaferMoo Visualizer on Android4 model](Android4AnalysisWorkflow)