Tighter definition for "otherConfig" in fdc3.chart context type

[rbruckheimer]

Enhancement Request

Use Case:

The otherConfig section of the fdc3.chart context type message allows additional directives to be sent to the resulting chart, such as indicators and annotations. As it stands now, all target applications that acknowledge otherConfig will attempt to digest its contents without actually knowing if it is intended for them. This can cause unintended consequences when a message tailored for one app is misinterpreted by another app.

Workflow Description

Rather than looking like this:

otherConfig: {
        indicators: [
            {
                name: "ma",
                parameters: {
                    period: 14,
                    type: "ema"
                }
            },
            {
                name: "volume"
            }
        ]
}

the otherConfig section ought to look like this:

otherConfig: {
        configs: [
            {
                type: "[vendor.product.indicator]"
                name: "ma",
                parameters: {
                    period: 14,
                    type: "ema"
                }
            },
            {
                type: "[vendor.product.indicator]"
                name: "volume"
            }
        ]
}

In this way, different products can digest only the configurations pertaining to them.

Workflow Examples

This block will send the same indicator to different vendors who process them differently:

otherConfig: {
	configs: [
		{
			type: "somevendor.someproduct.indicator",
			name: "stddev",
			parameters: {
				period: 10,
				matype: "exponential"
			}
		},
		{
			type: "someothervendor.someotherproduct.formula",
			formula: "standard-deviation",
			fields: {
				lookback: 10,
				type: "ema"
			}
		}
	]
}

Additional Information

Schema change:

"otherConfig": {
	"type": "object"
}

changes to:

"otherConfig": {
	"type": "object",
	"additionalProperties": { 
		"type": "array",
		"items": {
			"$ref": "context.schema.json#"
		} 
	}
}

[kriswest]

@rbruckheimer I think this would be cleaner without a redundant layer, i.e. do this:

otherConfig: [
    {
        type: "somevendor.someproduct.indicator",
	    ...
    },
    { ... }
]

rather than this:

otherConfig: {
	configs: [
		{
			type: "somevendor.someproduct.indicator",
			...
		},
		{ ... }
	]
}

I've implemented this in PR #985 - could you take a look and confirm that you are happy with that. You can see the docs preview for it at: https://deploy-preview-985--fdc3.netlify.app/docs/next/context/ref/Chart