This document provides an overview of leveraging open source integration with the WSO2 Enterprise Service Bus (ESB). The presentation discusses the need for an ESB, introduces WSO2 ESB and its relationship to Apache Synapse, highlights key features such as message routing, transformation, orchestration and protocol support, explains important concepts like mediators and sequences, discusses how WSO2 ESB can be extended and customized, addresses performance and monitoring capabilities, and provides two use case examples of applying WSO2 ESB for notification emails and aggregating responses from multiple backends.