I tried http://www.mail-archive.com/[email protected]/msg19437.html (I just changed to www.reboltutorial.com) :

do http://www.rebol.it/giesse/async-protocol.r

handler: func [port [port!] state [word! error!] /local tmp cmd] [
    if error? :state [print mold disarm state return true]
    switch state [
        connect [
            ; do HTTP request
            insert port {GET /files/2009/10/word.png HTTP/1.0^M^JHost: 
www.reboltutorial.com^M^J^M^J} 
            false
        ]
        read    [false]
        write   [false]
        close   [
            ; get data
            data: copy port
            close port
            ;print copy/part data find data "^M^J^M^J"
            data: to binary! find/tail data "^M^J^M^J"
            other/image: attempt [load data]
            other/text: ""
            show other
            false
        ]
    ]
]

port: open async://www.reboltutorial.com:80
port/awake: :handler

view layout [
    across me: box 100x100 random 255.255.255 0:00:00.5 feel [
        engage: func [f a e] [
            if a = 'time [
                me/color: random 255.255.255
                show me
            ]
        ]
    ]
    other: box 100x100 255.255.255 "Downloading image..." Return
    Area 208x100 "You can type here while downloading."
]

]

But I'm getting this error:

>> port: open async://reboltutorial.com:80
** Access Error: Invalid port spec: async://reboltutorial.com:80
** Near: port: open async://reboltutorial.com:80
>> port/awake: :handler
** Script Error: port has no value
** Near: port/awake: :handler