1.3 Overview

This specification describes the reliable transport mechanism that can be used with the DirectPlay 4 Protocol. This mechanism provides for reliable delivery of messages, message throttling , and for applications written for the IDirectPlay4 interface. Early implementations of DirectPlay 4 did not provide reliable delivery and throttling. As a result, in some scenarios, no reliable delivery services were available. The reliable transport mechanism combines the reliable and unreliable delivery of messages into a single channel of data. This facilitates a single set of flow control logic that provides both reliable and unreliable data delivery services, as specified in [USPATENT6438603 B1].

The reliable transport mechanism used by the DirectPlay 4 Protocol is an envelope that encapsulates all messages sent between connected peers when active. That is, the mechanism becomes active when the normal DirectPlay 4 connection process has completed. All messages sent to the host during the connection process do not use the reliable transport mechanism.

The application determines whether the reliable transport mechanism is activated. Use of reliable transport is exclusive of the use of some of the normally available security functionality in DirectPlay 4. However, when reliable transport is activated, user-level security is not available.