WCF stands for Windows Communication Foundation (WCF) and is a part of .NET Framework 3.0 which is considered as the Microsoft Service-Oriented Architecture (SOA) platform for building distributed and interoperable applications. WCF unifies ASMX, Remoting, and Enterprise Services stacks and provides a single programming model. WCF services are interoperable and support all the core Web services standards. 

WCF provides a set of pre-defined endpoints known as Standard Endpoints for metadata exchange, discovery and web. You can configure the standard endpoints by using a config file and programmatically. Here is the list of standard endpoints :

1. mex Endpoint
2. web Http Endpoint
3. webScript Endpoint
4. workflowControl Endpoint
5. announcement Endpoint
6. discovery Endpoint
7. udpAnnouncement Endpoint
8. udpDiscovery Endpoint

1. Address – The address where the WCF Service is hosted. In other words, what is the location of the service? An address could be an IP Address, server name, URL, and so on.
2. Binding – The binding that decides the protocol, message encoding, and security to use. Binding also decides whether to use reliable messaging and transaction support. That means it’s all about how the messages are handled on the service side and the client-side.
3. Contract – The service contract defines what service operations are available as part of that service to the client for consumption.

So, the Address (A), Binding (B), and Contract (C) are called the ABC of the service endpoint. To reach an endpoint, the Address (Where), the Binding (How) and the Contract (What) are really important for establishing communication.

When a request has made to service, it creates a new instance of service for each method call and this will be disposed of once the response goes to the client. This whole process is known as per call instance mode.

You need at least a managed process, a ServiceHost instance and an Endpoint configured for hosting a WCF service.

Following are the possible approaches for hosting a service:

• Hosting in a Managed Application/ Self Hosting:
• Console Application
• Windows Application
• Windows Service
• Hosting on Web Server
• IIS 6.0 (ASP.NET Application supports only HTTP)
• Windows Process Activation Service (WAS)

You can generate proxy by using the following steps:

Using Visual Studio

Using SvcUtil

• When a client made a request to a service, it will wait until it gets the response back.
• If the response is not received until the given time, it will show an error.
• If the client gets the response then next instructions will be executed.

WCF supports the following transport schemas:

• HTTP
• TCP
• PEER network
• IPC (Inter Process Communication)
• MSMQ

WCF Data Services uses OData (Open Data Protocol) protocol for querying or manipulating the data. WCF Data Services is built on top of WCF REST Services. It is a RESTful service to support CRUD operations on the database using the HTTP protocol. It supports all database operations using URI. DATA protocol can expose data from the relational database, File systems, Web sites, services etc. It supports XML or JSON format for exposing the data.

There are two ways to create a WCF Client or calling a WCF Service as:

• WCF Proxy
• Channel factory

There are four ways of hosting a WCF service.

• Self-Hosting
• Windows services hosting
• IIS hosting
• Windows Activation Services hosting (WAS)