#lang racket ;; New imports: (require xml net/url) ;; No changes to `serve' or `accept-and-handle'... (define (serve port-no) (define main-cust (make-custodian)) (parameterize ([current-custodian main-cust]) (define listener (tcp-listen port-no 5 #t)) (define (loop) (accept-and-handle listener) (loop)) (thread loop)) (lambda () (custodian-shutdown-all main-cust))) (define (accept-and-handle listener) (define cust (make-custodian)) (parameterize ([current-custodian cust]) (define-values (in out) (tcp-accept listener)) (thread (lambda () (handle in out) (close-input-port in) (close-output-port out)))) ;; Watcher thread: (thread (lambda () (sleep 10) (custodian-shutdown-all cust)))) ;; The `handle' function now parses the request into `req', and it ;; calls the new `dispatch' function to get the response, which is an ;; xexpr instead of a string. (define (handle in out) (define req ;; Match the first line to extract the request: (regexp-match #rx"^GET (.+) HTTP/[0-9]+\\.[0-9]+" (read-line in))) (when req ;; Discard the rest of the header (up to blank line): (regexp-match #rx"(\r\n|^)\r\n" in) ;; Dispatch: (let ([xexpr (dispatch (list-ref req 1))]) ;; Send reply: (display "HTTP/1.0 200 Okay\r\n" out) (display "Server: k\r\nContent-Type: text/html\r\n\r\n" out) (display (xexpr->string xexpr) out)))) ;; New: the `dispatch' function and `dispatch-table': (define (dispatch str-path) ;; Parse the request as a URL: (define url (string->url str-path)) ;; Extract the path part: (define path (map path/param-path (url-path url))) ;; Find a handler based on the path's first element: (define h (hash-ref dispatch-table (car path) #f)) (if h ;; Call a handler: (h (url-query url)) ;; No handler found: `(html (head (title "Error")) (body (font ((color "red")) "Unknown page: " ,str-path))))) (define dispatch-table (make-hash)) ;; A simple dispatcher: (hash-set! dispatch-table "hello" (lambda (query) `(html (body "Hello, World!"))))