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 [1]. 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 [1] and answer to disco requests accordingly including both the Multi-User Gaming and the game <feature/> elements in the response.
<iq type='result'
from='games.shakespeare.lit'
id='disco1'
to='juliet@capulet.com/garden'>
<query xmlns='http://jabber.org/protocol/disco#info'>
...
<feature var='http://jabber.org/protocol/mug'/>
<feature var='http://jabber.org/protocol/mug/tictactoe'/>
...
</query>
</iq>
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.
<iq from='tictactoe@games.shakespeare.lit'
id='config1'
to='juliet@capulet.com/garden'
type='result'>
<query xmlns='http://jabber.org/protocol/mug#owner'>
<options>
<x xmlns='jabber:x:data' type='form'>
<title>Tic-tac-toe Room</title>
...
</x>
<options xmlns='http://jabber.org/protocol/mug/tictactoe'>
<x xmlns='jabber:x:data' type='form'>
<title>Configuration for Tic-tac-toe</title>
<instructions>
Below you can see the default configuration.
To accept the default configuration, click OK.
To select a different configuration, please complete this form.
</instructions>
<field var='FORM_TYPE' type='hidden'>
<value>http://jabber.org/protocol/mug/tictactoe#tictactoeconfig</value>
</field>
<field label='Number of rows' var='mug/tictactoe#config_rows' type='list-single'>
<value>3</value>
<option label='3'><value>3</value></option>
<option label='4'><value>4</value></option>
<option label='5'><value>5</value></option>
<option label='6'><value>6</value></option>
<option label='7'><value>7</value></option>
<option label='8'><value>8</value></option>
<option label='9'><value>9</value></option>
<option label='10'><value>10</value></option>
</field>
<field label='Number of cols' var='mug/tictactoe#config_cols' type='list-single'>
<value>3</value>
<option label='3'><value>3</value></option>
<option label='4'><value>4</value></option>
<option label='5'><value>5</value></option>
<option label='6'><value>6</value></option>
<option label='7'><value>7</value></option>
<option label='8'><value>8</value></option>
<option label='9'><value>9</value></option>
<option label='10'><value>10</value></option>
</field>
<field label='Strike' var='mug/tictactoe#config_strike' type='list-single'>
<value>3</value>
<option label='3'><value>3</value></option>
<option label='4'><value>4</value></option>
<option label='5'><value>5</value></option>
<option label='6'><value>6</value></option>
<option label='7'><value>7</value></option>
<option label='8'><value>8</value></option>
<option label='9'><value>9</value></option>
<option label='10'><value>10</value></option>
</field>
<field label='Select a role who start the game' var='mug/tictactoe#config_first' type='list-single'>
<value>x</value>
<option label='x'><value>x</value></option>
<option label='o'><value>o</value></option>
</field>
</x>
</options>
</options>
</query>
</iq>
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.
<presence
from='tictactoe@games.shakespeare.lit'
to='juliet@capulet.com/garden'>
<game xmlns='http://jabber.org/protocol/mug'>
<status>inactive</status>
<state xmlns='http://jabber.org/protocol/mug/tictactoe'>
<rows>3</rows>
<cols>3</cols>
<strike>3</strike>
<next>x</next>
<board/>
</state>
</game>
</presence>
After a valid turn, the state gets updated with the corresponding mark.
<presence
from='tictactoe@games.shakespeare.lit'
to='juliet@capulet.com/garden'>
<game xmlns='http://jabber.org/protocol/mug'>
<status>active</status>
<state xmlns='http://jabber.org/protocol/mug/tictactoe'>
<rows>3</rows>
<cols>3</cols>
<strike>3</strike>
<next>o</next>
<board>
<field row='1' col='1'>x</field>
<field row='2' col='1'>o</field>
<field row='2' col='2'>x</field>
<field row='1' col='3'>o</field>
<field row='2' col='3'>x</field>
</board>
</state>
</game>
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.
<presence
from='tictactoe@games.shakespeare.lit'
to='juliet@capulet.com/garden'>
<game xmlns='http://jabber.org/protocol/mug'>
<status>inactive</status>
<state xmlns='http://jabber.org/protocol/mug/tictactoe'>
<rows>3</rows>
<cols>3</cols>
<strike>3</strike>
<next>o</next>
<board/>
<won>x</won>
</state>
</game>
</presence>
During the game, players change in turn, each of them MUST send only one move at a time. It MUST possess these attributes:
| Name | Type | Description |
| '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. |
<message
to='tictactoe@games.shakespeare.lit'
from='juliet@capulet.com/garden'
type='chat'>
<turn xmlns='http://jabber.org/protocol/mug#user'>
<move
xmlns='http://jabber.org/protocol/mug/tictactoe'
row='3'
col='2'
id='7'/>
</turn>
</message>
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) [2].
The XMPP Registrar [3] shall include 'http://jabber.org/protocol/mug/tictactoe' in its registry of protocols.
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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.
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Discussion on other xmpp.org discussion lists might also be appropriate; see <https://xmpp.org/community/> for a complete list.
Errata can be sent to <editor@xmpp.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 https://xmpp.org/extensions/attic/
First Draft.
@report{könig2009not yet assigned,
title = {Server-based Tic-tac-toe},
author = {König, Arne and Nieß, Günther},
type = {XEP},
number = {xxxx},
version = {0.0.1},
institution = {XMPP Standards Foundation},
url = {https://xmpp.org/extensions/xep-xxxx.html},
date = {2009-03-14/2009-03-14},
}END