# Portable Sensor System for Registration, Processing and Mathematical Analysis of PPG Signals
## 2 Portable Sensor System for Registration, Processing and Analysis of PPG Signals
### A Serverless Web Application for Processing and Analyzing Photoplethysmographic Signals  
In this work, the preprocessing and mathematical analysis of registered PPG signals with the developed experimental portable device is performed while using a web-based application through the application of Amazon serverless technology. In the serverless model, Amazon Web Services (AWS) cloud provider provides fully managed end-user computing and storage services. The services use servers, regardless of the name, and the developer abstracts these servers. In this way, the configuration and management of the underlying architecture are done by the cloud provider, not by the web application developer. The web application runs on servers, with AWS taking full control of them. This eliminates the need for resource allocation, scale, and server support for running applications, databases, and storage systems. While using serverless architecture, developers can focus on creating the web application without having to manage the servers or take the time to maintain them when running in the cloud or locally [43; 44; 45; 46].  
Creating web applications while using a serverless architecture as compared to traditional web applications has the following main advantages [47; 48; 49]:  
Scalability: Serverless architecture provides automatic scaling as the number of users while using the application increases or decreases. In a private or public cloud environment, it is possible to configure it, so that new computing instances are provisioned when there is an increase in demand. However, this usually takes some time to happen, which could potentially lead to users not being able to access the application and ultimately provide an unsatisfactory experience. Conversely, serverless applications can handle bursts of traffic by design, so no adjustments need to be made to handle intermittent traffic.  
Cost-efficiency: One of the biggest benefits in implementing a serverless architecture is that the modal of paying for the computing power that is needed is taken to the next level. In a traditional cloud computing setup, server instances can be brought up or terminated based on the level of traffic to the application and costs are only accrued for running instances. In a serverless model, this is granularized further, so the costs are associated to the number of requests to the web application and the amount of stored data. This means that if there are no new requests are sent to it, the application is essentially running for free.  
Development: A serverless implementation requires no time to be spent on managing the underlying architecture. The developers need to only focus on creating the logic required for the application, as they can just bundle it and its dependencies in serverless functions and invoke them when needed. In contrast, in a traditional web-application, the code would need to be deployed to a server that needs to be correctly provisioned and managed. Serverless is growing faster than any other cloud service with developing efficiency as one of the main reasons for its fast adoption rate.