This document discusses architectures for fraud detection applications using Hadoop. It provides an overview of requirements for such an application, including the need for real-time alerts and batch processing. It proposes using Kafka for ingestion due to its high throughput and partitioning. HBase and HDFS would be used for storage, with HBase better supporting random access for profiles. The document outlines using Flume, Spark Streaming, and HBase for near real-time processing and alerting on incoming events. Batch processing would use HDFS, Impala, and Spark. Caching profiles in memory is also suggested to improve performance.