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Client-server distinction. It sounds easy ("derp, back-end is server, front-end is client") but it's really quite a mind bender when you think about it. Take a

Client-server distinction. It sounds easy ("derp, back-end is server, front-end is client") but it's really quite a mind bender when you think about it. Take a given piece of website code in a given language. Where is it being executed? Some "front-end" techs (Node, Webpack, Uglify, etc.) will be executed invisibly on the server. Some "back-end" web techs (cookies, redirects, OPTIONS requests, TLS) enable some invisible client behavior. Some (PHP) are dual-purpose, executed in two stages, some (conditional comments) are hacks that exploit this duality. Some (OAuth2) are orchestrated dances between back-end and front-end. It's really not so simple when you think about it.

kijin 8y ago
It gets even more complicated because your server is often a client, too. Modern backend code will usually connect to databases and call REST APIs. The databases themselves might be part of a cluster. Moreover, the backend code is rarely exposed directly to the public; there's usually a proper http server sitting in front of it, and there might be another load balancer or CDN between the user and your http server. Every connection has a client and a server, and sometimes the same component plays both roles. Remembering which role(s) each component is playing in any given context is very important for security, not to mention debugging.
- aryamaan 8y ago
  Why don't people put backend + load balancer servers directly in front of the public? What all use cases are of using web servers?
  - therealdrag0 8y ago
    I'm not sure what OP meant. But for Java, your app runs inside an application server like Tomcat which handles the low level networking for you, I believe this fulfills a similar role as web servers fill for other languages like PHP. Basically these severs provide a separation of concerns and are built to be more scale-able than a naive application listening on a port for requests.

kijin 8y ago

It gets even more complicated because your server is often a client, too. Modern backend code will usually connect to databases and call REST APIs. The databases themselves might be part of a cluster. Moreover, the backend code is rarely exposed directly to the public; there's usually a proper http server sitting in front of it, and there might be another load balancer or CDN between the user and your http server. Every connection has a client and a server, and sometimes the same component plays both roles. Remembering which role(s) each component is playing in any given context is very important for security, not to mention debugging.

aryamaan 8y ago
Why don't people put backend + load balancer servers directly in front of the public? What all use cases are of using web servers?
- therealdrag0 8y ago
  I'm not sure what OP meant. But for Java, your app runs inside an application server like Tomcat which handles the low level networking for you, I believe this fulfills a similar role as web servers fill for other languages like PHP. Basically these severs provide a separation of concerns and are built to be more scale-able than a naive application listening on a port for requests.