Qt FTP Client

Ported from Qt's SCXML FTP Client example.

This ports the state structure described in Qt's SCXML FTP Client example into a browser simulation. The panel stands in for the FTP control channel by sending server reply events and recording commands emitted by the statechart.

SCXML source

<scxml datamodel="ecmascript"
       initial="I"
       name="SimpleFtpClient"
       version="1.0"
       xmlns="http://www.w3.org/2005/07/scxml">
  <datamodel>
    <data id="commands" expr="['USER anonymous', 'PORT 127,0,0,1,12,34', 'RETR readme.txt']"/>
    <data id="commandIndex" expr="0"/>
    <data id="currentCommand" expr="''"/>
    <data id="lastReply" expr="''"/>
  </datamodel>

  <state id="I">
    <onentry>
      <send event="trace"><content expr="'Initial state: connect to the FTP control channel.'"/></send>
    </onentry>
    <transition event="control.opened" target="B"/>
  </state>

  <state id="B" initial="B_check">
    <state id="B_check">
      <transition cond="commandIndex &gt;= commands.length" target="S"/>
      <transition target="B_send"/>
    </state>
    <state id="B_send">
      <onentry>
        <assign location="currentCommand" expr="commands[commandIndex]"/>
        <send event="submit.cmd"><content expr="currentCommand"/></send>
      </onentry>
      <transition target="W"/>
    </state>
  </state>

  <state id="W">
    <onentry>
      <send event="trace"><content expr="'Waiting for server reply.'"/></send>
    </onentry>
    <transition event="reply.2xx" target="B">
      <assign location="lastReply" expr="_event.data"/>
      <assign location="commandIndex" expr="commandIndex + 1"/>
    </transition>
    <transition event="reply.3xx" target="P">
      <assign location="lastReply" expr="_event.data"/>
    </transition>
    <transition event="reply.4xx reply.5xx" target="F">
      <assign location="lastReply" expr="_event.data"/>
    </transition>
  </state>

  <state id="P">
    <onentry>
      <assign location="currentCommand" expr="'PASS'"/>
      <send event="submit.cmd"><content expr="'PASS'"/></send>
    </onentry>
    <transition event="reply.2xx" target="B">
      <assign location="lastReply" expr="_event.data"/>
      <assign location="commandIndex" expr="commandIndex + 1"/>
    </transition>
    <transition event="reply.4xx reply.5xx" target="F">
      <assign location="lastReply" expr="_event.data"/>
    </transition>
  </state>

  <final id="S">
    <onentry>
      <send event="trace"><content expr="'Success: command sequence completed.'"/></send>
    </onentry>
  </final>

  <final id="F">
    <onentry>
      <send event="trace"><content expr="'Failure: FTP server returned an error.'"/></send>
    </onentry>
  </final>
</scxml>