The concept of proxy

Basically in computer networks a proxy server is a server that acts as an intermediary for requests from clients seeking resources from the main servers. The client connects to the proxy server, requesting for a service etc.

Proxies were invented to add structure and encapsulation to distributed systems.

The below block diagram shows the working of proxy

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code for having a proxy

1 Defining the context

// defining the context first
void *context = zmq_ctx_new ();

2 Creating the frontend

void *frontend = zmq_socket (context, ZMQ_XSUB);

3 Assigning the static IP

The reason we use static IP and proxies are because they give us the freedom to add more servers / workers without the change in topology.

Let us use IP address localhost:5000 for our frontend.

zmq_connect (frontend, "tcp://localhost:5000");

and use the IP localhost:6000 for our backend where the workers / servers sit.

void *backend = zmq_socket (context, ZMQ_XPUB);
zmq_bind (backend, "tcp://localhost:6000");

4 Run the proxy until the user interrupts

We could poll the frontend and backend sockets and process the request from the clinet and service their requests via server / workers. But, with the help of zmq_proxy function we can code it in one line.

zmq_proxy (frontend, backend, NULL);