Web Server

Updated: 2018-12-20

Features of Web Server

  • Static file serving.
  • SSL/TLS support.
  • Virtual hosts.
  • Reverse proxying.
  • Load balancing.
  • Compression.
  • Access controls.
  • URL rewriting.
  • Custom logging.
  • Server-side includes.
  • Limited WebDAV.
  • FLV streaming.
  • FastCGI.

Forward Proxy vs Reverse Proxy

In computer networks, a reverse proxy is a type of proxy server that retrieves resources on behalf of a client from one or more servers. These resources are then returned to the client as though they originated from the proxy server itself.

  • a forward proxy acts as an intermediary for its associated clients to contact any server,
  • a reverse proxy acts as an intermediary for its associated servers to be contacted by any client.

https://en.wikipedia.org/wiki/Reverse_proxy

Event-based vs Process-based

The main advantage of the asynchronous approach is scalability. In a process-based server, each simultaneous connection requires a thread which incurs significant overhead. An asynchronous server, on the other hand, is event-driven and handles requests in a single (or at least, very few) threads.

Nginx vs Apache Http Server

  • Nginx: event-based
  • Apache: process-based

Nginx is faster at serving static files and consumes much less memory for concurrent requests. Because Nginx is event-based, it doesn't need to spawn new processes or threads for each request, so its memory usage is very low.

499 CLIENT CLOSED REQUEST

499 is a non-standard status code used by nginx: if a client closes the connection while nginx is processing the request.

E.g. if nginx is used as reverse proxy, it will wait for the backend server(e.g. uWSGI) for X seconds, after that it will respond to the client with a 504 Gateway Timeout error. If the backend server is dead or dies while nginx is waiting, nginx sees that right away and returns 499 error

Nginx Restart

$ sudo nginx -s reload

https://en.wikipedia.org/wiki/Comparisonofwebserversoftware