Common problems with using ActiveX controls to develop Web pages

Source: Internet
Author: User
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1. What is an ActiveX control?

The microsoft®activex™ control is a reusable software component developed by software vendors. With ActiveX controls, you can quickly add special features to URLs, desktop applications, and development tools. For example, a StockTicker control can be used to instantly add activity information to a Web page, and animation controls may be useful for adding animation attributes to a Web page.

There are now more than 1000 commercial ActiveX controls that can be developed using a variety of programming languages, such as c,c++, the next generation of Microsoft Visual basic®, and Microsoft Visual Java Development Environment (Microsoft j+) +™. Once the ActiveX control has been developed, the design and developers can use it as a preinstalled component for developing client programs. Using ActiveX controls in this way eliminates the need for consumers to know how these components are developed and, in many cases, do not even have to program themselves to complete the design of a Web page or application.

Internet Explorer 3.0 is the first web browser to support ActiveX controls in Web pages. ActiveX controls can also be displayed in mosaic and Netscape Navigator using ActiveX plug-in for Netscape (see URL

2. Can Netscape navigator display ActiveX controls?

You can use ActiveX plug-in for Netscape to display ActiveX controls in Netscape Navigator. In the NCompass Lab Web site get the beta version of the plug-in. Internet Explorer 3.0 and Mosaicweb browsers can also display ActiveX controls.

3. What tools now support the use of ActiveX controls to develop Web pages?

Using Activexcontrolpad (see,, developers can easily insert ActiveX controls in HTML Web pages. Following the ActiveX Control Pad tutorial on the Web site, developers can easily learn to use ActiveX Controlpad. The SoftQuad company's HoTMetaL Pro also supports the use of ActiveX controls on HTML Web pages. In the coming months, Microsoft and its Third-party software vendors will also launch many web-making tools that support the use of ActiveX controls for Web-making.

4. Can only programmers use ActiveX controls?

Understanding scripting languages, such as Visual Basic scripting Edition (VBScript) or JavaScript™, is naturally useful for using ActiveX controls. However, it is not necessary to have such a process development base. For some controls, a certain number of scripts need to be written to be integrated into the Web page, but most ActiveX controls do not need this. With ActiveX control Pad, even non-program developers can insert many controls into a Web page by simply selecting and clicking on them.

5. After creating a Web page that contains ActiveX controls, how are the controls installed and displayed on the user's terminal if the user browses the page on his or her own machine?

When Internet Explorer 3.0 encounters a Web page that contains an ActiveX control (or composite control), first check the user's local system registration to see if the component is already installed on the local machine. If the component is already on the local machine, Internet Explorer 3.0 displays the Web page and activates the control. If the control is not yet installed on the user's local machine, Internet Explorer 3.0 automatically finds the control from the web and installs it on the local computer based on the address definition of the developer when the page is created.

6. How can you define an address on a Web page so that when users visit a Web page, the control is automatically downloaded to the user's computer?

Web developers can provide this information by setting the CODEBASE property to the control. When using ActiveX control Pad, in Objecteditor, you can see a property sheet that developers can easily use to set properties. By setting properties, you can define a URL address or set of addresses from which you can find and download controls on the Internet. It is the Internet Explorer3.0 that uses these address information to locate controls and automatically download components. After downloading, the Web page appears on the local machine. On the July 1996 Microsoft Systems Journal, the "Safe Web surfing with the Internet Component Download Service" is a detailed description of the entire information positioning and downloading process. It is necessary to mention that many of the controls provided by Microsoft (for example, HTML Layout control) do not require codebase settings because the ActiveX Object index can be based on the CLSID ( Control, locate and locate the control automatically.

7. Do you notify the user when the component is downloaded?

Yes. When a component needs to be downloaded, Internet Explorer 3.0 displays a message box by default informing the user that the download will begin. Users can choose to terminate the download or continue downloading. If the control is digitally signed, it provides a digital certificate, including the name of the software vendor that provided the control, and information about confirming that the control was not compromised. Software developers can digitally sign a control when they develop it. Signature information is carried by the control itself, so a digital validation book is automatically displayed before downloading, and users who use the control on the Web page do not need to do any development work.

8. Where do I put the control after downloading it?

By default, controls are downloaded to the ActiveX control cache in the \windows\occache directory.

9. How do I treat newly created new version controls? If you already have a boss's control on a user's computer how does Internet Explorer know that a new version of the control should be downloaded?

The Component Download service (Component Download service) in Internet Explorer 3.0 provides versioning functionality that allows new versions of controls to be automatically detected and downloaded automatically. In the July 1996 Microsoft Systems Journal magazine, the "Safe Web surfing with the Internet Component Download Service" is a detailed description of the entire version control process.

Does the 10.ActiveX control have a license issue? can users use ActiveX controls on their own web pages after downloading the controls?

ActiveX controls provide a complete set of safeguards to prevent unauthorized users from using ActiveX controls on a Web page. So far, there are a number of development tools that support this set of mechanisms, such as visual Basic, Microsoft Access, and Internet Explorer 3.0 Beta2 editions. The existing control licensing mechanism has two forms of licensing: development licenses and running usage licenses. The development license allows the holder of the license to use the control, use Visualbasic,activex Controlpad, and other relevant development tools to engage in development-related activities. Running a use license allows only the holder of a license to display controls in an existing application or Web page, and does not allow the control to be inserted into the tool for development purposes activities. The support license mechanism is the work of independent control development. Some control developers have chosen a development strategy that does not support license mechanisms, so for any user, the controls they develop can be used for development once they are installed on the local machine. Other control developers only provide free running licenses, and they need to charge for development licenses. Users who need to use controls on the Web should read the license agreement provided by the control developer in detail to determine their own permissions to use the control.

11. Why are some controls, even those with some visual Basic 4.0 self-contained controls, that cannot be displayed on Web pages with Internet Explorer 3.0?

Many controls, including some of the controls in VisualBasic4.0, provide a licensing mechanism. To use these controls on the Web, you must obtain a running usage license and place the appropriate license file on the Web page, otherwise you will not be able to display the control on the user terminal. For a control, only the legitimate developer of the control has the right to "run permission" for the control. For a detailed procedure to obtain permission to run a control in a Web page, see the License Control section in the ActiveX SDK documentation (for a specific example in the new ActiveX Controls Pad FAQ). It is worth mentioning that Microsoft and its Third-party partners have also provided a large number of ActiveX controls on the Web with free license to use. When you use these controls in a Web page, you do not need to submit a license file for use.

What controls does 12.Microsoft now provide? What controls are in ActiveX control pad and Internet Explorer 3.0?

On the Microsoft Web site, an ActiveX component Gallery (ActiveX Component Gallery) is provided, which gives A detailed list of currently available controls. Table 1 lists the controls in Internet Explorer 3.0 that can be installed from the MSDN Library.
It is worth mentioning that Microsoft and third party partners are constantly developing new controls. Many of these controls have been placed in Microsoft's ActiveX component library URL

13. Where can I get these ActiveX controls?

The Microsoft ActiveX component Library (ActiveX Component Gallery) has information about one and related connections that point to various ActiveX controls provided by Microsoft and third party developers.

14. Do third party software vendors now provide those ActiveX controls?

There are more than 1000 commercial controls currently provided by third party software developers. In the Microsoft ActiveX component Library (ActiveX Component Gallery), you can find a list of companies that develop Internet-enhanced ActiveX controls.

15. How can I develop a Web page that uses these ActiveX controls once the ActiveX controls are installed?

Use the ActiveX control Pad to insert these controls into the user's HTML Web page. Follow the ActiveX Controlpad online tutorials ( to learn how to use these tools ( See also Activexcontrolpad in http://www.'s Web page).

How does the 16.HTML Layout control enhance the ability to use ActiveX controls to develop Web pages?

The HTML layout control supports extended HTML published by the Web-site, allowing for precise positioning of objects on a page. Originally, HTML does not allow Web developers to use x, Y coordinates to precisely locate elements on a Web page, nor does it allow you to overlay objects. The newly added "2-d" layout feature enables developers to complete more complex designs, providing support for users to develop better Web applications. The HTML Layout control provides more advanced layout options for ActiveX controls that are displayed in Internet Explorer 3.0 by implementing the new HTML expansion of the consortium. The HTML layout control is a new component of Internet Explorer 3.0 and is integrated into the Internet Explorer 3.0 Full installation edition. (The HTML layout control is also part of the ActiveX Controlpad and can be installed through the MSDN Library.) ActiveX Control pad can be used in conjunction with HTML Layout control because it provides a full frame editor based on WYSIWYG pages. This makes it easier to develop advanced two-dimensional-style HTML designs with ActiveX controls.

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