如何使用c# WCF RESTful(即Web)服务发送CSV文件

我的任务是使用c# WCF RESTful(即Web)服务以CSV格式发送数据。目前，我有代码设置在JSON中发送数据。

如何发送CSV格式的数据?

注意:这实际上不是我正在使用的文件集。这只是一个示例，用于展示我如何构建我的服务，并帮助修改它以获得CSV输出。

IService1.cs:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.ServiceModel.Web;
using System.Text;
namespace WcfService4
{
    // NOTE: You can use the "Rename" command on the "Refactor" menu to change the interface name "IService1" in both code and config file together.
    [ServiceContract]
    public interface IService1
    {
        [OperationContract]
        [WebInvoke(
            Method = "GET", 
            UriTemplate = "employees",
            RequestFormat = WebMessageFormat.Json,
            ResponseFormat = WebMessageFormat.Json,
            BodyStyle = WebMessageBodyStyle.Bare)]
        List<Employee> GetEmployees();
    }
    // Use a data contract as illustrated in the sample below to add composite types to service operations.
    [DataContract]
    public class Employee
    {
        [DataMember]
        public string FirstName { get; set; }
        [DataMember]
        public string LastName { get; set; }
        [DataMember]
        public int Age { get; set; }
        public Employee(string firstName, string lastName, int age)
        {
            this.FirstName = firstName;
            this.LastName = lastName;
            this.Age = age;
        }
    }
}

Service1.svc.cs:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.ServiceModel.Web;
using System.Text;
using System.Net;
namespace WcfService4
{
    // NOTE: You can use the "Rename" command on the "Refactor" menu to change the class name "Service1" in code, svc and config file together.
    public class Service1 : IService1
    {
        public List<Employee> GetEmployees()
        {
            // In reality, I'm calling the data from an external datasource, returning data to the client that exceeds 10 MB and can reach an upper limit of at least 30 MB.               
            List<Employee> employee = new List<Employee>();
            employee.Add(new Employee("John", "Smith", 28));
            employee.Add(new Employee("Jane", "Fonda", 42));
            employee.Add(new Employee("Brett", "Hume", 56));
            return employee;
        }
    }
}