When we talk about HTTP, one of its interesting and best features is sending and receiving conditional requests. This lets the server and client better interact with available network resources and work more efficiently. Now let's see how these requests can work and what advantages they have.
Conditional requests in HTTP allow the client to tell the server to send resources only if a specific condition is met. This can help reduce bandwidth usage and make the server lighter. For example, you might say "only send the file if it has been modified." In other cases, the server provides a specific response that indicates no need for additional resource transfers.
Using conditional requests has many benefits. For example, in the case of no content changes, repeating the request won't be sent and this can reduce pressure on the server. By reducing data traffic, users can receive faster responses and processing can be more efficient.
One of the conditional request methods is to use headers like If-Modified-Since and If-None-Match. With these headers, the server checks whether the file or data has changed since the last time the client received it.
If the data has not changed, the server sends a "304 Not Modified" response to the client.
In practice, conditional requests are a powerful tool for pulling data in bulk. By streamlining resources, users can enjoy a better user experience since the time for receiving data due to non-real-time updates may be reduced.
Now that we understand the importance and functionality of conditional requests in HTTP, let’s examine a code example using it:
GET /example.txt HTTP/1.1
Host: www.example.com
If-Modified-Since: Tue, 20 Oct 2023 07:28:00 GMT
Now let’s explain each line of this code:
The first line GET /example.txt HTTP/1.1: this HTTP request is for retrieving the file example.txt from the server.
The second line Host: www.example.com: here we specify that the request is being sent to the server www.example.com.
The third line If-Modified-Since: Tue, 20 Oct 2023 07:28:00 GMT: in this line, we tell the server that only if the file has been modified after the specified date and time, send the new file.