C# network programming knowledge points that every .NET developer should master

C# network programming knowledge points that every .NET developer should master

The previous article talked about the knowledge points of C# processing file system I/O. This article will introduce the knowledge points of C# network programming. With the continuous development of information technology, network programming has become more and more important in .NET development. Whether you are building web applications, implementing real-time communications, or dealing with distributed systems, C# network programming is an essential skill. The following are the key knowledge points that .NET developers should master in network programming.

1. HTTP request knowledge points

Making HTTP requests in C# is a common task in .NET development, and using the HttpClient class is a common way. The following will introduce the relevant knowledge points of HttpClient.

1. HttpClient class

HttpClient is the main class used to send HTTP requests and receive HTTP responses. Creating an HttpClient instance is the first step in making an HTTP request.

using System.Net.Http;
 HttpClient client = new HttpClient();
 

2. Basic GET request

Use HttpClient to send a basic GET request to obtain resources on the remote server.

 //Without parameters
   string url = "https://api.example.com/data";
    HttpResponseMessage response = await client.GetAsync(url);
 // Pass query parameters in the GET request to obtain data that meets specific conditions.
 String url = "https://api.example.com/data";
 string queryString = "?param1=value1&param2=value2";
    HttpResponseMessage response = await client.GetAsync(url + queryString);
 

3. POST request

Use HttpClient to send POST requests, usually used to submit data to the server.

 string url = "https://api.example.com/data";
    HttpContent content = new StringContent("{'key':'value'}");
    HttpResponseMessage response = await client.PostAsync(url, content);
 

4. Request header settings

Set custom request headers in HTTP requests, such as authorization information, content type, etc.

 //The following case is to add token verification
   client.DefaultRequestHeaders.Add("Authorization", "Bearer token");
 

5. Processing responses

After the above GET and Post requests, the response content, status code and other information can be obtained from HttpResponseMessage.

 string responseBody = await response.Content.ReadAsStringAsync();
    HttpStatusCode statusCode = response.StatusCode;
 

6. Exception handling

Possible exceptions can be handled in the request, such as network errors, timeouts, etc., usually captured using HttpRequestException.

 try
    {
        HttpResponseMessage response = await client.GetAsync(url);
        response.EnsureSuccessStatusCode();
    }
    catch (HttpRequestException ex)
    {
 ​​​​//Handle exceptions
    }
 

7. Asynchronous request

Use an asynchronous method to send HTTP requests to avoid blocking the main thread.

 await Task.Run(async () =>
    {
        HttpResponseMessage response = await client.GetAsync(url);
        // handle response
    });
 

8. Use HttpClientFactory

Use HttpClientFactory to manage HttpClient to improve performance and resource utilization, as recommended by the official website.

string? httpClientName = builder.Configuration["TodoHttpClientName"];
 ArgumentException.ThrowIfNullOrEmpty(httpClientName);
 //Requires dependency injection before use
 builder.Services.AddHttpClient(
     httpClientName,
     client =>
     {
         client.BaseAddress = new Uri("https://api.example.com/data");
         client.DefaultRequestHeaders.UserAgent.ParseAdd("dotnet-docs");
     });
 

For details, please see the previous article: The correct way to use HttpClient in .NET Core

9. Cancel HTTP request

Use CancellationToken to cancel an ongoing HTTP request.

 var cts = new CancellationTokenSource();
     HttpResponseMessage response = await client.GetAsync(url, cts.Token);
 

10. File upload

File upload is implemented through HTTP request, and MultipartFormDataContent is set to pass the file data.

 using var form = new MultipartFormDataContent();
     form.Add(new ByteArrayContent(fileBytes), "file", "filename.txt");
     HttpResponseMessage response = await client.PostAsync(uploadUrl, form);
 

These knowledge points cover basic and advanced techniques for making HTTP requests in C#. Proficient in using this knowledge, you can easily handle various network communication-related scenarios, thereby building robust and efficient .NET applications.

Reference: learn.microsoft.com/zh-cn/dotnet/fundamentals/networking/http/httpclient

2. WebSocket communication knowledge points

WebSocket is a network transport protocol that enables full-duplex communication over a single TCP connection and is part of the OSI model.�Request forgery (CSRF)

ASP.NET MVC can use mechanisms such as Anti-Forgery Token to prevent CSRF attacks.

 @Html.AntiForgeryToken()
 

7. Authentication and authorization

Use more advanced authentication mechanisms such as JWT (JSON Web Token) and implement appropriate authorization policies in your application.

 [Authorize]
    public ActionResult SecureAction()
    {
        // safe operation
    }
 

8. Secure file upload

Verify and securely handle files uploaded by users to prevent malicious file uploads.

 if (IsFileSafe(file))
    {
        // Process uploaded files
    }
 

9. Secure Cookie Handling

Configure security settings for cookies, such as setting attributes such as HttpOnly and Secure.

 var cookie = new HttpCookie("myCookie", "value");
    cookie.HttpOnly = true;
    cookie.Secure = true;
    Response.Cookies.Add(cookie);
 

5. Conclusion

Mastering these C# network programming knowledge points is crucial for .NET developers. These knowledge points cover C# network programming skills commonly used in .NET development, helping developers build more robust and efficient network applications. In actual projects, in-depth study and practice of these knowledge points according to needs will help improve .NET developers’ capabilities in the field of network programming. There are many knowledge points in network programming, such as transmission format, RESTful architectural style, etc., which will not be listed due to limited space.

I hope the C# network programming knowledge points provided in this article will be helpful to every .NET developer. What else do you know about C# network programming knowledge points? Welcome to leave a message to discuss or complain about this article.

Reference:AI Query

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