A little HTTP server in Kotlin

Description

This project aims to develop a simple, but extensible framework for building TCP servers of any purpose. It comes with HTTP/1.1 by default, but it can be used with any protocol, as long as the support for it is implemented.

Features

Server features:

• Event-based processing (based on Interruptible Tasks)
• Secure TLS Sockets (with HTTPS)
• Slowloris-proof and handles many connections well

HTTP implementation features:

• GZIP response compression
• HTTP Proxy
• Static resources support
• URL aliasing support
• Exception Mappers for global exception mapping support

Sample configuration

See Example.kt

fun main() {
    // bind plain TCP on 8080, use HTTP
    bindTCP(port = 8080, protocol = Http) {
        // use HTTP 1.1 on this port
        useHttp11()
        // use GZIP
        withResponseWriter(GZipResponseWriter())

        // configure /* mapping
        url(index("/")) {
            // a static index of classpath resources
            staticIndex("classpath:/")
        }

        // configure /example mapping
        url(exact("/example")) {
            // a static page
            staticPage("classpath:/index.html")
        }
   
        // configure /proxy mapping
        url(exact("/proxy")) {
            // a proxy of https://httpbin.org
            proxy("https://httpbin.org/")
        }

        // make / an alias of /index.html
        alias(exact("/") to "/index.html")
    }.start() // start server on port 8080

    // bind secure TCP on 8443, use HTTP and a self signed certificate
    bindSecureTCP(
            port = 8443,
            protocol = Http,
            serverCertificate = selfSignedCertificate()
    ) {
        // use HTTP 1.1 on this port
        useHttp11()

        // configure /* mapping
        url(index("/")) {
            // a static index of classpath resources
            staticIndex("classpath:/")
        }

        // configure /proxy mapping
        url(exact("/proxy")) {
            // a proxy of https://httpbin.org
            proxy("https://httpbin.org/")
        }

        // make / an alias of /index.html
        alias(exact("/") to "/index.html")
    }.start() // start server on port 8443
}

Project Modules

ksockserver-example

This is an example usage of the ksockserver. It contains one Kotlin file, which starts the application on ports 8080 and 8443 (SSL). There are the following endpoints available:

• / or /index.html - a sample HTML file
• /proxy - a proxy to https://httpbin.org/
• /example (8080 only) - a static resource (HTML file)

ksockserver-dispatcher

This module contains the logic of managing the socket and handling connections. There are socket configuration classes and dispatchers for plain TCP and secure TCP sockets.

ksockserver-http-core

The ksockserver-http-core module contains the base models and interfaces used in HTTP-related libraries, and it also contains a few common helper functions.

ksockserver-http-server

This module relies on ksockserver-http-core and ksockserver-dispatcher and it contains the logic of handling reading of HTTP requests, mapping URLs to resource handlers and writing HTTP responses. It also handles the exceptions during request processing and maps them according to registered ExceptionMappers

ksockserver-static-pages

In this module there is logic that handles reading files and serving them as static resources. It is meant to be used with a ksockserver-http-server.

ksockserver-http-gzip

This little module enables GZip compression algorithm in HTTP responses.

ksockserver-http-proxy

This module is used to configure a URL mapping as a proxy of another HTTP(S) application.