1.1 Glossary
This document uses the following terms:
acknowledgment (ACK): A signal passed between communicating processes or computers to signify successful receipt of a transmission as part of a communications protocol.
coalesced payload: A special form of payload that consists of multiple traditional payloads combined into a single packet.
command frame (CFRAME): A special DirectPlay 8 control frame that does not carry application payload data. For more information, see the DirectPlay 8 Protocol: Reliable Specification ([MC-DPL8R] section 2.2.1). See Also, data frame.
data frame (DFRAME): A DirectPlay 8 frame that exists in the standard connection sequence space and typically carries application payload data. The total size of the DFRAME header and payload should be less than the Maximum Transmission Unit (MTU) of the underlying protocols and network. For more information, see the DirectPlay 8 Protocol: Reliable Specification ([MC-DPL8R] section 2.2.2). See Also, command frame.
DirectX: Microsoft DirectX is a collection of application programming interfaces for handling tasks related to multimedia, especially game programming and video, on Microsoft platforms.
DirectX runtime: A set of libraries created for the family of Windows operating systems that provide interfaces to ease the development of video games.
game: An application that uses a DirectPlay protocol to communicate between computers.
game session: The metadata associated with the collection of computers participating in a single instance of a computer game.
Internet Protocol security (IPsec): A framework of open standards for ensuring private, secure communications over Internet Protocol (IP) networks through the use of cryptographic security services. IPsec supports network-level peer authentication, data origin authentication, data integrity, data confidentiality (encryption), and replay protection.
little-endian: Multiple-byte values that are byte-ordered with the least significant byte stored in the memory location with the lowest address.
local area network (LAN): A group of computers and other devices dispersed over a relatively limited area and connected by a communications link that enables any device to interact with any other device on the network.
maximum transmission unit (MTU): The size, in bytes, of the largest packet that a given layer of a communications protocol can pass onward.
next receive: The next 8-bit packet sequence ID expected to be received, indicating acknowledgment of all packets up to this ID. This is typically represented as a field named bNRcv in packet structures. See Also, next send.
next send: The next 8-bit packet sequence ID that will be sent. This is represented as bNSeq in the selective acknowledgment packet structure, which does not have a sequence ID of its own. DirectPlay 8 protocol implementations also keep an internal counter so that IDs can be assigned in order. See Also, next receive.
partner: A computer connected to a local computer through either inbound or outbound connections.
payload: The data that is transported to and from the application that is using either the DirectPlay 4 protocol or DirectPlay 8 protocol.
peer-to-peer: A server-less networking technology that allows several participating network devices to share resources and communicate directly with each other.
player: A person who is playing a computer game. There can be multiple players on a computer participating in any given game session. See also name table.
round-trip time (RTT): The time that it takes a packet to be sent to a remote partner and for that partner's acknowledgment to arrive at the original sender. This is a measurement of latency between partners.
selective acknowledgment (SACK): A cumulative mechanism that indicates successful receipt of packets beyond the next receive indicator. Next receive reports all packets prior to when its sequence ID has been received, but subsequent packets can arrive out of order or with gaps in the sequence. SACK masks enable the receiver to acknowledge these packets so that they do not have to be retried, in addition to the packets that were truly lost. See also acknowledgment (ACK), next receive, and next send.
send mask: A bitmask mechanism indicating that previously sent packets might have been dropped, were not marked as reliable, and will never be retried.
sequence ID: A monotonically increasing 8-bit identifier for packets. This is typically represented as a field named bSeq in packet structures.
tick count: In DirectPlay, the count from when the system was booted, in milliseconds.
Transmission Control Protocol (TCP): A protocol used with the Internet Protocol (IP) to send data in the form of message units between computers over the Internet. TCP handles keeping track of the individual units of data (called packets) that a message is divided into for efficient routing through the Internet.
User Datagram Protocol (UDP): The connectionless protocol within TCP/IP that corresponds to the transport layer in the ISO/OSI reference model.
MAY, SHOULD, MUST, SHOULD NOT, MUST NOT: These terms (in all caps) are used as defined in [RFC2119]. All statements of optional behavior use either MAY, SHOULD, or SHOULD NOT.