Using constraints to render websites

Contents

Introduction

Motivation

Aim and Scope

Related Work

I Modelling of the Problem

1 Description of the Problem

1.1 Personalised Content

1.2 Generating Personalised Content

1.3 Constraints to consider

2 Constraints

2.1 Introduction

2.2 Constraint Satisfaction Problems

2.3 Solution Process

2.3.1 Arc Consistency

2.4 Constrained Optimisation Problems

2.4.1 Extended Constrained Optimisation Problems

2.5 Soft Constraints

2.6 Real-time Constraint Satisfaction

2.6.1 Analysis of the Function ψ

3 Constraint Problem Model

3.1 Slots and Campaigns

3.2 Values of Campaigns

3.3 Values of Slots

3.3.1 Example

3.4 Relaxation of Constraints

3.5 Duplicate Content

3.5.1 Example

3.6 Forced Promotions

3.6.1 Example

3.7 Real-time Problem Solution

II Prototypical Implementation

4 Overview

4.1 System Architecture

4.1.1 Distributed Approach

4.1.2 Web Interface

4.1.3 Web Service

4.2 Implementation Language

4.2.1 Documentation

4.2.2 Testing

4.2.3 Packaging

4.3 Version Control System

4.4 Test Machine Setup

5 Constraint Problem Solver Library

5.1 Overview of existing Constraint Problem Solvers

5.2 Architecture

5.2.1 Domain

5.2.2 Variable

5.2.3 AbstractConstraint

5.2.4 BinaryConstraint

5.2.5 BinaryRelation

5.2.6 AllDifferentConstraint

5.2.7 TupleConstraint

5.2.8 OneOfEqualsConstraint

5.2.9 ConstraintList

5.2.10 Problem

5.2.11 Solution

5.2.12 ConstraintSolver

5.2.13 Ruby Extensions

5.3 Constraint Problem Solution

5.3.1 Solution Process

5.3.2 Modifications for Soft Constraints

5.3.3 Constraint Satisfaction with Time Limit

5.3.4 Variable and Value Ordering

5.4 Constraint Revision

5.4.1 Binary Constraints

5.4.2 All Different Constraints

5.4.3 Tuple Constraints

5.4.4 One-of-equals Constraint

5.5 Tests and Package Management

5.6 Limitations

6 Constraint Problem Solver SOAP Wrapper

6.1 Architecture

6.1.1 Library Script

6.1.2 WSDL

6.1.3 Control Scripts

6.2 Tests and Package Management

6.3 Limitations

6.4 Use of the Interface

7 Web User Interface

7.1 Architecture

7.1.1 Data Model

7.1.2 Controller

7.1.3 View

7.2 Interface to Amazon.com

7.3 Tests and Package Management

7.4 Full Example

8 Summary

8.1 Future Work

8.1.1 Constraint Model

8.1.2 Constraint Solver

8.2 Conclusion

III Appendix

A Performance Evaluation of Consistency Algorithms

A.1 Binary Constraints

A.1.1 Methodology

A.1.2 Results

A.2 All Different Constraints

A.2.1 Methodology

A.2.2 Results

A.3 The Difference All Different makes

B Effectiveness of Real-time Constraint Satisfaction

B.1 Methodology

B.2 Results

B.2.1 Time Limit after first Solution

B.2.2 Time Limit before first Solution

C Installation Instructions and Software Versions

C.1 General

C.2 Constraint Problem Solver Library

C.3 Constraint Problem Solver SOAP Wrapper

C.4 Web User Interface

Research Objective and Core Topics

The primary research objective of this thesis is to demonstrate the feasibility of using constraint programming to generate personalised websites dynamically. The work addresses the increasing complexity of website design by modelling the rendering process as a constraint satisfaction and optimisation problem, ensuring that tailored content is delivered to customers efficiently within real-time constraints.

• Application of Artificial Intelligence techniques to dynamic web content generation.
• Modelling of complex constraints such as duplicate content prevention, page value maximisation, and real-time response requirements.
• Development of a prototypical constraint solver library implemented in Ruby.
• Integration of the solver with web services via SOAP for distributed architecture.
• Performance evaluation of consistency algorithms and real-time constraint satisfaction effectiveness.

Excerpt from the Publication

Summary of Chapters

1. Description of the Problem: This chapter introduces the challenges of website personalisation and the necessity for dynamic content generation, defining key constraints for online retail environments.

2. Constraints: This section establishes the theoretical foundations of constraint satisfaction and optimisation problems, including formal definitions and algorithms for consistency.

3. Constraint Problem Model: This chapter translates the identified web-rendering requirements into a formal constraint model, introducing concepts like slot-campaign associations and duplicate content prevention.

4. Overview: This chapter details the architectural design of the prototypical implementation, focusing on the integration of the solver, the SOAP wrapper, and the web interface.

5. Constraint Problem Solver Library: This chapter explains the internal logic and object-oriented implementation of the custom constraint solver library in Ruby.

6. Constraint Problem Solver SOAP Wrapper: This chapter describes the technical implementation of the SOAP-based web service that exposes the solver's functionality to external clients.

7. Web User Interface: This chapter introduces the front-end application built with the Camping framework, which demonstrates the end-to-end rendering of personalised website components.

8. Summary: This concluding chapter reviews the achievements of the thesis, discusses limitations, and suggests directions for future research in real-time constraint satisfaction.

Keywords

Constraint Programming, Artificial Intelligence, E-Commerce, Website Personalisation, Constraint Satisfaction, Optimisation, Dynamic Web Rendering, SOAP, Ruby, Real-time Systems, Consistency Algorithms, Constraint Modelling, User Interface, Web Services, Software Architecture

Frequently Asked Questions

What is the core focus of this research?

The research focuses on applying Artificial Intelligence techniques, specifically constraint programming, to solve the complex problem of generating personalised content for online retailer websites in real-time.

What are the primary challenges addressed by this work?

The work addresses challenges such as ensuring content variety (no duplicates), improving recommendation relevance, maximising the business value of displayed content, and adhering to strict real-time rendering constraints.

What is the primary goal of the system presented?

The goal is to provide a proof-of-concept and prototypical implementation of a system capable of assembling web content dynamically based on specific constraints relevant to each individual user session.

Which methodologies were employed?

The author developed a custom constraint solver library from scratch in Ruby, employing algorithms for constraint propagation, arc consistency, and soft constraints to handle optimisation tasks.

What does the main body of the thesis cover?

The body covers problem modelling, theoretical background of constraint satisfaction, implementation details of a dedicated solver library, development of a SOAP-based wrapper, and a web-based user interface for demonstration.

What define the main keywords of this work?

Key terms include Constraint Programming, E-Commerce, Personalisation, Optimisation, Real-time Satisfaction, and Web Service Architecture.

How is the performance of the implemented solver evaluated?

The performance is evaluated through extensive benchmarking in the appendix, comparing different consistency algorithms (like binary decomposition vs. hyper-arc consistency) across various problem sizes and types.

How does the system handle time-critical website rendering?

The system incorporates a "real-time constraint satisfaction" mechanism that drops constraints based on their priority and cost as the available computing time nears its limit, ensuring a result is always produced.