The article "Threading and Concurrency" discusses asynchronous processing and parallelization in Java EE with EJB 3.1 (@Asynchronous and timers), Servlets and even with a JCA connector implementation.
Web Apps, SPA, PWA with vanilla Java Script (ES 6+), CSS 3 and WebStandards only. As simple as possible, but not simpler. See you at: (Progressive) Web apps, Single Page Apps and WebStandards airhacks workshops at MUC airport, Winter Edition
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