Microsoft Windows Communication Foundation: Hands-on - page 17

Chapter 3. Data Representation

In This Chapter

• Background

• XmlSerializer and XmlFormatter

• The XML Fetish

• Using the XmlFormatter

• Exception Handling

Background

The Windows Communication Foundation provides a language, called the Service Model , for modeling software communications. Software executables can be generated from models expressed in that language using the classes of a lower-level programming framework called the Channel Layer .

In the language of the Service Model, a piece of software that responds to communications over a network is a service . A service has one or more endpoints to which communications can be directed. An endpoint consists of an address , a binding , and a contract .

The role of the address component is simple. It specifies a unique location for the service on a network in the form of a uniform resource locator.

The binding specifies the protocols for communication between the client and the server. Minimally, the binding must specify a protocol for encoding messages and a protocol for transporting them.

A contract specifies the operations that are available at an endpoint. To define a contract, one merely writes an interface in one's preferred .NET programming language, and adds attributes to it to indicate that the interface is also a Windows Communication Foundation contract. Then, to implement the contract, one simply writes a class that implements the .NET interface that one has defined.

This contract was used to define the operations of a derivatives calculator service in Chapter 2, "The Fundamentals."

using System;
using System.Collections.Generic;
using System.ServiceModel;
using System.Text;

namespace DerivativesCalculator
{
    [ServiceContract]
    public interface IDerivativesCalculator
    {
        [OperationContract]
        decimal CalculateDerivative(
            string[] symbols,
            decimal[] parameters,
            string[] functions);

      void DoNothing();
    }
}

string[] symbols = new string[]{"MSFT"};
decimal[] parameters = new decimal[]{3};
string[] functions = new string[]{"TechStockProjections"};

IDerivativesCalculator proxy =
  new ChannelFactory<IDerivativesCalculator>("CalculatorEndpoint").
  CreateChannel();
proxy.CalculateDerivative(symbols, parameters, functions);
((IChannel)proxy).Close();

proxy.CalculateDerivative(symbols, parameters, functions);