# How to Place Your Apps in the Fog -- State of the Art and Open Challenges

## TL;DR

This survey reviews current methodologies for application placement in Fog computing, highlighting algorithms, prototypes, and challenges to optimize data processing across distributed IoT and cloud resources.

## Contribution

It provides a comprehensive classification of existing models, algorithms, and open challenges in application placement within Fog computing environments.

## Key findings

- Overview of employed algorithms and open-source prototypes
- Classification based on application and infrastructure characteristics
- Identification of open challenges in application placement

## Abstract

Fog computing aims at extending the Cloud towards the IoT so to achieve improved QoS and to empower latency-sensitive and bandwidth-hungry applications. The Fog calls for novel models and algorithms to distribute multi-service applications in such a way that data processing occurs wherever it is best-placed, based on both functional and non-functional requirements. This survey reviews the existing methodologies to solve the application placement problem in the Fog, while pursuing three main objectives. First, it offers a comprehensive overview on the currently employed algorithms, on the availability of open-source prototypes, and on the size of test use cases. Second, it classifies the literature based on the application and Fog infrastructure characteristics that are captured by available models, with a focus on the considered constraints and the optimised metrics. Finally, it identifies some open challenges in application placement in the Fog.