[Info-vax] Useful Javascript example

[Richard Maher]

Hi,

Just following on from my response to John Cookson's Future of Programming
thread let me expand on my reference to the Tier3Client object class.
Basically, it creates the Applet's <object> tag for you on-the-fly, and has
the benefit of permitting the run-time discovery and inclusion of
Tier3Client functionality. Appended below is the complete definition (225
lines) but the parameters are as follows: -

application = The name of you've chosen for your Tier3 application
codeBase = The URL for locating the tier3Client.jar file (This must also be
the VMS server that is hosting your Tier3 Application Servers and that you
will be connecting back to)
port = The TCP/IP port number that your application is listening on
maxBuf = The maximum size of a single message in bytes
hostCharSet = The character set for encoding socket traffic
sslReqd = Do you need SSL on the socket (Requires STUNNEL on the server)
guiToolkit = GUI Toolkit for the Login dialog boxes. Currently only
Tier3Client.GUIAWT is available.
idleTimeout = Number of seconds to elapse before connection is closed due to
inactivity (0/null  is infinite)
verbosity = Minimum level of messages to log to the JAVA Console

Anyway I'm guessing/hoping it might come in useful some time not too far
away. . .

Cheers Richard Maher

PS. If you find any circular references then please let me know :-)

/**
 * Copyright (c) Richard Maher. All rights reserved.
 *
 * Tier3Client class bridges Javascript and Applet
 * functionality.
 */

function Tier3Client(application,
                     codeBase,
                     port,
                     maxBuf,
                     hostCharSet,
                     sslReqd,
                     guiToolkit,
                     idleTimeout,
                     verbosity)
{
    if (arguments.length < 4) {
        throw new Error("Insufficient arguments for Tier3Client");
    }

    if (!navigator.javaEnabled()) {
        alert("You must enable Java Applets in your browser\n" +
              "before you can successfully access this page");
        throw new Error("Java Applets are not enabled for browser");
    }

    this.application = application;
    this.codeBase    = codeBase;
    this.port        = port;
    this.maxBuf      = maxBuf;

    this.hostCharSet = (hostCharSet == undefined) ? "ISO-8859-1"        :
hostCharSet;
    this.sslReqd     = (sslReqd     == undefined) ? "N"                 :
sslReqd;
    this.guiToolkit  = (guiToolkit  == undefined) ? Tier3Client.GUIAWT  :
guiToolkit;
    this.idleTimeout = (idleTimeout == undefined) ? 0                   :
idleTimeout;
    this.verbosity   = (verbosity   == undefined) ? Tier3Client.WARNING :
verbosity;

    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":"java_version",
":"1.6+"          },
                        {"name":"mayscript",
lue":"true"          },
                        {"name":"scriptable",
ue":"true"          },
                        {"name":"codebase_lookup",
"false"         },
                        {"name":"APPLICATION",
"value":application     },
                        {"name":"PORT",
"value":port            },
                        {"name":"MAXBUF",
"value":maxBuf          },
                        {"name":"HOSTCHARSET",
"value":this.hostCharSet},
                        {"name":"SSLREQD",
     "value":this.sslReqd    },
                        {"name":"GUITOOLKIT",
     "value":this.guiToolkit },
                        {"name":"IDLETIMEOUT",
"value":this.idleTimeout},
                        {"name":"VERBOSITY",
     "value":this.verbosity  }];
    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);
    } else {
        try {
            if (!this.chan.isAuthorized()) {
                throw new Error("Tier3 User Authentication unsuccessful for
" + this.application);
            }
        }
        catch(err) {
            this.chan.setAttribute("id",null);
            this.chan = null;
            throw new Error("Tier3 unable to load applet for " +
this.application + ": -\n" + err.description);
        }
    }

    Tier3Client.applications[this.application] = this;

    return this;
}

Tier3Client.FACPREFIX = "T3$";
Tier3Client.MAJVERS   = 1;
Tier3Client.MINVERS   = 0;
Tier3Client.GUIAWT    = 1;
Tier3Client.DEBUG     = 0;
Tier3Client.INFO      = 1;
Tier3Client.WARNING   = 2;
Tier3Client.ERROR     = 3;
Tier3Client.FATAL     = 4;

Tier3Client.errorPage  = "Tier3Error.html";
Tier3Client.logoffPage = "Tier3Logoff.html";

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

Tier3Client.prototype = {

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

            if (typeof callback != "function") {
                throw new Error("The 'callback' parameter must be a
function");
            }

            var noWait = true;
            if (arguments.length > 2) {
                if (typeof async != "boolean") {
                    throw new Error("The 'async' parameter must be a
boolean");
                }
                noWait = async;
            }

            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;
                    },

                rendezvous    :
                    function() {
                        return chan.rendezvous();
                    }

            };

            for (i=3; i<arguments.length; i++) {
                callbackArgs[i - 2] = arguments[i];
            }

            return chan.send(msgCandidate, msgBody, noWait);
        },

    appendConsoleMsg:
        function(msg)
        {
            this.chan.appendConsoleMsg(msg);
        }
};

Tier3Client.applications = {};