Websocket

Apache TinkerPop 的 Gremlin Server 使用 Websocket 或者是 HTTP 協定與 client 溝通。 如果是 Websocket，使用的指令如下：

bin/gremlin-server.sh conf/gremlin-server-classic.yaml

而使用者可以透過 Websocket 傳送 script string 給 Gremlin Server 執行，並且取得執行的結果。

Tcllib 提供了 websocket server 與 client 的實作，這裡測試 client 的部份。 下面就是使用 Tcl 寫的測試程式（改寫自 Tcllib 文件的範例）：

package require websocket
package require uuid
::websocket::loglevel debug

proc handler { sock type msg } {
    switch -glob -nocase -- $type {
        co* {
            puts "Connected on $sock"
        }
        te* {
            puts "RECEIVED: $msg"
        }
        cl* -
        dis* {
        }
    }    
}

proc test { sock } {
    puts "[::websocket::conninfo $sock type] from \
          [::websocket::conninfo $sock sockname] to \
          [::websocket::conninfo $sock peername]"

    set id [::uuid::uuid generate]
    set msg "{\"requestId\":\"$id\",
              \"op\":\"eval\",
              \"processor\":\"\",
              \"args\":{\"gremlin\":\"g.V(x).out()\",
                        \"bindings\":{\"x\":1},
                        \"language\":\"gremlin-groovy\"}}"

    ::websocket::send $sock text $msg
}

set sock [::websocket::open ws://localhost:8182/gremlin handler]
after 400 test $sock
vwait forever

Gremlin server 除了支援 TEXT type 的訊息，也支援 BINARY type 的訊息，下面是相關的測試：

package require websocket
package require uuid
::websocket::loglevel debug

proc handler { sock type msg } {
    switch -glob -nocase -- $type {
        co* {
            puts "Connected on $sock"
        }
        bi* {
            puts "RECEIVED: $msg"
            set ::received 1
        }
        cl* -
        dis* {
        }
    }    
}

proc test { sock } {
    puts "[::websocket::conninfo $sock type] from \
          [::websocket::conninfo $sock sockname] to \
          [::websocket::conninfo $sock peername]"

    set id [::uuid::uuid generate]
    set msg "{\"requestId\":\"$id\",
              \"op\":\"eval\",
              \"processor\":\"\",
              \"args\":{\"gremlin\":\"g.V(x).out()\",
                        \"bindings\":{\"x\":1},
                        \"language\":\"gremlin-groovy\"}}"
    set mimetype "application/json"
    set length [binary format c [string length $mimetype]]
    set finalmsg [string cat $length $mimetype $msg]

    ::websocket::send $sock binary $finalmsg
}

set sock [::websocket::open ws://localhost:8182/gremlin handler]
after 400 test $sock
set received 0
vwait received
after 100
::websocket::close $sock 1000