Windows Communication Foundation

The Windows Communication Foundation (WCF), previously known as Indigo, is a free and open-source runtime and a set of APIs in the .NET Framework for building connected, service-oriented applications. NET Core 1.0, released 2016, did not support WCF server side code. WCF support was added to the platform with support for .NET Core 3.1, .NET 5, and .NET 6 in 2022. WCF is a tool often used to implement and deploy a service-oriented architecture (SOA). It is designed using service-oriented architecture principles to support distributed computing where services have remote consumers. Clients can consume multiple services; services can be consumed by multiple clients. Services are loosely coupled to each other. Services typically have a WSDL interface (Web Services Description Language) that any WCF client can use to consume the service, regardless of which platform the service is hosted on. WCF implements many advanced Web services (WS) standards such as WS-Addressing, WS-ReliableMessaging and WS-Security. With the release of .NET Framework 4.0, WCF also provides RSS Syndication Services, WS-Discovery, routing and better support for REST services. A WCF client connects to a WCF service via an endpoint. Each service exposes its contract via one or more endpoints. An endpoint has an address (which is a URL specifying where the endpoint can be accessed) and binding properties that specify how the data will be transferred. The mnemonic "ABC" can be used to remember address/binding/contract. Binding specifies what communication protocols are used to access the service, whether security mechanisms are to be used, and the like. WCF includes predefined bindings for most common communication protocols such as SOAP over HTTP, SOAP over TCP, and SOAP over Message Queues, etc. Interaction between WCF endpoint and client is done using a SOAP envelope. SOAP envelopes are in simple XML form, which makes WCF platform-independent. When a client wants to access the service via an endpoint, it not only needs to know the contract, but it also has to adhere to the binding specified by the endpoint.