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From: "Richard Maher" <maher_rj@hotspamnotmail.com>
Newsgroups: comp.lang.java.programmer,comp.lang.javascript
Subject: Java7 Applet Status and Event Handlers
Date: Thu, 26 Apr 2012 20:42:52 +0800
Organization: HTTP *is* The Box - Let's think outside
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Hi,

I found the following pages and find them very interesting and useful: -
http://docs.oracle.com/javase/7/docs/technotes/guides/jweb/applet/appletStatus.html
http://docs.oracle.com/javase/tutorial/deployment/applet/appletStatus.html
a good example of use: -
http://docs.oracle.com/javase/tutorial/deployment/applet/examples/dist/applet_StatusAndCallback/AppletPageUpdatedDuringLoading.html

The only thing  is, I'd really much rather stick to my old and very simple 
strategy of "app=document.getElementById(appletId); app.someMethod();" and 
block synchronously until the applet is loaded. The problem is that although 
that strategy works like a charm with FireFox, Opera, and Safari, it falls 
over on slow machines on the JVM initialization when using Chrome or IE :-(

So I'm thinking new Applet event handling in Java 7 would lead one to 
believe this is the way to go but, alternatively, if someone can show me a 
simple way to reintroduce the blocking behaviour with IE and Chrome I'd much 
appreciate it! Some want/require a "lazy load" but I do not!

Cheers Richard Maher

PS. Below is the existing code that I guess I'm going to have to introduce 
the JAVA_STATUS_EVENTS parameter to: -

/**
 *  Copyright (c) Richard Maher. All rights reserved.
 *
 */

function Tier3Client(application,
                     codeBase,
                     port,
                     maxBuf,
                     hostCharSet,
                     sslReqd)
{
    this.facPrefix   = "T3$";
    this.application = application;
    this.codeBase    = codeBase;
    this.port        = port;
    this.maxBuf      = maxBuf;
    this.hostCharSet = hostCharSet;
    this.sslReqd     = sslReqd;
    this.msgPend     = new Array();

    var appletId = "Tier3__" + application + "_Applet";

    try {
        var idTaken = document.getElementById(appletId);
    }
    catch (err) {};

    if (idTaken != null) {
        throw new Error("Tier3 Client already registered for " + 
this.application);
        return;
    }

    var archiveName = "tier3Client.jar";
    var className   = "tier3Client/Tier3Application";

    var appletParams = [{"name":"archive",     "value":archiveName},
                        {"name":"codebase",    "value":codeBase   },
                        {"name":"code",        "value":className  },
                        {"name":"mayscript",   "value":"true"     },
                        {"name":"scriptable",  "value":"true"     },
                        {"name":"APPLICATION", "value":application},
                        {"name":"PORT",        "value":port       },
                        {"name":"MAXBUF",      "value":maxBuf     },
                        {"name":"HOSTCHARSET", "value":hostCharSet},
                        {"name":"SSLREQD",     "value":sslReqd    }];
    var startParam = 0;

    var objectTag = "<object classid=";

    if (/Internet Explorer/.test(navigator.appName)) {
        objectTag = objectTag +
            '"clsid:8AD9C840-044E-11D1-B3E9-00805F499D93" ';
    } else {
        objectTag = objectTag +
            '"java:' + className + '.class" type="application/x-java-applet 
" ' +
            'archive="' + codeBase + archiveName + '"';
        startParam = 1;
    }

    objectTag = objectTag + ' width= "0" height= "0" id="' + appletId + 
'">';

    for (i=startParam; i<appletParams.length; i++){
        objectTag = objectTag + '<param name  ="' + appletParams[i].name  + 
'" ' +
                                       'value ="' + appletParams[i].value + 
'">';
    }

    objectTag = objectTag + "</object>";

    var appletDiv = document.createElement("div");
    appletDiv.innerHTML = objectTag;

    try {
        document.body.appendChild(appletDiv);
        this.chan = document.getElementById(appletId);
    }
    catch(err) {
        alert("Tier3 unable to load applet for " + this.application + 
": -\n" + err.description);
        this.chan = null;
    };

    if (this.chan == null) {
        throw new Error("Tier3 was unable to initialize the applet for " + 
this.application);
        return;
    } else {
        if (!this.chan.isAuthorized()) {
            throw new Error("Tier3 User authentication unsuccessful for " + 
this.application);
            return;
        }
    }

    Tier3Client.applications[this.application] = this;

    return this;
}

Tier3Client.MAJVERS = 1;
Tier3Client.MINVERS = 0;

Tier3Client.launder =
    function(jsobject) {
        return jsobject;
    };

Tier3Client.prototype = {

    send:
        function(msgBody, callback)
        {
            if (arguments.length < 2) {
                throw new Error("Insufficient arguments for send(msgBody, 
callback)");
            }

            var chan         = this.chan;
            var callbackArgs = new Array();
            var responseCnt  = 0;
            var i            = 0;

            var msgCandidate =
            {
                msgSlotId     : -1,
                msgSeqNum     : -1,
                chan          : chan,
                callback      : callback,
                callbackArgs  : callbackArgs,

                dispatcher    :
                    function(responseMsg,
                             msgSlotId,
                             msgSeqNum)
                    {
                       this.responseCnt++;
                       this.msgSlotId  = msgSlotId;
                       this.msgSeqNum  = msgSeqNum;
                       callbackArgs[0] = responseMsg;

                       try {
                           callback.apply(this, callbackArgs);
                       }
                       catch (err) {
                           throw new Error("Error calling callback 
routine: -\n" + err.description);
                       }
                    },

                getMsgSeqNum  :
                    function() {
                        return this.msgSeqNum;
                    },

                getResponseCnt:
                    function() {
                        return this.responseCnt;
                    },

                complete      :
                    function() {
                        return chan.complete(this.msgId);
                    }

            };

            if (typeof callback != "function") {
                throw new Error("The 'callback' parameter is not a 
function");
            }

            for (i=2; i<arguments.length; i++) {
                callbackArgs[i - 1] = arguments[i];
            }

            return chan.send(msgCandidate, msgBody);
        }

};

Tier3Client.applications = {};