On Building Special-Purpose Social Networks for Emergency Communication

By: Mark Allman

Appears in: CCR October 2010

Abstract: In this paper we propose a system that will allow people to communicate their status with friends and family when they find themselves caught up in a large disaster (e.g., sending "I'm fine" in the immediate aftermath of an earthquake). Since communication between a disaster zone and the non-affected world is often highly constrained we design the system around lightweight triggers such that people can communicate status with only crude infrastructure (or even sneaker-nets). In this paper we provide the high level system design, discuss the security aspects of the system and study the overall feasibility of a purpose-built social networking system for communication during an emergency.

Public Review By: S. Saroiu

This paper presents the design of a social network designed for emergency situations. In the case of a catastrophic event, each user can publish a small notification, which is then relayed to a small number of contacts. There are limits on how large a message can be and how many contacts one can list in the system. The system's goal is to send at least one notification per hour on behalf of each user.

The system's design is relatively simple. The user registers their list of contacts with a server, and receives in return a hard-to-guess ID. These contacts are then stored on a collection of tens to hundreds of servers that self-organize in a DHT. In case of emergency, a user publishes a message using their ID to the server, which in turn sends it to the user's contacts. The design also addresses the system's security needs and uses CAPTCHAS for the user registration step and the sparseness of the users' ID space to make it hard for spammers to impersonate a user.

The system's functionality is constrained. Yet, it is precisely the minimalist design of the system combined with the originality of the scenario that make the paper such an interesting read. As a user, I feel I would use such a system if it were real, and as a system designer, I see little reason for this design not to work in practice.

The reviewers had little criticism to offer to the paper. The design does not take a stance on what communication technology people will use to sign up for the system or to relay the notification messages. While the paper uses e-mail for its "back-of-the-envelope" calculations, it also leaves open the possibility of using multiple channels, such as voice calls, SMS messages, or IM messages. The reviewers also wondered what constitutes an "emergency" and whether people should be allowed to use the system in case of personal emergencies, such as in a car accident. Finally, reviewers wondered whether the paper's reluctance to make use of today's social networks (e.g., Facebook, Twitter) is warranted given these systems' popularity and ease-of-use.