Log has been proven to be a very powerful data structure for addressing challenging distributed systems problems. DistributedLog is such a replicated log service that is built on top of Apache BookKeeper, providing infinite, ordered, append-only streams that can be used for building robust real-time systems. It is the foundation of Twitter’s durable real-time data pipeline, and has been used widely elsewhere at Twitter in applications including transactional database system, search ingestion pipeline, and real-time streaming data-analytics platform. In this talk, Sijie Guo will discuss what are the challenges on building durable real-time data pipeline, how they achieve it and how they use it to support different workloads with different characteristics from a strongly-consistent distributed database to a real-time data analytics pipeline.