NetMeeting 3.0 Resource Kit

This chapter describes the Microsoft® Windows® NetMeeting® 3 architecture so that you can better understand how the key elements function and interrelate. Each of the NetMeeting standards-based components is described in more detail in the following chapters:

• Chapter 3, "Finding People," which describes the Lightweight Directory Access Protocol (LDAP) standard for directory services support 

• Chapter 10, "Understanding the T.120 Standard," which describes the T.120 standard for data conferencing 

• Chapter 11, "Understanding the H.323 Standard," which describes the H.323 standard for audio and video conferencing 

• Chapter 12, "Conferencing Standards," which describes the organizations that develop and ratify industry standards 

NetMeeting functions as both a client and a platform. The NetMeeting client provides users the benefits of real-time audio, video, and multipoint data conferencing. The NetMeeting platform also provides software application programming interface (API) support so that software developers can integrate these conferencing features into their own products and services.

To support this dual purpose, NetMeeting capabilities are built on an architecture of interworking components. Each component communicates with and passes data to and from the component layer above and below. This architecture, which is based on industry standards, ensures that manufacturers can easily develop products and services that build on the NetMeeting platform and interoperate with NetMeeting client conferencing features.

At the core of the NetMeeting architecture is a series of data, audio, and video conferencing and directory service standards. The following illustration shows how these standards work together with transport, application, user interface, and the Windows NetMeeting 3 Software Development Kit (SDK) components to form the NetMeeting architecture.

At its lowest level, standards are responsible for translating, sending, and receiving NetMeeting information. The NetMeeting architecture includes protocols for network Transmission Control Protocol/Internet Protocol (TCP/IP) connections.

Information can be transported over the Internet or corporate intranet using TCP and User Datagram Protocol (UDP) connections. TCP is used primarily for data transport and call control, while UDP represents secondary connections for sending and receiving NetMeeting audio and video. Winsock provides the interface to the network stack, and maps information between the programs and the network. The following illustration shows this transport layer.

By supporting the following industry standards, NetMeeting can interoperate with standards-based products from other companies:

• T.120 

  The International Telecommunications Union (ITU) T.120 standard for data conferencing includes the T.126 Whiteboard, T.127 file transfer, and T.128 program sharing standards. This standard provides the protocols for establishing and managing NetMeeting data flow, connections, and conferences. T.120 also includes T.123 Annex B security capabilities for secure call negotiation and data encryption. 

• H.323 

  The ITU H.323 standard for audio and video conferencing provides a set of standard audio and video codecs for encoding and decoding the input and output from audio and video sources that is transmitted over various connection rates. By using these H.323 audio and video codecs, NetMeeting can support many different modes of Internet telephony and can send and receive audio and video information to H.323-compatible nodes. The H.323 standard also includes framing, call signaling, and call control protocols for negotiating the information flow and sequencing.

• LDAP 

  The Internet Engineering Task Force (IETF) LDAP standard provides the directory services support for NetMeeting. The Microsoft Internet Locator Service (ILS) servers utilize the LDAP interface to create directories of current NetMeeting users that people can call and communicate with over TCP/IP connections.

These standards provide the framework for managing NetMeeting connections, data conferencing, audio and video capabilities, and directory server access. The following illustration shows these features.

The NetMeeting user interface (UI) provides an easy-to-use format with icons and buttons. This UI is flexible, allowing users to view the full NetMeeting window, or a compact window that shows either the data conferencing features only or the audio and video conferencing features only. The following illustration shows this part of the architecture.

The NetMeeting SDK provides software developers with software application programming interface (API) support and information to build solutions using the NetMeeting platform. They can incorporate NetMeeting features, such as program sharing, Chat, and Whiteboard, into their programs and Web pages.

The NetMeeting SDK includes the following components:

• An ActiveX® control for embedding the NetMeeting UI in Web pages by using JavaScript-compatible languages or Visual Basic® Scripting Edition, Visual Basic programs, and other OLE-enabled documents and programs. 

• A set of Component Object Model (COM) objects for supporting LDAP-based directories, called ILS servers, in your program. 

• A set of COM objects for installing custom audio and video codecs that NetMeeting can use during calls. 

For more information about the Microsoft Windows NetMeeting 3 Software Development Kit, visit the NetMeeting Web site: https://www.microsoft.com/netmeeting/sdk/ 

For more information about using the ActiveX control component of the SDK to embed conferencing features in Web pages, see Chapter 6, "Using NetMeeting on Web Pages."