It is quite common to play games over IM networks. Since Tic-tac-toe is a well-known and simple game, it's a good example for a server-based game protocol.
This document addresses the requirements for a game protocol as defined by Multi-User Gaming . In particular this consists of:
The extensions needed to implement these requirements are qualified by the 'http://jabber.org/protocol/mug/tictactoe' namespace.
An entity implementing this protocol MUST also support Multi-User Gaming  and answer to disco requests accordingly including both the Multi-User Gaming and the game <feature/> elements in the response.
A Tic-tac-toe game uses two game roles, "x" and "o". Both roles have to be assigned to exactly one player to start a match. If one role gets unassigned or a player gets unavailable the match has to be paused.
A service SHOULD offer a configuration form with the following options:
An implementation MUST be able to handle the a board with three cols and rows and three respective marks to win. Everything beyond that is OPTIONAL.
Submitting a strike option value bigger than the number of rows or columns SHOULD result in <not-acceptable/> error.
The state in a Tic-tac-toe match represents the match configuration, the player who makes the next turn and the current state of the board. Every state is distributed to all occupants.
After a valid turn, the state gets updated with the corresponding mark.
The match is considered terminated when the board is full or when one player reaches the number of respective marks as defined by the strike option. After termination the service broadcasts the final state including either a <draw> or <won> (including a game role) element to indicate the resulting score and the initial state of the next round.
During the game, players change in turn, each of them MUST send only one move at a time. It MUST possess these attributes:
|'id'||REQUIRED||The number of the move. First move is 1.|
|'row'||REQUIRED||The horizontal position of the mark.|
|'col'||REQUIRED||The vertical position of the mark.|
The author is not aware of any security issues introduced by this protocol extension.
This document requires no interaction with the Internet Assigned Numbers Authority (IANA) .
The XMPP Registrar  shall include 'http://jabber.org/protocol/mug/tictactoe' in its registry of protocols.
This document in other formats: XML PDF
This XMPP Extension Protocol is copyright © 1999 – 2020 by the XMPP Standards Foundation (XSF).
Permission is hereby granted, free of charge, to any person obtaining a copy of this specification (the "Specification"), to make use of the Specification without restriction, including without limitation the rights to implement the Specification in a software program, deploy the Specification in a network service, and copy, modify, merge, publish, translate, distribute, sublicense, or sell copies of the Specification, and to permit persons to whom the Specification is furnished to do so, subject to the condition that the foregoing copyright notice and this permission notice shall be included in all copies or substantial portions of the Specification. Unless separate permission is granted, modified works that are redistributed shall not contain misleading information regarding the authors, title, number, or publisher of the Specification, and shall not claim endorsement of the modified works by the authors, any organization or project to which the authors belong, or the XMPP Standards Foundation.
## NOTE WELL: This Specification is provided on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, express or implied, including, without limitation, any warranties or conditions of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A PARTICULAR PURPOSE. ##
In no event and under no legal theory, whether in tort (including negligence), contract, or otherwise, unless required by applicable law (such as deliberate and grossly negligent acts) or agreed to in writing, shall the XMPP Standards Foundation or any author of this Specification be liable for damages, including any direct, indirect, special, incidental, or consequential damages of any character arising from, out of, or in connection with the Specification or the implementation, deployment, or other use of the Specification (including but not limited to damages for loss of goodwill, work stoppage, computer failure or malfunction, or any and all other commercial damages or losses), even if the XMPP Standards Foundation or such author has been advised of the possibility of such damages.
This XMPP Extension Protocol has been contributed in full conformance with the XSF's Intellectual Property Rights Policy (a copy of which can be found at <https://xmpp.org/about/xsf/ipr-policy> or obtained by writing to XMPP Standards Foundation, P.O. Box 787, Parker, CO 80134 USA).
The Extensible Messaging and Presence Protocol (XMPP) is defined in the XMPP Core (RFC 6120) and XMPP IM (RFC 6121) specifications contributed by the XMPP Standards Foundation to the Internet Standards Process, which is managed by the Internet Engineering Task Force in accordance with RFC 2026. Any protocol defined in this document has been developed outside the Internet Standards Process and is to be understood as an extension to XMPP rather than as an evolution, development, or modification of XMPP itself.
The primary venue for discussion of XMPP Extension Protocols is the <email@example.com> discussion list.
Discussion on other xmpp.org discussion lists might also be appropriate; see <http://xmpp.org/about/discuss.shtml> for a complete list.
Errata can be sent to <firstname.lastname@example.org>.
The following requirements keywords as used in this document are to be interpreted as described in RFC 2119: "MUST", "SHALL", "REQUIRED"; "MUST NOT", "SHALL NOT"; "SHOULD", "RECOMMENDED"; "SHOULD NOT", "NOT RECOMMENDED"; "MAY", "OPTIONAL".
1. XEP-xxxx: Multi-User Gaming <http://pidgin-games.sourceforge.net/xep/multi-user_gaming.html>.
2. The Internet Assigned Numbers Authority (IANA) is the central coordinator for the assignment of unique parameter values for Internet protocols, such as port numbers and URI schemes. For further information, see <http://www.iana.org/>.
3. The XMPP Registrar maintains a list of reserved protocol namespaces as well as registries of parameters used in the context of XMPP extension protocols approved by the XMPP Standards Foundation. For further information, see <https://xmpp.org/registrar/>.
Note: Older versions of this specification might be available at http://xmpp.org/extensions/attic/