Microsoft DirectPlay 8.0 Feature Overview

Microsoft® DirectPlay® is a media-independent networking API that provides networking services at the transport protocol and session protocol levels. DirectPlay's media independence means that DirectPlay sessions can be run on TCP/IP networks, IPX networks, and over directly connected modems and serial cables. DirectPlay's media independence also allows it to be extended in the future to support new standards and protocols as they become widely deployed, such as IPv6, multicast, or Quality of Service protocols. This means that DirectPlay applications can improve over time, and track evolving network standards, without additional development by the application developer. A list of transport and session level protocol services provided by DirectPlay is included below.

Additionally, in Microsoft® DirectX® version 8.0, DirectPlay has been written with massive scalability of servers in mind. It uses an asynchronous callback model that allows maximum parallelism, and takes advantage of Microsoft® Windows® 2000 performance features such as I/O completion ports. In version 8.0, DirectPlay is designed to scale up to the most ambitious massively multiplayer projects.

Also included in DirectPlay are the DirectPlay Lobby APIs, which allow applications to register themselves with DirectPlay so that other applications can easily launch them and pass them network addressing information. This allows you to write games that can be immediately launched by a number of different matchmaking services and utilities, without having to write special code for each launcher.

The DirectPlay Voice API is also included, which provides developers with everything they need to add real time voice communication to their applications with a minimum of development work, while retaining maximum flexibility. DirectPlay Voice includes extremely low bandwidth codec technology that can be used royalty free in your applications, as well as many features that allow you very fine grained control over the voice communication experience. A more detailed list of DirectPlay Voice features is included below.

DirectPlay provides the following services:

• Client/Server and Peer to Peer networking sessions
• Peer to Peer host migration
• Player and Group management
• Guaranteed and non-Guaranteed messaging
• Sequenced and non-Sequenced messaging
• Message fragmentation and reassembly
• Traffic throttling / Send queue monitoring
• Message priorities
• Connection statistics (round trip latency, packet loss, etc)
• Session description queries

DirectPlay Voice provides the following services:

• A selection of voice codecs from 64 kbit/sec down to 1.2 kbit/sec.
• Peer to peer, forwarding server, and mixing server topologies
• Completely flexible control of who hears whom within a session
• Automatic voice detection to control network transmission
• Automatic gain control to automatically set the microphone input volume
• Intelligent, configurable, adaptive queuing to automatically adjust to different and changing network conditions
• Integration with DirectSound, allowing for the application playback effects on a voice by voice basis such as 3-D positioning, reverb, etc.
• Capture focus to allow multiple DirectPlay Voice applications at once in the system
• Integration with DirectPlay for session and protocol level services