226 IM Used: An HTTP Status Code Indicating Instance Manipulations Have Been Used

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About 226 IM Used

Overview of 226 IM Used

Indicating Resource InstancesHTTP Status Code

226 IM Used

Overview The 226 IM Used is an HTTP status code utilized in the extended HTTP protocol, Delta Encoding in HTTP (RFC 3229). It indicates that the server has processed the client’s request using an instance manipulation method and returned a processed resource rather than the full resource.

Meaning The client’s request was successfully processed, and a processed resource was returned.

When is 226 IM Used Returned?

  • When Delta Encoding in HTTP is used to retrieve partial resources, and the server returns a processed resource based on the client’s request
  • When the server combines multiple ranges or conditions to generate the resource
  • When the client requests efficient data transfer and receives the processed result

Examples of 226 IM Used

Retrieving a Resource with Delta Encoding

GET /resource HTTP/1.1  
Host: example.com  
A-IM: vcdiff  

Response example:

HTTP/1.1 226 IM Used  
Content-Type: application/delta-vcdiff  

[binary delta-encoded data]

Explanation: When the client requests delta encoding using the A-IM header, the server may return the resource’s differential data. The 226 status code indicates that the response contains processed data rather than the full resource.

Returning Processed Results for Multiple Conditions

GET /data HTTP/1.1  
Host: example.com  
A-IM: gzip, vcdiff  

Response example:

HTTP/1.1 226 IM Used  
Content-Type: application/delta-vcdiff  

[processed data with delta encoding and gzip compression]

Explanation: When the client requests multiple instance manipulations (in this case, gzip and vcdiff), the server processes the request and returns the combined result with the 226 status code.

Points to Note

Considerations when returning 226 IM Used:

  • Verify client compatibility
    Ensure that the client supports Delta Encoding or other instance manipulation methods.
  • Maintain full compatibility
    The response data must be properly formatted to allow accurate reconstruction on the client side.

Comparison with Related HTTP Status Codes

Explanation of HTTP status codes related to 226 IM Used:

  • 200 OK: Used when returning the full resource.
  • 206 Partial Content: Used when returning a specific range of the requested resource.

Understanding these differences ensures the appropriate use of the 226 status code.