What are the real world use case of proxy design pattern?

The Proxy Design Pattern provides a surrogate or placeholder for another object to control access to it. This can be applied in various real-world scenarios, especially when we want to add some behavior before or after
interacting with the main object. Here are some common real-world use cases:

1. Lazy Initialization (Virtual Proxy)

In scenarios where an object is resource-intensive to create (like establishing a connection to a database or loading a large file), a proxy can be used to delay the actual creation of the object until it’s truly needed.

Example:

• Image Loading: In applications where images are loaded dynamically, like a photo gallery, creating a proxy object for each image can allow placeholder images to be shown first while the real images load in the
  background only when required.

2. Access Control (Protection Proxy)

A proxy can control access to sensitive objects, restricting operations based on permissions.

Example:

• User Role-Based Access: In enterprise systems, you might use a proxy to enforce different access levels. For example, if you have a service for managing customer data, you can use a proxy to prevent users without
  sufficient permissions (like a guest user) from modifying sensitive data.

3. Remote Proxy (Network Communication)

When dealing with distributed systems, a proxy can act as a local representative for an object located on a remote server. This allows the client to interact with the remote object as if it were local.

Example:

• API Gateway in Microservices: An API gateway can act as a proxy to various backend microservices. The client interacts with the API gateway, which forwards the requests to the appropriate service, adding an extra
  layer of abstraction and sometimes handling common concerns like authentication and logging.

4. Caching Proxy

A proxy can cache the results of expensive operations, reducing load and latency for future requests.

Example:

• Web Proxy for Data Caching: In web applications, a proxy can cache HTTP responses from an API. If multiple users request the same data, the proxy can serve the cached response instead of making repeated expensive
  requests to the backend, improving response times and reducing server load.

5. Logging or Auditing (Smart Proxy)

Proxies can be used to add logging, auditing, or performance monitoring functionality around the original object.

Example:

• Method Call Logging: In systems where logging is essential for troubleshooting or audit trails, a proxy can wrap around an object and log every method call, its parameters, and its return values without modifying
  the original object.

6. Security Proxy

A proxy can ensure secure interaction with an object, possibly adding encryption or additional verification steps.

Example:

• Firewall Proxy: In network security, a proxy firewall can sit between the internal network and external clients. The proxy firewall inspects the requests coming from external clients, applying security rules before
  forwarding them to the internal systems.

These examples demonstrate the versatility of the Proxy Design Pattern in addressing various concerns, from performance optimization to security and control.