applied sciences Article  
SLedge: Scheduling and Load Balancing for a Stream Processing EDGE Architecture [PERSON],* (c), [PERSON], [PERSON] and [PERSON]  
1 Escuela de Informatica y Telecomunicaciones, Facultad de Ingenieria, Universidad Diego Portales, Santiago 8851169, Chile Departamento de Informatica, Universidad Tecnica Federico Santa Maria, Santiago 8940572, Chile; [EMAIL_ADDRESS] (E.R. ); [EMAIL_ADDRESS] (T.S.) Deppool of mobile devices to deploy small tasks as part of a well-known SPS called Apache Storm [2]. Mobile phones have a massive penetration in the country and are built with high computing power. Most of them are multi-core with more than 1 GB of RAM [3], so they can provide processing resources to support the processing platform. The system is based on an edge architecture. Currently, SPSs cannot integrate mobile devices and execute on edge architectures. However, some works explore the opportunity of exploiting the mobile resources to deploy operators [4; 5; 6]. It requires the design of an SPS solution that is robust and can efficiently connect the distributed hardware resources and control the network flows to facilitate real-time IoT analytics in this context. Data analysis in disaster/crisis scenarios is defiant since data traffic is highly dynamic, and processing resources may become scarce due to communication infrastructure failures. A system able to cope with these problems can greatly impact disaster preparedness, mitigation, and response phases. In 2010, Chile was hit by an 8.8 earthquake, challenging government disaster response strategies. In this scenario, social media, particularly Twitter (twitter.com; accessed on 2 May 2022), provided helpful information to coordinate the people and government response [7]. However, its impact was limited due to the lack of a specialized processing system. The importance of processing data in disaster scenarios by SLedge is also useful considering that crime is incremented in these situations. In [8], authors have proposed to process social media data to prepare police and law enforcement agencies to prevent criminal activities during and after a large crisis/disaster situation. A more recent application is related to the COVID-19 pandemic. With the unpredictability of global events, preparing a crisis management strategy at the macro-level in each country is necessary to respond to crises. In [9], authors discover critical priorities and agendas in crisis management in Saudi Arabia by grasping the most recent social issues of the COVID-19 pandemic addressed in the most trusted media sources. This research also shows how a country can use big data to detect key-social issues and then make a subsequent strategy or decision-making system to develop a public communication or new policy in future events. In this work, we propose a post-disaster application scenario in which real-time IoT analytics is performed over a fog infrastructure for face detection from a data stream generated by security cameras (see Section 3.1). This analysis can be helpful for post-disaster scenarios, securing airports, large shopping areas, and inside public transportation, among others. Literature has extensively demonstrated that social media analysis provides valuable information and can have a positive impact on the disaster phases. However, a specially suited processing system is required to cope with the challenging conditions of the scenario [10; 11]. In this context we propose SLedge (Scheduling and Load balancing for a stream processing EDGE Architecture), a low-latency system with a two-level control loop that automatically schedules SPS's tasks over connected devices and balances the load they receive, considering mobile device characteristics and preventing draining of the devices' battery. The main contribution of our work are:  
* a system model that improves resiliency specially suited for disaster/crisis scenarios,
* the model provides low-latency events processing,
* an utilization-based scheduling mechanism to balance load among processing nodes.