INFO: FAQ on Developing with the Internet Client SDK (167435)

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Setup
Q. What are the system requirements for installing the SDK?

A. To download and use the Internet Client SDK, you will need the following:
- The Internet Explorer 4.0 or 4.01 (Internet Explorer 3.x and preview releases of Internet Explorer 4.0 are not supported.)
- Windows NT 4.0 or Windows 95. More recent beta versions of Windows were not targeted for support, but might work if you upgrade to Internet Explorer 4.0 Preview 2.
Active Desktop
Q. I can't seem to turn ActiveDesktop on from an NT Server box. Am I missing something?

A. Active Desktop is currently disabled by default on Windows NT Server machines. You can turn it on by removing the "NoActiveDesktop" restriction found under the following registry key and then rebooting the machine:
```
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\ 
      Policies\Explorer
						
```
Channels
Q. What MIME type do I specify in my dynamically generated CDF file? CDF files that are dynamically generated through Active Server Pages (ASP) should insert the following line at the top of the file (before any CDF lines):
```
<% Response.ContentType = "application/x-cdf" %>
						
```
This ensures that servers return the correct MIME/content type "application/x-cdf."

Problems with CDF files being displayed as HTML text inside the Internet Explorer 4.0 browser, instead of invoking the subscription wizard, may likely be caused by the server returning the incorrect MIME type of "text/html" instead of the desired "application/x-cdf".
Q. When dynamically generating a CDF file from an Active Server Pages (ASP) page, is the ASP file the one the user needs to subscribe to?

A. Yes, assuming that the correct CDF MIME type is specified in the ASP page, as illustrated in the FAQ above, double-clicking on a link to the ASP file should bring up the CDF subscription wizard appropriately.
Q. I cannot use the ampersand character in my CDF TITLE. Do I have to treat certain characters special when working with CDF files?

A. As mentioned in the "CDF Parsing Rules and Hints" section of the CDF Reference, CDF supports encoding of ASCII characters with the format &#nnn. The ampersand character, therefore, could be encoded with its ASCII decimal value of 38 by using the string &#038.

To specify "Peaches & Cream", for instance, here's what your <TITLE> tag would look like:
```
<TITLE>Peaches&amp;#038;Cream</TITLE>
						
```
Q. Is it necessary to specify the <!DOCTYPE> tag in my CDF file?

A. No, Internet Explorer 4.0 does not use the <!DOCTYPE> tag.
Q. Is http://www.w3.org/channel.dtd a valid URL for a <!DOCTYPE> tag?

A. No, this URL is only an example, does not actually exist, and is best not used in actual CDF files.
Q. Is there a way to detect from an HTML page whether the user is already subscribed to it?

A. Currently there is no way to do this, although the possibility of exposing this information from the HTML object model is currently being investigated.
Q. Is there a difference between the subscription cache and the regular cache that Internet Explorer maintains?

A. All subscription information go into the same cache maintained by Internet Explorer. The subscription content in the cache, however, is especially marked so that it does not get deleted when a user clears the cache.
Q. If the user is browsing a subscribed channel while they are connected to the Internet, is content pulled from the cache, or does Internet Explorer query the server again?

A. Internet Explorer looks at the expires HTTP header returned by the server when the page was retrieved and checks to see if the cached page is still valid. If it is, then content is pulled from the cache; otherwise, Internet Explorer queries the server again for the content. Note that with the latter, when Internet Explorer re-queries the server for content, in most cases, Internet Explorer will issue an HTTP GET request with an If-Modified-Since header, which helps reduce the server load.
Q. Does the actual download of the HTML page occur upon subscription to the site, or only during a subscription update?

A. Actual download occurs during subscription update. However, users can manually update a subscription any time they want.
Q. From a CDF file, is there a way to specify items to be cached, without having the items appear in the channel bar's item list? For example, can I specify a WAV file to be downloaded as part of the subscription update, so that it gets cached and is available when the user browses offline?

A. Yes, here's the correct way to do this:
```
<WWITEM HREF="http://example.microsoft.com/sound.wav">
   <USAGE VALUE="NONE"></USAGE>
</WWITEM>
						
```
Note that in XML, an element that does not have child elements can be represented in a more compact format. For instance, the above <USAGE> line could be written more compactly in this manner (note the final / at the end of the tag):
```
<USAGE VALUE="NONE"/>
						
```
Also, when listing multiple items that are to be cached but not viewed in the channel pane, instead of marking each one with a <USAGE VALUE="NONE"/>, it is better to place them all in one sub-channel that is marked with a usage tag, as illustrated in the example below:
```
<CHANNEL>
   <USAGE VALUE="NONE"/>
   <WWITEM HREF="http://example.microsoft.com/sound1.wav"/>
   <WWITEM HREF="http://example.microsoft.com/sound2.wav"/>
   <WWITEM HREF="http://example.microsoft.com/sound3.wav"/>
</CHANNEL>
						
```
Q. Is there a way to specify the order of items to be cached from a CDF file? We want to ensure that high priority items are downloaded first during a subscription update.

A. No, there are no plans to support for this for Internet Explorer 4.0.
Q. Is it possible to specify multiple schedules for updates in one CDF file?

A. No, only one schedule can be specified per CDF in Internet Explorer 4.0. Also, a desktop component cannot be bundled with a channel in one CDF. They have to be two separate CDFs to work correctly.
Q. Is it possible to specify a global time for the <SCHEDULE> tag, so that my channel updates occur between certain times, regardless of the time zone?

A. Currently there is no way to specify local or global time in a CDF file. Information specified in the <EARLIESTTIME> and <LATESTTIME> tags are both considered local and ignore any timezone information specified in the <STARTDATE> and <ENDDATE> tags.
Q. How do I keep Internet Explorer 4.0 from opening a new window when a user clicks on a link from a desktop component?

A. The way to do this is to specify a TARGET="_top" with the <A HREF> tag.
Q. I haven't been able to get my desktop component to work unless I put it on a separate CDF from the rest of my channel. Is this how it's designed to work?

A. Yes, desktop components have to be in a separate CDF file from the rest of the channel.
Q. I notice that a TDC contained in a Desktop component does not render data correctly. What am I doing wrong?

A. This is a known problem with no workaround available at the moment. We will post more information here as it becomes available.
Q. I notice that the text I specified in my <ABSTRACT> tag gets truncated when displayed as a tooltip from the Channel Bar. Is there a limit to the number of characters I can specify in my channel's <ABSTRACT> tag?

A. This is a bug in the current implementation of the Channel bar and should be fixed in a future build. Dynamic HTML
Q. Is there a way to implement a custom tooltip over anchors in Internet Explorer 4.0 (the same way you can use the ALT attribute in an <IMG> tag)?

A. By default, Internet Explorer 4.0 renders the URL of the HREF as a tooltip, which may not always be the desired behavior. Yes, the way to do this is to specify the tooltip in the TITLE attribute of the <A tag> as in this example:
```
<a href="file.htm" TITLE="Tooltip goes here">some text</a>
						
```
Q. How can I change the HTML or text associated with an element? I used to be able to do this using the rangeFromElement method, but now I keep getting the error "Object does not support this property or method." Have things changed?

A. Yes, the rangeFromElement method has been removed. Use innterHTML/outerHTML and innerText/outerText to manipulate text or HTML.
Q. Why do I get an "Object does not support this property or method" error when using the multimedia controls in my page?

A. Considerable changes have been made to the multimedia controls in Internet Explorer 4.0 Preview 2. For information on the multimedia controls, please refer to the Internet Client SDK documentation under the "Internet Multimedia" section. More documentation which highlights all the differences will be made available shortly.
Q. How do I determine the client width and height?

A. There are new properties on the body object, clientWidth and clientHeight, which can be used for this purpose.
Q. How do I change the current cursor being used as mouse pointer?

A. Yes, there is a cursor CSS attribute that can be used. Refer to the Internet Client SDK documentation under Dynamic HTML\HTML and CSS Reference section for more information.
Q. Why do I get the error "Wrong number of arguments" in my event handlers?

A. Events do not have parameters. All information can be retrieved using the window.event object.
Q. I'm finding that IFRAMES within a relatively positioned <DIV> tag causes Internet Explorer 4.0 to crash every time. This makes it difficult to relatively position IFRAMES. Is this a known problem, and is there a workaround?

A. Yes, this is a known problem. The workaround is to put the positioning on the <IFRAME> directly.
Q. Is there a list of known issues related to CSS positioning and repainting?

A. Here's a list of what should be working by Internet Explorer 4.0 Preview 2:
- Display Property
- Visibility Property
- Hit testing correctly
- Nested DIVs
- Accurate Positioning
- Overflow property
Here is a list of what may not work properly by Internet Explorer 4.0 Preview 2:
- Clip property
- Positioned items with unspecified width/height; (that is, all positioned items must have a width and height -- this can be in percentage)
- Width=auto
- Negative z-index
- Selection
WebBrowser Control
Q. In the WebBrowser documentation for Visual Basic developers, the Navigate and Navigate2 methods look identical. Is there a difference?

A. The only difference is that the URL parameter is packaged as a VARIANT in Navigate2 instead of a BSTR. (You could verify this in the WebBrowser documentation for C/C++ developers.) Unlike a C++ application, a Visual Basic application is not able to use the WebBrowser control to navigate into special folders in the shell namespace like "My Computer." Currently, the shell does not expose an object that provides a PIDL, which a VB application can then use in a Navigate2 call.

For additional information about WebBrowser navigation using a PIDL from a C++ application, please see the following article in the Microsoft Knowledge Base:
167834 HOWTO: Web Browser Navigation Using a PIDL
Q. I have an application that uses the WebBrowser control. Is it possible to install just the WebBrowser control, without installing Internet Explorer 4.0?

A. No, there is no way to do this for both Internet Explorer 3.x and Internet Explorer 4.0. The minimal install will install the browser. Also, note that Internet Explorer 3.x and 4.0 cannot coexist on the same machine. Please see the following Web page for more information about redistributing Internet Explorer:
http://www.microsoft.com/ie/ieak/
Component Packaging
Q. When downloading a digitally signed file, rather than popping up the Certificate dialog box as expected, a message box comes up indicating that the file has been digitally signed but that it cannot be confirmed. What's wrong?

A. Microsoft has recently confirmed a rare Certificate Verification bug caused by the REG files offered as part of the tools set of the ActiveX SDK. The bug is that the REG files, Wvtston.reg and Wvtstoff.reg, sets the system to check Verisign's revocation server extraneously. This error occurs only when your system is set to check the Revocation server, and the Revocation server itself is down (a very rare occurrence).

The recommended solution is to use SetReg.exe available in the Internet Client SDK's \Inetsdk\Bin folder, rather than the REG files in the ActiveX SDK. SetReg.exe should be used to disable Revocation checking on your machine.

By issuing the following command, the off-line revocation server for individual certificates is disabled:
```
setreg 4 true
						
```
By issuing the following command, the off-line revocation server for commercial certificates is disabled:
```
setreg 5 true
						
```
Q. What version of the MFC DLLs will ship with Internet Explorer 4.0? I'd like to know so I don't have to worry about packaging the MFC DLLs with my ActiveX Control.

A. Any component should be careful not to rely on the presence of any MFC DLLs with the currently installed browser, as Internet Explorer 4.0 and future versions of Internet Explorer may ship alternative versions, or may not even ship any MFC DLLs at all.

A component that uses the MFC DLLs as dependencies should package the MFC DLLs accordingly. For additional information about how to correctly package MFC DLLs correctly with your MFC component, please see the following article(s) in the Microsoft Knowledge Base:
167158 HOWTO: Packaging MFC Controls for Use Over the Internet
Q. Is there a way to see a debug trace of code download activity in Internet Explorer 4.0?

A. In Internet Explorer 3.x, this was made possible by installing the debug versions of Urlmon.dll and Wininet.dll. In Internet Explorer 4.0 Preview 2, there is a tool available in the Internet Client SDK that allows you to do this more easily. Check out \Inetsdk\Bin\Cdllogvw.exe. There is also a Cdllogvw.txt available in the same directory for more details.
Q. I've written an ActiveX control that I've marked as Safe for Scripting and I'm having trouble getting it to work when running off a page on a local hard drive. What am I doing wrong?

A. The problem may be due to any of the following:
- A missing dependent DLL.
- Necessary security level set on the wrong zone.
- A control that is not marked as "safe for scripting and initialization" will not be loaded if the page that references the control is being accessed from the local hard drive. Note that this behavior may or may not change in future builds of Internet Explorer.
For more information on marking ActiveX controls as "safe for scripting and initialization", please refer to the Internet Client SDK docs on "Safe Initialization and Scripting for ActiveX Controls" under the Component Development/ActiveX Controls section. Control Development
Q. How can I improve performance in my ActiveX Control?

A. For better performance make your control an apartment model control. Internet Explorer 4.0 uses multiple threads and may host the control in a secondary thread. If the control is not created as apartment model aware and marked as such, it is created and executed in the context of the calling application's primary thread, requiring calls on the control's methods to be marshaled between threads. This can cause a performance hit and can be very prominent if there are many non- apartment model controls in an HTML page. To make a control apartment model, the control needs to be marked as such in the registry and has to be written so that it is apartment model safe.

More information on apartment model and other threading models can be found in the following article in the Microsoft Knowledge Base:
150777 INFO: Descriptions and Workings of OLE Threading Models
Q. What is the secret to debugging a control embedded in an HTML page in Internet Explorer 4.0? Whenever I try to start a debug session with Internet Explorer 4.0 in the Visual C++ debugger, I get kicked out of the debugger.

A. With Internet Explorer 4.0's shell integration, this is not as straightforward as debugging controls in Internet Explorer 3.x. The details on how to do this correctly are outlined in the following article in the Microsoft Knowledge Base:
167715 HOWTO: Debugging ActiveX Controls in IE 4.0 Browser
Scripting
Q. How do I determine from a script if the Internet Explorer 4.0 browser is running off-line or not?

A. Currently, there is no way to determine this from a script.

Although the IWebBrowser2 interface provides a get/put_Offline method that indicates whether or not the WebBrowser is reading from the cache, there is no way to get this information from the WebBrowser object model up to the script level. If desired, you could write an ActiveX control that gets this information from the WebBrowser object model and expose it as a property or method, which can then be accessed from a script.

We are currently investigating the possibility of exposing this in the Dynamic HTML Object Model, so as to be accessible from JAVA applets as well.
Q. Why do I get a Permission Denied error whenever I try to access a frame's document from a script written in another frame's document? The same code runs fine in Internet Explorer 3.x.

A. This is due to a cross-frame security feature that's implemented in Internet Explorer 4.0, but not in Internet Explorer 3.x. A frame running on one server is not able to access another frame's document running on another server. Similarly, with the introduction of zones in Internet Explorer 4.0 Preview 2, a script cannot access pages across zones.

For additional information about this new cross-frame security in Internet Explorer 4.0, please see the following article(s) in the Microsoft Knowledge Base:
167796 PRB: "Permission Denied" When Scripting Across Frames
Q. Why do I get a Permission Denied error whenever I try to access a frame on a different first tier domain, but on the same second tier domain?

A. This is another side effect of Internet Explorer 4.0's cross-frame security feature described above. A frame running on example1.microsoft.com cannot access a frame on example2.microsoft.com.

The correct way to do this is to set the domain property on both pages to the common substring domain. In this case, setting the domain to microsoft.com, as illustrated below:
```
<SCRIPT>
   document.domain = "microsoft.com"
</SCRIPT>
						
```
Q. From a client-side script, how do I check for the browser version so my application can degrade gracefully if the browser does not support the new Internet Explorer 4.0 features?

A. You can use the JScript function below to determine the version of the browser it is running on from a client-side script. The function returns the major version number for any Microsoft Internet Explorer browser, and zero (0) for others. Use of this function assures that the script is compatible with future versions of the Internet Explorer.
```
// This function returns Internet Explorer's major version number,
// or 0 for others. It works by finding the "MSIE " string and
// extracting the version number following the space, up to the
// decimal point, ignoring the minor version number

<SCRIPT LANGUAGE="JavaSCRIPT">
function msieversion()
{
   var ua = window.navigator.userAgent
   var msie = ua.indexOf ( "MSIE " )

   if ( msie > 0 )      // If IE, return version number
     return parseInt (ua.substring (msie+5, ua.indexOf (".", msie )))
   else                 // If another browser, return 0
      return 0
}
</SCRIPT>
						
```
For additional information, please see the following article(s) in the Microsoft Knowledge Base:
167820 HOWTO: Determining Browser Version from a Script
Q. Is there a way to detect the browser's support for the new Internet Explorer 4.0 features from a server-side script?

A. The Browser Capability component that comes with Active Server Pages (ASP) provides your scripts with a description of the capabilities of the clients Web browser by comparing the User-Agent HTTP Header with the entries in the Browscap.ini file. In order for an ASP application to detect the browser's support for the new Internet Explorer 4.0 features, copy the latest Browscap.ini from http://www.cyscape.com/browscap/ to your \windows\system32\inetsrv\asp\cmpnts directory and execute a server-side script similar to the example described in following article in the Microsoft Knowledge Base:
167820 HOWTO: Determining Browser Version from a Script
HTML
Q. Why are my HTML pages with frames not showing up in Internet Explorer 4.0? They used to work fine in Internet Explorer 3.x.

A. Unlike Internet Explorer 3.0, Internet Explorer 4.0 does not support <FRAMESET> tags embedded within <BODY> tags. This was done in Internet Explorer 4.0 to ensure compatibility with Netscape. To work around the problem, move the <FRAMESET> outside the <BODY> tags.

In some cases, a <NOFRAMES> element is specified within the <FRAMESET> tags, as in the example below:
```
<BODY>
  <FRAMESET>
   <NOFRAMES>Sorry, your browser does not support frames! </NOFRAMES>
  </FRAMESET>
</BODY>
						
```
Although Internet Explorer 4.0 supports frames, when the above HTML code is displayed in Internet Explorer 4.0, the content specified within the <NOFRAMES> tag is displayed. Moving the <FRAMESET> outside the <BODY> tags causes the page to display correctly.
Q. Why doesn't Internet Explorer 4.0 close the <PLAINTEXT> container like Internet Explorer 3.x did?

A. The <PLAINTEXT> tag is designed to render all of a Web page's subsequent text without parsing any tags, including its own </PLAINTEXT> tag. Internet Explorer 4.0 supports this tag as it is defined by the HTML DTD. This element is not recommended as different browsers may not support it consistently. Instead, use the <PRE> tag and display all reserved characters (such as brackets) with their corresponding HTML character entities. Miscellaneous
Q. I notice that my remote calls are failing on Internet Explorer 4.0, although when I install the DCOM95 Web release, everything suddenly works correctly. What's wrong?

A. Pre-Beta1 Internet Explorer 4.0 setup failed to properly create the "DCOM Protocols" value under the registry key HKLM\Software\Microsoft\RPC. Although Internet Explorer 4.0 setup writes a value in the registry, it is an sz value rather than the required multisz. If Internet Explorer 4.0 were installed on a system that previously had DCOM95 installed, you would not see the problem.

This problem is fixed in the Beta1 release of Internet Explorer 4.0.
Q. Is it possible to have Internet Explorer 3.x and Internet Explorer 4.0 coexist on the same machine?

A. No, there are no plans to support the coexistence of these two Internet Explorer versions at this time. Internet Explorer 3.x and Internet Explorer 4.0 share system components that cannot exist in multiple copies on the same machine.
Q. What is the difference between ADO and ADOR, and which should I be using on my Web pages?

A. The Active Data Object (ADO) components ship in two forms - one for a Web server, and another for the client. The ADO component installed with Internet Explorer 4.0 is the ADO Recordset (ADOR). ADOR provides an object model for script access to data supplied by a data source object (DSO) embedded in a Web page. It does not, however, provide ADO Connection or Command objects. These are provided only as part of the server installation.

Included with the Internet Client SDK in self-extracting archives is the full set of ADO components. When building applications using ADO for Internet Explorer 4.0, your client side scripts should depend only on the availability of the Recordset object. The full ADO interfaces are intended for use with Active Server Pages and custom business objects that run on a Web server. Refer to Mdac.txt in the Inetsdk\Bin folder for more details.

The third-party products that are discussed in this article are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, regarding the performance or reliability of these products.

INFO: FAQ on Developing with the Internet Client SDK (167435)

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