sockets - Rebol世界上最小的Http服务器: why first wait listen-port?

Question

在这段代码中

web-dir: %./www/   ; the path to rebol www subdirectory

listen-port: open/lines tcp://:80  ; port used for web connections
buffer: make string! 1024  ; will auto-expand if needed

forever [
    http-port: first wait listen-port

    while [not empty? client-request: first http-port][
        repend buffer [client-request newline]
    ]
    repend buffer ["Address: " http-port/host newline] 

    parse buffer ["get" ["http" | "/ " | copy file to " "]]

    parse file [thru "." [
            "html" (mime: "text/html") |
            "txt"  (mime: "text/plain")
        ]
    ]

    data: read/binary web-dir/:file

    insert data rejoin ["HTTP/1.0 200 OK^/Content-type: " mime "^/^/"]
    write-io http-port data length? data              

    close http-port
]

为什么先入

http-port: first wait listen-port

而不只是

http-port: wait listen-port

Answer 1

wait上的listen-port会阻塞，直到有新的客户端连接为止。一旦发生这种情况，它仅返回listen-port。然后，后续的first检索与新连接的客户端相对应的端口。此后，您将拥有两个不同的端口:listen-port(这是服务器在监听进一步连接的端口)和http-port(这是用于与新连接的客户端进行通信的端口)。

在这些方面，《 REBOL/Core用户指南》 2.3版中的"Creating TCP Servers"部分仍然是最新的。