Extended Object Model

The WTE uses the same component object model (COM) used by Microsoft Internet Explorer. In fact, the engine is essentially Internet Explorer without the graphical user interface (GUI). This means that all the Internet Explorer scripting objects available to regular Web sites are also available to Web telephony applications. Also, the WTE extends the Internet Explorer object model with additional objects that support Web telephony applications. The extensions are referred to as the Web telephony extended object model.

Applications have access to the extended object model through the ExOM object. The engine includes a predefined reference to the ExOM object called External, which applications can use to access the object directly. The External object provides access to the following objects:

• WTEApplication object — Lets an application query and change its own configuration parameters. An application accesses its configuration parameters by using the Configuration property on the External object. For more information, see Web Telephony Configuration Object.
• Session object — Lets an application store strings, numbers, and objects that it needs to use before answering a call, during the call, and after the call is disconnected. Variables stored by using the Session object are available to all pages for the duration of the session.
• Internet Explorer Event object — Lets an application access the WTE private event object, which is similar to the Event object of Internet Explorer. For more information, see Handling Events.
• TAPI Call object — Lets an application perform telephony operations through a telephony service provider such as a voice board or voice modem.
• TTSMode object — Lets an application query the read-only properties of the TTS engine.
• SRMode object — Lets an application query the read-only properties of the SR engine.
• LogCustomField object — Lets an application set the contents of the custom field in the Web telephony event log.

For more information, see Extended Object Model Overview.