[Twisted-web] livepage-notification branches

11 Jul 2005

      Hello everybody.

I have been using the livepage-completion-notification-X branches of
nevow and came across an issue with Internet Explorer.  In the
liveglue.js there is a place where it tries to add some data to the
xmlhttp request object.  IE doesn't allow this.  My solution was to make
the createRequest() function return a new js object rather than the
xmlhttprequest itself.  It seems to be working, but I am not a js guru
by any stretch of the imagination so I have no idea if this is a good
way of going about solving the issue.  I'll paste my version here for
review.

##########

var liveevil_unload = false; var auto_open = true;

var base_url = this.location.toString()
var queryParamIndex = base_url.indexOf('?')
if (queryParamIndex != -1) {
    base_url = base_url.substring(0, queryParamIndex)
}
if (base_url.charAt(base_url.length-1) != '/')
  base_url += '/'

function createRequest() {
    if (window.XMLHttpRequest) {
        req = new XMLHttpRequest()
    } else {
        req = new ActiveXObject("Microsoft.XMLHTTP")
    }
    reqObj = new Object()
    reqObj.request = req
    return reqObj
}

var last_request = null
var last_server_message_time = null

function connect(outputNum) {
    var xmlhttp = createRequest()
    last_request = xmlhttp.request
    xmlhttp.request.onreadystatechange = function() {
        if (xmlhttp.request.readyState == 4) {
            if (xmlhttp.request.responseText) {
                        last_server_message_time = new Date()
                eval(xmlhttp.request.responseText)
                if (!liveevil_unload && auto_open) {
                    connect(outputNum + 1)
                }
            } else {
                last_request = null
            }
        }
    }
    xmlhttp.request.open("GET", base_url + "nevow_liveOutput?outputNum="
+ outputNum + "&client-handle-id=" + nevow_clientHandleId, true)
    xmlhttp.request.send(null)
}

var userAgent = navigator.userAgent.toLowerCase()
if (userAgent.indexOf("msie") != -1) {
    /* IE specific stuff */
    /* Abort last request so we don't 'leak' connections */
    window.attachEvent("onbeforeunload", function() { if (last_request !
= null) {last_request.abort();} } )
    /* Set unload flag */
    window.attachEvent("onbeforeunload", function() { liveevil_unload =
true; } )
} else if (document.implementation &&
document.implementation.createDocument) {
    /* Mozilla specific stuff (onbeforeunload is in v1.7+ only) */
    window.addEventListener("beforeunload", function() { liveevil_unload
= true; }, false)
}

if (auto_open) {
    connect(0)
}

var inputListeners = []
var listenerId = 0

function listener(callWhenAllDone) {
    this.listenerId = listenerId
    listenerId += 1
    this.events = []
    this.callWhenAllDone = callWhenAllDone
    this.fired = false
    this.inputDone = function(what) {
        var found = false
        for (var i in this.events) {
            if (this.events[i] == what) {
                this.events.splice(i, 1)
                found = true
                break
            }
        }
        if (this.events.length == 0) {
            if (this.fired) {
                alert("Tried to fire twice :(")
            } else {
                this.callWhenAllDone()
                this.fired = true
            }
        }
    }
}

function listenForInputEvents(callWhenAllDone) {
    var newListener = new listener(callWhenAllDone)
    inputListeners.push(newListener)
    return newListener
}

function stopListening(theListener) {
    for (var i in inputListeners) {
        if (inputListeners[i] == theListener) {
            inputListeners.splice(i, 1)
            break
        }
    }
    if (theListener.events.length == 0) {
        theListener.callWhenAllDone()
    }
}

function nevow_clientToServerEvent(theTarget, evalAfterDone) {
    if (theTarget != 'close' && liveevil_unload) {
        // Server had previously closed the output; let's open it again.
        if (auto_open) {
            liveevil_unload = false }
        connect(0)
    }
    var additionalArguments = ''
    for (i = 2; i<arguments.length; i++) {
        additionalArguments += '&arguments='
        additionalArguments += encodeURIComponent(arguments[i])
    }
    var input = createRequest()
    input.request.onreadystatechange = function() {
        if (input.request.readyState == 4) {
            eval(input.request.responseText)
            if (evalAfterDone) {
               eval(evalAfterDone)
            }
            for (var i in input.events) {
                input.events[i].inputDone(input.request)
            }
        }
    }
    input.events = []
    for (var i in inputListeners) {
        inputListeners[i].events.push(input.request)
        input.events.push(inputListeners[i])
    }
    input.request.open(
      "GET",
      base_url + "nevow_liveInput?handler-path=&handler-name=" +
      encodeURIComponent(theTarget) +
      '&client-handle-id=' +
      nevow_clientHandleId +
      additionalArguments)

    input.request.send(null)
}

function nevow_setNode(node, to) {
    document.getElementById(node).innerHTML = to;
}

function nevow_appendNode(node, what) {
    var oldnode = document.getElementById(node);
    var newspan = document.createElement('span');
    newspan.innerHTML = what;
    for (i=0; i<newspan.childNodes.length; i++) {
        oldnode.appendChild(newspan.childNodes[i]);
    }
}

function nevow_prependNode(node, what) {
  var oldnode = document.getElementById(node);
  var newspan = document.createElement('span');
  newspan.innerHTML = what;
  for (i=newspan.childNodes.length-1; i>=0; i--){
    if (oldnode.childNodes.length == 0)
      oldnode.appendChild(newspan.childNodes[i]);
    else
      oldnode.insertBefore(newspan.childNodes[i],
oldnode.childNodes[0]);
  }
}

function nevow_insertNode(node, before) {
    var oldnode = document.getElementById('before');
    var newspan = document.createElement('span');
    newspan.innerHTML = what;
    var previous = oldnode;
    for (i=0; i<newspan.childNodes.length; i++) {
        previous.parentNode.insertBefore(newspan.childNodes[i],
previous);
        previous = newspan.childNodes[i];
    }
}

function nevow_closeLive(evalAfterDone) {
    // Tell connect() not to complain at us when the server closes the
    // connection with no serverToClientEvent
    liveevil_unload = true
    var old_auto_open = auto_open
    auto_open = false
    // Tell the server we know we're done, send us an empty event
    // evalAfterDone will be evalled after the server sends us an empty
event
    nevow_clientToServerEvent('close', '', evalAfterDone)
    auto_open = old_auto_open
}

var server = {
    handle: function(handlerName) {
        var args = [handlerName, '']
        for (var i = 1; i < arguments.length; i++) {
            args.push(arguments[i])
        }
        nevow_clientToServerEvent.apply(this, args)
    }
}

[Twisted-web] livepage-notification branches

James Mayfield