HTTP 102 Processing (WebDAV)

Overview

HTTP 102 Processing status code is an informational response indicating that the server has received and is processing the request but no response is available yet. This status code is part of the WebDAV extension of HTTP.

Purpose

The primary purpose of the HTTP 102 Processing response is to prevent the client from timing out and assuming the request was lost. It is particularly useful for requests that take a long time to process, ensuring the client remains informed about the ongoing processing.

Usage

Client Behavior:

1. Initial Request: The client sends a request that may take a long time to process.
2. Awaiting Response: The client waits for a response from the server, understanding that processing may take time.

Server Behavior:

1. Receiving Request: The server receives and begins processing the request.
2. Sending Interim Response: The server sends a 102 Processing status to inform the client that processing is underway.
3. Final Response: Once processing is complete, the server sends the final response.

Scenarios

• WebDAV Requests: In WebDAV operations, where requests like file copying or moving can take a considerable amount of time.
• Long-Running Processes: For any HTTP request that requires more time to process, such as generating complex reports or performing server-side calculations.

Sequence Diagram

sequenceDiagram
    participant Client
    participant Server

    Note over Client: Step 1: Client sends a long-running request
    Client->>Server: POST /long-running-process HTTP/1.1 (Step 1)

    Note over Server: Step 2: Server acknowledges and starts processing
    Server->>Client: HTTP/1.1 102 Processing (Step 2)

    Note over Server: Step 3: Server completes processing
    Server->>Client: HTTP/1.1 200 OK (Final Response) (Step 3)

Curl Request Example for HTTP 102 Processing

While the HTTP 102 Processing status code is not commonly used in standard HTTP requests and is more relevant to WebDAV operations, here’s a hypothetical Curl request example that might expect a 102 Processing response in a long-running operation scenario:

# Hypothetical Curl request to a resource that might take long to process
curl -i -X POST http://example.com/long-running-process

# In a situation where the server takes time to process the request,
# it might respond initially with
HTTP/1.1 102 Processing

PHP cURL Request and Response Example for HTTP 102 Processing

While it’s uncommon to encounter an HTTP 102 Processing response in typical web applications, PHP cURL can be used to handle such responses in scenarios like WebDAV operations or other long-running processes. Here’s a hypothetical example of how this might be implemented:

<?php
// Initialize cURL session
$ch = curl_init('http://example.com/long-running-process');

// Set cURL options
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

// Execute cURL session
$response = curl_exec($ch);
$httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);

// Check for HTTP 102 Processing response
if ($httpCode == 102) {
    echo "Received HTTP 102 Processing response.\n";
    // Additional code to handle the interim response
} else {
    echo "Final response received with status code: " . $httpCode . "\n";
}

// Close cURL session
curl_close($ch);
?>

Python Request and Response Example for HTTP 102 Processing

While HTTP 102 Processing is an uncommon status code in typical web applications, it can be encountered in scenarios involving WebDAV or long-running requests. Below is a hypothetical example of how you might handle such a response using Python’s requests library:

import requests

# Example URL for a hypothetical long-running process
url = 'http://example.com/long-running-process'

# Sending a POST request to the server
response = requests.post(url)

# Checking if the response status code is 102 (Processing)
if response.status_code == 102:
    print("Received HTTP 102 Processing response")
    # Additional handling for the interim response
else:
    print(f"Response status code: {response.status_code}")

# Additional code to handle the final response

Apache Configuration for Applications That Might Use HTTP 102 Processing

Apache, by itself, does not directly generate an HTTP 102 Processing response. However, it can be configured to proxy requests to an application that might return such a response. Below is an example of how you might configure Apache as a reverse proxy to an application capable of returning HTTP 102 responses:

# Apache Configuration Example for Reverse Proxying to an Application
<VirtualHost *:80>
    ServerName example.com

    # Reverse Proxy Configuration
    ProxyRequests Off
    ProxyPass /app http://appserver.example.com/
    ProxyPassReverse /app http://appserver.example.com/

    # Logging and other directives...
    ErrorLog ${APACHE_LOG_DIR}/error.log
    CustomLog ${APACHE_LOG_DIR}/access.log combined
</VirtualHost>

NGINX Configuration for Applications That Might Use HTTP 102 Processing

NGINX can be set up as a reverse proxy to an application server that may return an HTTP 102 Processing response. This is particularly relevant for applications involved in long-running processes. Below is a sample NGINX configuration for such a scenario:

# NGINX Configuration Example for Reverse Proxying to an Application
server {
    listen 80;
    server_name example.com;

    # Reverse Proxy Configuration
    location /app {
        proxy_pass http://appserver.example.com/;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;

        # Additional proxy settings...
    }

    # Logging and other directives...
    access_log /var/log/nginx/access.log;
    error_log /var/log/nginx/error.log;
}

HTTP 101 Switching Protocols HTTP 200 OK