204 ошибка что это

Have you ever received a response from a server that left you wondering, “Where’s the content?

HTTP status codes play a crucial role in web development, providing information about the status of a request and response. Among the many status codes, the HTTP 204 status code, also known as “No Content,” holds a unique significance.

In this blog post, we will explore the HTTP 204 status code in detail, understanding its purpose, use cases, and best practices for implementation.

Short Summary

• The HTTP 204 status code, “No Content,” indicates that the server successfully processed a request but has no content to return in the response payload body.

• The HTTP 204 status code is commonly used in data manipulation operations such as deleting a resource or updating a resource without returning the updated representation.

Overview of HTTP Status Codes

HTTP status codes are three-digit numbers that provide crucial information about the outcome of a client’s request to a server.

They serve as a means of communication between the client and the server, indicating the success, failure, or specific conditions related to a request-response cycle. Each HTTP status code carries its own significance, allowing developers to understand and handle different scenarios effectively.

Explanation of HTTP Status Codes and Their Significance

HTTP status codes are categorized into five groups based on their first digit:

1. Informational (1xx): These status codes indicate that the server has received the request and is continuing to process it. They are informational in nature and rarely encountered in typical web development scenarios.

2. Success (2xx): Status codes in this group indicate that the server successfully processed the request and returned the desired HTTP response. These codes signify a successful outcome and are commonly encountered in various web interactions.

3. Redirection (3xx): Redirection status codes inform the client that further action is necessary to fulfill the request. They are used when the requested resource has been moved or requires a different location to be accessed.

4. Client Errors (4xx): Client error status codes (4xx)are returned when the server cannot fulfill the request due to a client error. These codes indicate that there was an issue with the request itself, such as invalid input or unauthorized access.

5. Server Errors (5xx): Server error status codes indicate that the server encountered an error while processing the request. These codes represent issues on the server side, such as internal server errors or service unavailability.

Introducing the HTTP 204 Status Code

The HTTP 204 status code, also known as “No Content,” is part of the success category (2xx) of HTTP status codes. Unlike most other success codes that include a response body, the HTTP 204 status code indicates that the server successfully processed the request but does not have any content to return in the response message body.

The purpose of the HTTP 204 status code is to acknowledge the successful completion of a request without sending any additional information.

It serves as a way for the server to communicate to the user agent that the requested operation was successful, without the need to include any data in the response.

Differentiating it from Other Status Codes

To better understand the unique characteristics of the HTTP 204 status code, it’s important to differentiate it from other related status codes:

1. HTTP 200 OK: The HTTP 200 status code is also a success code, indicating that the server successfully processed the request and returned the requested content in the response body. In contrast, the HTTP 204 status code represents a successful request where the server processed the operation but intentionally does not include any content in the response body.

2. HTTP 202 Accepted: The HTTP 202 status code indicates that the server has accepted the request but has not yet completed the processing. It is often used in scenarios where the request is put in a queue or scheduled for asynchronous processing. On the other hand, the HTTP 204 status code indicates immediate success and completion of the request, even if there is no content to return.

When and Why the HTTP 204 Status Code is Used?

The HTTP 204 status code is used in various scenarios where the server successfully processes a request but does not need to send any data back to the client. Here are some common use cases:

No response body

One of the defining characteristics of the HTTP 204 status code is the absence of a response body. This makes it ideal for scenarios where the server successfully completes a request but does not need to send any data back to the client.

Use in data manipulation operations

HTTP 204 is commonly used in operations where data manipulation occurs, such as deleting a resource or updating a target resource without returning the updated representation. In these cases, the success of the operation can be conveyed through the HTTP 204 status code without the need for additional data. It is also frequently used with interfaces that expect automated data transfers to be prevalent such as within distributed version control systems.

Supporting asynchronous processing

The HTTP 204 status code can be utilized in situations where the server performs an asynchronous operation on the request, acknowledging the successful receipt and initiation of the task without providing a response immediately. This allows the client to continue its operations without waiting for a response.

Serving as a success response with no additional information

In some cases, a successful request does not require any additional information beyond a confirmation of success. The HTTP 204 status code serves this purpose by indicating that the server processed the request successfully, but there is no further content to return.

Examples of HTTP 204 in Practice

To better understand the application of the HTTP 204 status code, let’s explore a few examples:

Deleting a resource

When a client sends a request to delete a resource, such as a user account, the server can respond with an HTTP 204 status code to indicate that the deletion was successful.

Updating a resource without returning the updated representation

If a client updates a resource’s metadata, but the client does not require the updated representation, the server can respond with an HTTP 204 status code, confirming the successful update without including the modified content.

Accepting a request without returning any data

In cases where a client submits data to the server, but the server does not need to return any data in response, the HTTP 204 status code can be used to acknowledge the successful receipt and processing of the request.

Handling a successful operation without a need for a response

For certain operations that do not require a response, such as clearing a cache or resetting a counter, the server can use the HTTP 204 status code to indicate success without sending any content.

Conclusion

The HTTP 204 status code, “No Content,” serves a specific purpose in web development. It indicates that the server successfully processed a request but does not have any content to return in the response body.

Unlike other success codes that include a response body, the HTTP 204 status code allows for efficient communication by acknowledging success without the need for additional data.

Understanding the HTTP 204 status code is essential for developers as it enables them to handle various scenarios effectively. By differentiating it from other status codes, developers can grasp its unique characteristics and use it appropriately in their applications.

Frequently Asked Questions

What does the HTTP 204 status code mean?

The HTTP 204 status code, also known as “No Content,” indicates that the server successfully processed the request, but there is no content to return in the response body.

It signifies that the request was completed successfully, but there is no additional data or information to be sent back to the client.

How is the HTTP 204 status code different from the HTTP 200 and HTTP201 status code?

The HTTP 200 status code, “OK,” indicates that the server successfully processed the request and returned the requested content in the response body where as The HTTP status code 201 is used to indicate that a request has been fulfilled and that a new resource has been created as a result. This code is typically used in response to a POST request that creates a new resource on the server.

In contrast, the HTTP 204 status code represents a successful request where the server intentionally does not include any content in the response body. It is used when there is no need to send data back to the client.

Is the HTTP 204 status code considered an error?

No, the HTTP 204 status code is not considered an error. It is part of the success category (2xx) of HTTP status codes.

Код ответа HTTP 204 No Content Success status показывает, что запрос выполнен успешно, но клиенту не нужно уходить со своей текущей страницы.

Это может быть использовано, например, при реализации функции «сохранить и продолжить редактирование» для вики-сайта. В этом случае запрос PUT будет использоваться для сохранения страницы, и будет отправлен ответ 204 No Content , чтобы указать, что редактор не должен быть заменен какой-либо другой страницей.

По умолчанию ответ 204 кэшируется ( заголовок ETag включен в такой ответ).

HTTP response status code 204 No Content is returned by the server to indicate that a HTTP request has been successfully completed, and there is no message body.

A 204 No Content response is cacheable by default and an ETag header is included in this case. If the default behavior needs to be overridden then the response must include the appropriate HTTP caching headers.

Usage

When the 204 No Content status code is received, it is in HTTP response to a HTTP operation such as a POST, PUT, or DELETE, where no message body is expected. In some instances, a server will instead return a 200 OK status code with no message body and a Content-Length specifier as 0.

An example of how this can be used is the result of a HTTP request generated by a user that presses a “Save» button on a form. The server commits the changes and relies on the client informing the user of success.

Depending on the operation, there are other more appropriate HTTP status codes that can be used to indicate there is no message body. For example, a conditional GET might return a 304 Not Modified status code to indicate that the resource does not have to be retrieved, and will not be present in the HTTP response.

Example

In the example, the client posts XML data to the server that defines a job to be complete. The server responds by acknowledging that the data was accepted and the job successfully completed. There is nothing significant to return to the client in the HTTP response, so the 204 No Content status code is appropriate.

Request

POST /job HTTP/1.1
Host: www.example.re
Content-Type: application/xml
Content-Length: 67
<?xml version="1.0">
<job>
  <id>125</id>
  <task>G01</task>
</job>

Response

HTTP/1.1 204 No Content

Code references

.NET

HttpStatusCode.NoContent

Rust

http::StatusCode::NO_CONTENT

Rails

:no_content

Go

http.StatusNoContent

Symfony

Response::HTTP_NO_CONTENT

Python3.5+

http.HTTPStatus.NO_CONTENT

Java

java.net.HttpURLConnection.HTTP_NO_CONTENT

Apache HttpComponents Core

org.apache.hc.core5.http.HttpStatus.SC_NO_CONTENT

Angular

@angular/common/http/HttpStatusCode.NoContent

Takeaway

HTTP response status code 204 No Content indicates that a HTTP request has been completed successfully, and any information being returned is in the HTTP headers. No message body will be present.

See also

• 304 Not Modified
• RFC 7231

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