How to create service in C# which will perform some operations asynchronously in scenario mentioned below? - c#-4.0

Question

I have WebApi Controller as mentioned below. This controller having Update method which will internally call service called CustomerDataService to Update Customer Records.Assume we have n customer records to update.
UpdateMethod in CustomerDataService will perform update and return the update response.
I have requirement to do some heavy processing asynchronously after the update response like manipulating data / managing the data cache. As this processing is time consuming not relevant to the consumer of this API as Update successfully happens So I have to perform this asynchronously. Can I do this with C# with the given scenario? Please suggest.
Note: I do not want to create any batch job to achieve this as I want to perform operation(s) which are user session specific.
Controller
public class CustomerController : ApiController
{
[HttpGet]
public string UpdateCustomer()
{
ICustomerService obj = new CustomerDataService();
return obj.UpdateCustomer(GetCustomerList());
}
private List<CustomerModel> GetCustomerList()
{
return new List<CustomerModel>()
{
new CustomerModel
{
CustomerId="1",
Name="John",
Category="P1"
},
new CustomerModel
{
CustomerId="2",
Name="Mike",
Category="P2"
}
//....n Records
};
}
}
Model
[Serializable]
[DataContract]
public class CustomerModel
{
[DataMember]
public string CustomerId { get; set; }
[DataMember]
public string Name { get; set; }
[DataMember]
public string Category { get; set; }
}
Interface and CustomerDataService
public interface ICustomerService
{
string UpdateCustomer(List<CustomerModel> customerList);
}
public class CustomerDataService : ICustomerService
{
public string UpdateCustomer(List<CustomerModel> customerList)
{
//Do Data Processing - DB Call
//Return Confirmation Message
return "Data Updated Successfully!!!";
//Needs to perform some processing asynchronously i.e. Call ProcessResults()
}
private void ProcessResults()
{
//DO Processing
}
}

Answer 1

What you are looking for is using async/await in c#, see this article on Microsofts website: Asynchronous Programming with Async and Await. Here is another article with plenty of examples: C# Async, Await.
Once you understand how this works it will be very easy to change your code to take advantage of this pattern. Let us know if you have specific questions or run into problems.