The relationship between BizTalk and WCF

So, are WCF and BizTalk Server competing technologies or complementary ones? Let's review the role of each:

BizTalk Server 2013

Enterprise offering for messaging solutions that require consistent life cycle for design, build, and deployment Process orchestration made available through a stateful, durable workflow engine Adapters to numerous protocols, technologies, and line-of-business systems Route data through high-performing, scalable, and persistent publish-subscribe message broker Runtime services with built-in scalability and load balancing Supplementary modules such as Business Activity Monitoring, Single Sign On, and Business Rules Engine

Windows Communication Foundation

Unify existing .NET communication technologies under a single umbrella Offer rich cross-platform support for WS* extensions targeting security, transactions, and stateful sessions Variety of flexible service host containers available Significant amount of service configuration...