This document provides an overview of SAPO BUS, including: 1. What is SAPO BUS and its architecture? It is a middleware that implements authentication, caching, support for bindings, transformations, protection, routing and monitoring between clients and services. 2. How to develop services using a contract-first approach with SAPO BUS. This includes creating a schema, project, and service then publishing the operations and strategies. 3. Benefits of using SAPO BUS include standardized contracts, interoperability, and administrative simplification through the back office. It also generates contracts, stubs and proxies automatically.