This document discusses implementing a service-oriented architecture (SOA) with the Zend Framework. It defines SOA and services, and describes how to build a service layer with domain models, data mappers, and data stores. It also covers decorating services with caching, logging, and formatting behaviors. The document shows how to expose services through JSON, XML, SOAP, and REST servers using Zend components. It discusses versioning services and notes on consumer performance and authentication/authorization when building web services.