The document discusses stream processing and analytics using Flink for four kinds of analytics: on-demand aggregation and pattern detection, clustering, forecasting, and pattern detection on geo-temporal data. It describes building a unified stream processing architecture on Flink to support these analytics use cases by developing shared abstractions for multi-dimensional geo-temporal data and a geotemporal API. Examples of building forecasting applications on this architecture are provided. Key lessons learned include ensuring robust infrastructure, optimizing for single-node scaling, achieving exactly-once processing through proper data modeling, using external state storage, and standardizing monitoring.