Web architectures are an important asset for various large-scale web applications. Being able to handle huge numbers of users concurrently is essential, thus scalability is one of the most important features of these architectures. Multi-core processors, highly distributed backend architectures and new web technologies force us to reconsider approaches for concurrent programming in order to implement web applications and fulfil scalability demands.

This diploma thesis provides a comprehensive survey on the myriads of different concepts and techniques of concurrency inside web architectures. It incorporates research publications, hands-on reports and also regards popular programming languages, frameworks and databases. We devise an architectural model for scalable web architectures and provide separate concurrency analyses of three main components: web servers, application servers and storage backends. We examine the relations between concurrency, scalability and distributed systems and dare an outlook on the near future.