Difference between revisions of "Standards:GMCP Client Variables"

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== GMCP Client Variables Sharing Standard ==
 
  
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=== Overview and Rationale ===
 
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The GMCP Client Variables Sharing extension provides a standardized way to exchange client-specific variables between MUD clients and game servers using GMCP messages. This facilitates enhanced user experiences by allowing servers to adjust gameplay and UI elements based on client-provided data.
 
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====Rationale====
 
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As MUDs become more complex, the need for customizable and dynamic interactions between clients and servers has grown. Sharing client-specific variables allows for personalized gameplay experiences, seamless UI adjustments, and improved accessibility features. By standardizing this exchange, the GMCP Client Variables Sharing extension ensures that all participants in the MUD ecosystem can benefit from enhanced communication and data sharing.
 
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====Consent Management Process====
 
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A critical aspect of sharing client-specific variables is obtaining user consent. This process ensures that users are aware of what data is being shared and have control over their personal information. This exchange of information is geared towards finding out what data is available in the client, receiving only what is needed from the server or script, and prompting the user for fields where consent is necessary and the fields are desired.
 
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=== Specification for Client.Variables ===
 
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==== Commands ====
 
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===== Client.Variables.Default =====
 
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'''Purpose''': <code>Client.Variables.Default</code> is sent by the server to acknowledge support for the Client.Variables namespace. The client will synchronously respond with a <code>Client.Variables.List</code> message.
 
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<syntaxhighlight lang="json">
 
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Client.Variables.Default {}
 
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</syntaxhighlight>
 
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===== Client.Variables.List =====
 
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'''Purpose''': The client sends an array of available client variables and their attributes with <code>Client.Variables.List</code>. The server may asynchronously respond with a <code>Client.Variables.Request</code> message.
 
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======Attribute Details======
 
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{| class="wikitable “wikitable”"
 
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|-
 
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!Attribute
 
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!Description
 
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!Value
 
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!Required
 
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|-
 
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|'''''name'''''
 
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|Client variable identifier.
 
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|(text)
 
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|Yes
 
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|-
 
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|'''''available'''''
 
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|Indicates if the variable is available for use. Values that require consent default to <code>false</code>.
 
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|<code>true</code> or <code>false</code>
 
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|Yes
 
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|-
 
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|'''''updatable'''''
 
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|Indicates if the variable can be updated by the server.
 
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|<code>true</code> or <code>false</code>
 
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|Yes
 
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|}
 
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<syntaxhighlight lang="json">
 
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Client.Variables.List [
 
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    {"name": "256_COLORS", "available": true, "updatable": false},
 
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    {"name": "ANSI", "available": true, "updatable": false},
 
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    {"name": "BOLD_IS_BRIGHT", "available": true, "updatable": true},
 
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    {"name": "CHARSET", "available": true, "updatable": true},
 
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    {"name": "CLIENT_NAME", "available": true, "updatable": false},
 
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    {"name": "CLIENT_VERSION", "available": true, "updatable": false},
 
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    {"name": "LANGUAGE", "available": false, "updatable": false},
 
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    {"name": "MTTS", "available": true, "updatable": false},
 
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    {"name": "OSC_COLOR_PALETTE", "available": true, "updatable": false},
 
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    {"name": "SCREEN_READER", "available": false, "updatable": false},
 
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    {"name": "SYSTEMTYPE", "available": false, "updatable": false},
 
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    {"name": "TERMINAL_TYPE", "available": true, "updatable": false},
 
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    {"name": "TLS", "available": true, "updatable": false},
 
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    {"name": "TRUECOLOR", "available": true, "updatable": false},
 
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    {"name": "USER", "available": false, "updatable": false},
 
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    {"name": "UTF-8", "available": true, "updatable": false},
 
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    {"name": "VT100", "available": true, "updatable": false},
 
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    {"name": "WORD_WRAP", "available": true, "updatable": false}
 
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]
 
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</syntaxhighlight>
 
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=====Client.Variables.Request=====
 
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'''Purpose''': The server requests specific client variables with <code>Client.Variables.Request</code>. The client will synchronously respond with a <code>Client.Variables.Update</code> message.
 
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To encourage consent to collect personal information, custom messages to describe the reason for collecting the information may be included for the client to display with the <code>purpose</code> attribute.
 
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Limit the value for <code>purpose</code> to 250 characters or less.
 
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======Attribute Details======
 
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{| class="wikitable “wikitable”"
 
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|-
 
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! Attribute
 
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!Description
 
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!Value
 
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!Required
 
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|-
 
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|'''''name'''''
 
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|Client variable identifier.
 
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|(text)
 
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|Yes
 
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|-
 
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|'''''purpose'''''
 
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|Reason for collecting the information.
 
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|(text)
 
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|No
 
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|}
 
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<syntaxhighlight lang="json">
 
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Client.Variables.Request [
 
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    {"name": "BOLD_IS_BRIGHT"},
 
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    {"name": "CHARSET"},
 
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    {"name": "LANGUAGE", "purpose": "Match client language to adjust game and user interface content"},
 
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    {"name": "SCREEN_READER", "purpose": "Enable accessible features to adjust game and user interface content"},
 
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    {"name": "SYSTEMTYPE", "purpose": "Consider client operating system to adjust game and user interface elements"},
 
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    {"name": "USER", "purpose": "Indicate client account:character name to the game server"}
 
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]
 
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</syntaxhighlight>
 
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=====Client.Variables.Update=====
 
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'''Purpose''': The client sends updates for requested variables with <code>Client.Variables.Update</code>. These are sent with a <code>source</code> attribute of <code>request</code> in response to <code>Client.Variables.Request</code>. A <code>source</code> of <code>client</code> will be sent when updates occur in the client, such as changing a requested variable in the client's menu. A <code>source</code> of <code>server</code> will be sent in response to <code>Client.Variables.Set</code>, which is initiated by the server.
 
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======Attribute Details ======
 
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{| class="wikitable “wikitable”"
 
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|-
 
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!Attribute
 
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!Description
 
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!Value
 
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!Required
 
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|-
 
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|'''''name'''''
 
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|Client variable identifier.
 
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|(text)
 
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|Yes
 
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|-
 
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|'''''available'''''
 
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| Indicates if the variable is available for use.
 
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|<code>true</code> or <code>false</code>
 
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|Yes
 
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|-
 
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|'''''updatable'''''
 
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|Indicates if the variable can be updated by the server.
 
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|<code>true</code> or <code>false</code>
 
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|Yes
 
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|-
 
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|'''''requested'''''
 
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|Indicates if the variable was requested by the server.
 
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|<code>true</code> or <code>false</code>
 
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|Yes
 
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|-
 
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|'''''source'''''
 
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|Indicates the source of the update.
 
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|<code>request</code> or <code>client</code> or <code>server</code>
 
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| Yes
 
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|-
 
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|'''''timestamp'''''
 
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|Unix timestamp indicating when the update was made.
 
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|10-digit (or less) number
 
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|Yes
 
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|-
 
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|'''''success'''''
 
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|Indicates if an updatable variable changed.
 
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|<code>true</code> or <code>false</code>
 
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|Only sent in response to Client.Variables.Set messages.
 
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|-
 
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|'''''value'''''
 
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|The value of the variable.
 
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|
 
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| When '''''available''''' is <code>true</code>and a value exists.
 
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|}
 
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<syntaxhighlight lang="json">
 
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Client.Variables.Update [
 
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    {"name": "BOLD_IS_BRIGHT", "available": true, "updatable": true, "requested": false, "source": "request", "timestamp": 1721495879, "value": 2},
 
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    {"name": "CHARSET", "available": true, "updatable": true, "requested": false, "source": "request", "timestamp": 1721495879, "value": "UTF-8"},
 
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    {"name": "LANGUAGE", "available": false, "updatable": false, "requested": true, "source": "request", "timestamp": 1721495879},
 
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    {"name": "SCREEN_READER", "available": false, "updatable": false, "requested": true, "source": "request", "timestamp": 1721495879},
 
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    {"name": "SYSTEMTYPE", "available": false, "updatable": false, "requested": true, "source": "request", "timestamp": 1721495879},
 
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    {"name": "USER", "available": false, "updatable": false, "requested": true, "source": "request", "timestamp": 1721495879}
 
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]
 
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</syntaxhighlight>
 
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=====Client.Variables.Set=====
 
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'''Purpose''': The server sets one or more previously requested, updatable client variables with <code>Client.Variables.Set</code>. The client will synchronously respond with a Client.Variables.Update with a <code>source</code> attribute of <code>server</code>.
 
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======Attribute Details======
 
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{| class="wikitable “wikitable”"
 
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|-
 
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! Attribute
 
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!Description
 
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!Value
 
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! Required
 
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|-
 
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|'''''name'''''
 
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| Client variable identifier.
 
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|(text)
 
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| Yes
 
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|-
 
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|'''''value'''''
 
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|The value of the variable.
 
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|(varies)
 
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|Yes
 
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|}
 
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<syntaxhighlight lang="json">
 
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// Client request with a valid and invalid value
 
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Client.Variables.Set [
 
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    {"name": "BOLD_IS_BRIGHT", "value": 1},
 
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    {"name": "CHARSET", "value": "DEEP-6"}
 
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]
 
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// Server response to a valid and invalid value
 
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Client.Variables.Update [
 
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    {"name": "BOLD_IS_BRIGHT", "available": true, "updatable": true, "source": "server", "timestamp": 1721495900, "success": true, "value": 1},
 
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    {"name": "CHARSET", "available": true, "updatable": true, "source": "server", "timestamp": 1721495900, "success": false, "value": "DEEP-6"}
 
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]
 
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</syntaxhighlight>
 
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===Implementation Considerations===
 
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*'''Client Support Advertisement''': Clients should advertise their support for the Client.Variables namespace using <code>Core.Supports.Set</code>.
 
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*'''Server Acknowledgement''': Servers acknowledge support with <code>Client.Variables.Default</code>.
 
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*'''Consent Management''': Clients must handle user consent for sharing sensitive or personal data variables. Prompts should inform users of requested data and allow them to opt-in or block requests.
 
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*'''Blocked Variables''': Clients should not share a variable previously blocked by a user in <code>Client.Variables.List</code> messages, nor make the variable available to other protocols, such as NEW-ENVIRON, MNES, and MTTS.
 
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*'''Variable Naming Convention''': Variables should be transferred in uppercase to maintain consistency and avoid issues with case sensitivity.
 
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*'''Legacy Support''': Game drivers may not be able to send boolean values. Where boolean values are expected, clients will transform <code>"true"</code> or <code>1</code> to <code>true</code>, and <code>"false"</code> or <code>0</code> to <code>false</code>.
 
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===Example Flow===
 
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1. '''Client''': Should advertise support.
 
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<syntaxhighlight lang="json">
 
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Core.Supports.Set ["Client.Variables 1", ...]
 
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</syntaxhighlight>
 
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2. '''Server''': May acknowledge support.
 
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<syntaxhighlight lang="json">
 
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Client.Variables.Default {}
 
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</syntaxhighlight>
 
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3. '''Client''': Must send available variables list. Variables previously blocked by the user should not be sent.
 
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<syntaxhighlight lang="json">
 
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Client.Variables.List [
 
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    {"name": "256_COLORS", "available": true, "updatable": false},
 
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    {"name": "ANSI", "available": true, "updatable": false},
 
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    {"name": "BOLD_IS_BRIGHT", "available": true, "updatable": true},
 
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    {"name": "CHARSET", "available": true, "updatable": true},
 
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    {"name": "CLIENT_NAME", "available": true, "updatable": false},
 
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    {"name": "CLIENT_VERSION", "available": true, "updatable": false},
 
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    {"name": "LANGUAGE", "available": false, "updatable": false},
 
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    {"name": "MTTS", "available": true, "updatable": false},
 
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    {"name": "OSC_COLOR_PALETTE", "available": true, "updatable": false},
 
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    {"name": "SCREEN_READER", "available": false, "updatable": false},
 
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    {"name": "SYSTEMTYPE", "available": false, "updatable": false},
 
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    {"name": "TERMINAL_TYPE", "available": true, "updatable": false},
 
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    {"name": "TLS", "available": true, "updatable": false},
 
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    {"name": "TRUECOLOR", "available": true, "updatable": false},
 
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    {"name": "USER", "available": false, "updatable": false},
 
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    {"name": "UTF-8", "available": true, "updatable": false},
 
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    {"name": "VT100", "available": true, "updatable": false},
 
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    {"name": "WORD_WRAP", "available": true, "updatable": false}
 
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]
 
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</syntaxhighlight>
 
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4. '''Server''': May requests specific variables. Once per connected session, the client may prompt the user with a request to share variables that are <code>"available": false</code> from the <code>Client.Variables.List</code> message.<syntaxhighlight lang="json">
 
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Client.Variables.Request [
 
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    {"name": "BOLD_IS_BRIGHT"},
 
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    {"name": "CHARSET"},
 
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    {"name": "LANGUAGE", "purpose": "Match client language to adjust game and user interface content"},
 
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    {"name": "SCREEN_READER", "purpose": "Enable accessible features to adjust game and user interface content"},
 
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    {"name": "SYSTEMTYPE", "purpose": "Consider client operating system to adjust game and user interface elements"},
 
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    {"name": "USER", "purpose": "Indicate client account:character name to the game server"}
 
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]
 
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</syntaxhighlight>
 
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5. '''Client''': Updates requested variables.
 
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<syntaxhighlight lang="json">
 
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Client.Variables.Update [
 
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    {"name": "BOLD_IS_BRIGHT", "available": true, "updatable": true, "requested": false, "source": "request", "timestamp": 1721495879, "value": 2},
 
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    {"name": "CHARSET", "available": true, "updatable": true, "requested": false, "source": "request", "timestamp": 1721495879, "value": "UTF-8"},
 
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    {"name": "LANGUAGE", "available": false, "updatable": false, "requested": true, "source": "request", "timestamp": 1721495879},
 
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    {"name": "SCREEN_READER", "available": false, "updatable": false, "requested": true, "source": "request", "timestamp": 1721495879},
 
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    {"name": "SYSTEMTYPE", "available": false, "updatable": false, "requested": true, "source": "request", "timestamp": 1721495879},
 
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    {"name": "USER", "available": false, "updatable": false, "requested": true, "source": "request", "timestamp": 1721495879}
 
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]
 
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</syntaxhighlight>
 
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====Flow Diagrams====
 
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======Requesting and Receiving Variables======
 
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[[File:Flow1.png|alt=GMCP Client Variables Flow 1|frameless|600x600px]]
 
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======Receiving Variable Updates======
 
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[[File:Flow2.png|alt=GMCP Client Variables Flow 2|frameless|600x600px]]
 
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======Setting Updatable Variables======
 
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[[File:Flow3.png|alt=GMCP Client Variables Flow 3|frameless|600x600px]]
 
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===Conclusion===
 
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The GMCP Client Variables Sharing extension standardizes the exchange of client-specific variables, ensuring seamless integration and enhanced user experiences. By adopting this standard, MUD developers can streamline variable management, improve client-server communication, and provide more personalized gaming experiences.
 
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==Versions==
 
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*Version 1.0: Initial specification.
 
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==Authors==
 
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*Mike Conley (Tamarindo, Administrator at StickMUD and Mudlet contributor) mike.conley[at]stickmud.com
 
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===Notes===
 
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*This specification is subject to updates and community input. Contributions and feedback are welcome to ensure it meets the needs of the MUD community in the #mudlet-development channel of the Mudlet Discord.
 
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*Implementation should follow GMCP protocol specifications, and all messages must be well-formatted JSON objects.
 

Latest revision as of 19:30, 7 September 2024

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