How to use TLB file to access methods in a scripting client

**pradish** · July 22nd, 2009, 04:01 AM

Hi all

i have an IDL file, from whcih i can get the TLB file, now using this TLB, can i have an scripting client buit using java/vb script acces all the com methods and even suport the callback

i dont have the COM Dll for the IDL, we have app which only give the IDL.

regards
pradish

**cilu** · July 22nd, 2009, 07:27 AM

The code resides in the DLL. What would you be calling if you don't have the DLL?

**pradish** · July 22nd, 2009, 09:44 AM

yeah.you are right. the queston was not framed properly
i have dll, but it is not COM dll, i thought tlb is enough for the
scripting clients and can make call in to the regular dll, but i
guess it will not work.

so i am writing a COM wrapper ove this regulat dll, then how
do i call a COM method , which returns a interface pointer and
that interface pointer is not derived from IDispatch.

Thank you cilu for the correction

regards
pradish

**Arjay** · July 23rd, 2009, 02:12 AM

A good book to learn about this is Beginning ATL 3 COM Programming.

**CBasicNet** · July 23rd, 2009, 04:12 AM

Originally Posted by pradish

yeah.you are right. the queston was not framed properly
i have dll, but it is not COM dll, i thought tlb is enough for the
scripting clients and can make call in to the regular dll, but i
guess it will not work.

so i am writing a COM wrapper ove this regulat dll, then how
do i call a COM method , which returns a interface pointer and
that interface pointer is not derived from IDispatch.

Thank you cilu for the correction

regards
pradish

The COM interface pointer have to be derived from IDispatch, else you cannot call your methods in Javascript and VBscript.

**pradish** · July 23rd, 2009, 08:20 AM

Thank you all for the replies...

i am able to call a interface method, but how do i implement a callback
supposing my components supports the connection point and calls

Fire_OnNewEvent();

what code should i write in javascript on a HTML page to catch this event

regards
pradish

**Arjay** · July 23rd, 2009, 11:35 AM

Search google for "COM JavaScript connection points" and look at the first 3 hits.

**pradish** · July 24th, 2009, 01:37 AM

i have already done that, all the three are quires or problems they face while implementing callbaks , with one very compicated example in code project.

this is my HTML code , wherein the interface method call is working , but the callback nerver gets called

<html>
<head>
<title>My Com Component</title>

<OBJECT ID="MyObj" CLASSID="CLSID:5F19E5E7-4617-4D24-A30D-F4D5C2605E66">

</OBJECT>

<script language="javascript" type="text/javascript">

function InvokeComMethod()
{
alert("The InvokeComMethod ");
var returnCode = MyObj.AddAndFill(10,90);
alert("The Sum of Two numbers is = "+returnCode);
}

function MyComComponent_onload()
{
InvokeComMethod();
}

function MyComComponent_onunload()
{
MyObj.Dispose();
}

</script>
//The callback code , TakeIT is a callback function (i used the
//connection point wizard to generate the code and Fire_TakeIT() is also
//succesfull, but this code never gets called
<script language="javascript" type="text/javascript">
MyObj.attachEvent('TakeIT', onActionDone);
function onActionDone()
{
alert("!")
}

</script>

</head>
<body onload="MyComComponent_onload();" onunload="MyComComponent_onunload();">
<h1>My Com Component</h1>

</body>
</html>

**Arjay** · July 24th, 2009, 08:46 AM

What happens when you step through the code in a debugger?

Open the COM dll project in Visual Studio and point the startup exe to IE and pass in the test web page as a startup parameter. Then set breakpoints on the on load function, create connection point, and so on to see if your break points get hit.

The end goal here is to determine where the issue is. It is the scripting code or inside the COM server? Btw, how do you write the COM dll? Did you use ATL?

**pradish** · July 24th, 2009, 09:34 AM

Hi all,

Thankyou for all the inputs.

The problem here was that for IE as a client to support the callback , the CoClass should implement IProvideClassInfo2Impl more in this KB

http://support.microsoft.com/kb/200839

after doing the changes , it worked fine.

regards
pradish

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