Networked Virtual Simulation
Networked Virtual Simulations typically cooperatively simulate real-world entities or systems. Each simulate some portion of "real-world." They exchange data via network messages using standardized protocols:
- Simulation, e.g., SIMNET, DIS, ALSP, HLA (see notes)
- Network, e.g., TCP/IP, VoIP, UDP (see notes)
Notes:
- SIMNET: Simulation Networking
- DIS: Distributed Interactive Simulation
- ALSP: Aggregate Level Simulation Protocol
- HLA: High Level Architecture
- TCP/IP: Transmission Control Protocol over Internet Protocol
- VoIP: Voice over Internet Protocol
- UDP: User Datagram Protocol
A simulation protocol is the format and procedure that governs the transmitting and receiving of data. The term comes from the Greek "protokollon," which was the cover page to a manuscript that provided a description of the contents. Proto means “the first” and kolla means “to glue together.”
In order for computers to exchange information, there must be a preexisting agreement as to how the information will be structured and how each side will send and receive it. Without a protocol, a transmitting computer, for example, could be sending its data in 8-bit packets while the receiving computer might expect the data in 16-bit packets. Protocols are established by international or industry-wide organizations.
TCP/IP and Ethernet
The Transmission Control Protocol (TCP) is a virtual circuit protocol that is one of the core protocols of the Internet protocol suite, often simply referred to as TCP/IP. Using TCP, applications on networked hosts can create connections to one another, over which they can exchange streams of data. The protocol guarantees reliable and in-order delivery of data from sender to receiver. TCP also distinguishes data for multiple connections by concurrent applications (e.g., Web server and e-mail server) running on the same host.
Steel Beast is a highly accurate simulator of the US M1A1 and German Leopard 2A4 tanks designed to let you create and play scenarios of modern warfare. Scenarios can be played in either single-player mode against the computer, or in a multiplayer-mode against (and with) other players over a network. Steel Beast uses TCP/IP over a LAN. In 2002, I used Steel Beasts to train teams of US Military Cadets in Heavy/Mechanized Platoon tactics.
The TCP/IP Protocol
Are you there? Yes, I am. Are you ready to receive? Yes, I am. Here comes the message--blah, blah, blah-- did you get it? Yes, I did. Here comes the next part--blah, blah, blah-- did you get it? No, I didn't - resend it. Here it comes again-- blah, blah, blah-- did you get it? Yes, I did. There is no more. Goodbye. Goodbye.
The Ethernet Access Method
Is the network busy? Yes, it is. Wait random amount of time. Is the network busy? Yes, it is. Wait random amount. Is the network busy? No, it isn't. Here goes the frame... did it collide with another packet on the line? No, it didn't. Is the network busy? Yes, it is. Wait random amount. Is the network busy? No, it isn't. Here goes the next frame... did it collide? Yes, it did. Wait random amount. Is the network busy? No, it isn't. Here goes the frame again... did it collide?
User Datagram Protocol (UDP)
UDP, documented in RFC 768, provides users access to IP-like services. UDP packets are delivered just like IP packets, except they are connectionless datagrams that may be discarded before reaching their targets. UDP is useful when TCP would be too complex, too slow, or just unnecessary. UDP provides a few functions beyond that of IP:
- Port Numbers. UDP provides 16-bit port numbers to let multiple processes use UDP services on the same host. A UDP address is the combination of a 32-bit IP address and the 16-bit port number.
- Checksumming. Like IP, UDP does checksum its data, ensuring data integrity. A packet failing checksum is simply discarded, with no further action taken. However, in UDP the checksum is not required.
So we can see from the above that not having the extra twelve bytes of overhead in the UDP header does indeed make a substantial difference. This would account for the lack of “connection orientation” for UDP. You may note, that we also have a checksum in the header for UDP. All of the four core protocols, those being; IP, TCP, UDP, ICMP all have checksums. In all of the four core protocols the checksum will cover the protocol header and any data, if present. One of the last things I would like to mention about UDP and its checksum is that its use is optional. In essence, it does not have to be used, whereas in TCP, ICMP, and IP, it does.This protocol is connectionless, meaning when the server sends information to a connected player it does not wait for a confirmation that the information was received. This prevents the server from worrying about whether a connected player is receiving information or not. Have you ever played an online shooter game and found yourself eliminated before you knew you where threatened. Welcome to UDP--fast but unforgiving.
America's Army
America's Army (also known as AA or Army Game Project) is a tactical multiplayer first-person shooter owned by the United States Government and released as a global public relations initiative to help with U.S. Army recruitment.
Since July 4, 2002, America's Army has published 9 game releases; offering new game features and simulated training and missions. Each release has provided the America's Army community a virtual Army experience with a careful balance between authentic realism and virtual gaming fun.
The PC version, subtitled "Recon", was first released on July 4, 2002. Subsequently "Operations" was first released on July 12, 2002. Interim versions are listed below. The Xbox version was released in November, 2005. Version 2.8, "Coalition", debuted Dec 21, 2006 and has had many upgrades since Recon. It was financed through U.S. tax dollars and distributed for free. The latest version 3.0 "Special Forces" was released on June 17, 2009.
The Unreal Engine
The Unreal Engine is a widely-used game engine developed by Epic Games. First illustrated in the 1998 first-person shooter game Unreal, it has been the basis of many games since, including Unreal Tournament , Tom Clancy's Rainbow Six 3: Raven Shield, Red Steel , and Gears of War. Although primarily developed for first-person shooters, it has been successfully utilized in a variety of genres, including 3rd-person stealth (Tom Clancy's Splinter Cell) and MMORPG (Vanguard: Saga of Heroes).
Its core written in C++, the Unreal Engine features a high degree of portability, supporting a plethora of platforms including the IBM PC compatibles (Microsoft Windows, GNU/Linux), Apple Macintosh (Mac OS, Mac OS X) and many consoles (Dreamcast, Xbox, Xbox 360, Playstation 2, Playstation 3). A great deal of the gameplay code is written in UnrealScript, a proprietary scripting language, and as such large parts of the gameplay can be modified without delving deep into the engine internals. Additionally, as with other middleware packages, the Unreal Engine also provides various tools to assist with content creation, both for designers and artists.
Unreal Engine 2 (America’s Army v1.0 ~ v2.x)
The sophomore version of the Unreal Engine got off to a rocky start with the mixed reviews for Unreal Tournament 2003. This generation saw the core code and rendering engine completely re-written and the new UnrealEd 3 integrated. It also integrated the Karma physics software development kit (SDK), which powered the vehicles in Unreal Tournament 2004. Many other engine elements were also updated, with improved and added support for the PlayStation 2 and the Xbox, respectively.
Unreal Engine 3 (America's Army v 3.x)
In America's Army 3, Every Detail Counts and as a result, the game has more authentic military elements including training, technology, weapons, and audio than any other military game. Built on Unreal Engine 3, AA3 delivers stunningly realistic environments, lighting effects, animations, and team-based experiences so that America's Army players can experience how Soldiers train, live, and advance in the Army. Players are bound by Rules of Engagement (ROE) and gain experience as they navigate challenges in team-based, multiplayer, force-on-force operations. In the game, a player's actions and demonstrated Army values are integral to successful mission accomplishment and affect a player's career progression.
Version History
- America's Army 3: (version 3.0.7) 18 FEB 2010
- AA3.0.6 Hot Fix Released (v3.0.6 Hot Fix) 17 SEP 2009
- AA3.0.6 Update Released (v3.0.6) 07 SEP 2009
- AA3.0.5 Update Released (v3.0.5) 13 JUL 2009
- America's Army 3: Patch (Version 3.0.4) 03 JUL 2009
- AA3.0.3 Hot Fix Released (v3.0.3) 24 JUN 2009
- AA3.0.2 Hot Fix Released (v3.0.2) 19 JUN 2009
- AA3.0.1 Hot Fix Released (v3.0.1) 18 JUN 2009
- America's Army 3 PC Action Game (v3.0.0) 17 JUN 2009
- America's Army : Special Forces (Overmatch) (Version 2.8.5) April 30th 2009
- America's Army : Special Forces (Overmatch) (Version 2.8.4) October 6th 2008
- America's Army : Special Forces (Overmatch) (Version 2.8.3.1) March 25th 2008
- America's Army : Special Forces (Overmatch) (Version 2.8.3) January 31st 2008
- America's Army : Special Forces (Overmatch) (Version 2.8.2) Septmber 6th 2007
- America's Army : Special Forces (Overmatch) (Version 2.8.1) March 22nd 2007
- America's Army: Special Forces (Coalition) (version 2.8) December 21st 2006
- America's Army: Special Forces (Overmatch) (Version 2.7.0) September 14th 2006
- America's Army: Special Forces (Link-Up) (Version 2.6.0) February 8th 2006
- America's Army: Special Forces (Direct Action) (Version 2.5.0) September 6th 2005
- America's Army: Special Forces (Q-Course) (Version 2.4.0) May 18th 2005
- America's Army: Special Forces (Firefight) (Version 2.3.0) February 18th 2005
- America's Army: Special Forces (Vanguard) (Version 2.2.1) November 18th 2004
- America's Army: Special Forces (Vanguard) (Version 2.2.0) October 19th 2004
- America's Army: Special Forces (Downrange) (Version 2.1.0) June 1st 2004
- America's Army: Special Forces (Sandstorm) (Version 2.0.0a) December 21st 2003
- America's Army: Special Forces (Version 2.0) November 6th 2003
- America's Army: Operations (Medics) (v1.9.0)) 08 AUG 2003
- America's Army: Operations (Bridge SE) (v1.7.0) 21 APR 2003
- America's Army: Operations (Radio Tower) (v1.6.0) 16 MAR 2003
- America's Army: Operations (Weapons Cache SE) (v1.5.0) 23 DEC 2002
- America's Army: Operations (River Basin) (v1.4.0) 25 NOV 2002
- America's Army: Operations (Mountain Pass) (v1.3.0) 10 OCT 2002
- America's Army: Operations (Map Pack) (v1.2.1) 03 OCT 2002
- America's Army: Operations (Airborne Pack) (v1.2.0) 22 AUG 2002
- America's Army: Operations (Marksmanship Pack) (v1.1.1) 01 AUG 2002
- America's Army: Operations (v1.0.1b) 05 JUL 2002
- America's Army: Recon (v1.0.0) 04 JUL 2002
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