Multiple Concurrent Post Requests

This snippet defines two classes Employee and EmployeeDto, and MultiplePostObjectRequests asynchronous method, which uses the TransformBlock and ActionBlock of TPL Dataflow to send multiple HTTP POST requests concurrently and process the responses.

Employee class: This class represents an employee with properties as Id, Name, Email, IsActive and IsDeleted. The class has a constructor, which assigns values to these properties.

EmployeeDto class: This class represents a "Data Transfer Object" variant of the Employee class. It's typically used to represent a subset of the Employee data. Its constructor assigns values to the Id, Name, Email and IsActive properties.


MultiplePostObjectRequests method: This asynchronous method sends HTTP POST requests for each Employee in a list.


It creates an HttpClient to send requests to a web API url.


It creates a TransformBlock that handles the conversion of an Employee object into JSON, and the sending of this JSON to the web API as a POST request.


It creates an ActionBlock which processes the responses from HTTP requests by calling ProcessPostResponse method.


It then links the TransformBlock to the ActionBlock using the LinkTo method. This ensures that each message passed to the TransformBlock is subsequently passed to the ActionBlock.


For each Employee in the list, it posts the Employee to the TransformBlock.


It then signals completion to the TransformBlock and awaits the completion of the ActionBlock.


ProcessPostResponse method: This method is called for each response to the HTTP POST requests where it reads the content of the response, deserializes it from JSON into an EmployeeDto object, and prints this to the console.


Here's an important thing to note. Check out the comments inside the transform block. By uncommenting the lines following the TransformBlock declaration, you can alter the behavior to send multiple requests concurrently and process all their responses in parallel by setting ExecutionDataflowBlockOptions { MaxDegreeOfParallelism = DataflowBlockOptions.Unbounded }. Please make sure your environment can handle this operation. I strongly advise to start low and build up the workload!

 

public class Employee
{
    public Guid Id { get; set; }
    public string Name { get; set; }
    public string Email { get; set; }
    public bool IsActive { get; set; }
    public bool IsDeleted { get; set; }
    
    public Employee(Guid id, string name, string email, bool isActive, bool isDeleted)
    {
        Id = id;
        Name = name;
        Email = email;
        IsActive = isActive;
        IsDeleted = isDeleted;
    }
}

public class EmployeeDto
{
    public Guid Id { get; set; }
    public string Name { get; set; }
    public string Email { get; set; }
    public bool IsActive { get; set; }
    
    public EmployeeDto(Guid id, string name, string email, bool isActive)
    {
        Id = id;
        Name = name;
        Email = email;
        IsActive = isActive;
    }
}

public static async Task MultiplePostObjectRequests(List<Employee> employees)
{
    var httpClient = new HttpClient();
    var urlToTest = "https://yourapi.com/api/test";

    // Use an ActionBlock to send HTTP requests and process them in order
    var transformBlock = new TransformBlock<Employee, HttpResponseMessage>(async employee =>
    {
        var json = JsonConvert.SerializeObject(employee);
        var stringContent = new StringContent(json, Encoding.UTF8, "application/json");
        var response = await httpClient.PostAsync(urlToTest, stringContent);
        return response;
    }
    // uncomment the two lines below to send multiple requests concurrently 
    // and process all their responses in parallel.
    //     ,
    // new ExecutionDataflowBlockOptions { MaxDegreeOfParallelism = DataflowBlockOptions.Unbounded }
    );
    
    var actionBlock = new ActionBlock<HttpResponseMessage>(async response =>
    {
        await ProcessPostResponse(response);
    });

    // Link blocks to process each employee in the list
    transformBlock.LinkTo(actionBlock, new DataflowLinkOptions { PropagateCompletion = true });

    foreach (var employee in employees)
    {
        transformBlock.Post(employee); // Send each employee to the TransformBlock
    }

    transformBlock.Complete();
    await actionBlock.Completion;
}

private static async Task ProcessPostResponse(HttpResponseMessage response)
{
    var content = await response.Content.ReadAsStringAsync();
    var employeeDto = JsonConvert.DeserializeObject<EmployeeDto>(content);

    // Print the EmployeeDto
    Console.WriteLine(JsonConvert.SerializeObject(employeeDto));
}

 

You need to have these imports:

using System.Text;
using System.Threading.Tasks.Dataflow;
using Newtonsoft.Json;
No files yet, migration hasn't completed yet!