Updating request-response logging structure

[SachinVarghese]

Update Request Logger for Text, Image, Tabular prefix
Related to https://github.com/SeldonIO/seldon-deploy/issues/460

[seldondev]

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[SachinVarghese]

New log format

{
	"request": {
		"dataType": "tabular",
		"tabular": {
			"meta": {
				"puid": "45q10f52lodc0sqb86udsvn7a7"
			},
			"data": {
				"names": ["Age", "Workclass", "Education", "Marital Status", "Occupation", "Relationship", "Race", "Sex", "Capital Gain", "Capital Loss", "Hours per week", "Country"],
				"ndarray": [
					[22.0, 7.0, 1.0, 1.0, 1.0, 1.0, 4.0, 1.0, 2174.0, 0.0, 40.0, 4.0]
				]
			},
			"dataType": "tabular"
		}
	},
	"response": {
		"dataType": "tabular",
		"tabular": {
			"meta": {
				"puid": "45q10f52lodc0sqb86udsvn7a7",
				"requestPath": {
					"income-default": "seldonio/sklearnserver_rest:0.2"
				}
			},
			"data": {
				"names": ["t:0", "t:1"],
				"ndarray": [
					[1.0, 0.0]
				]
			},
			"dataType": "tabular"
		}
	},
	"sdepName": "income",
	"namespace": "default",
	"request_elements": {
		"Age": [22.0],
		"Workclass": [7.0],
		"Education": [1.0],
		"Marital Status": [1.0],
		"Occupation": [1.0],
		"Relationship": [1.0],
		"Race": [4.0],
		"Sex": [1.0],
		"Capital Gain": [2174.0],
		"Capital Loss": [0.0],
		"Hours per week": [40.0],
		"Country": [4.0]
	},
	"response_elements": {
		"t:0": [1.0],
		"t:1": [0.0]
	}
}

[ryandawsonuk]

This is definitely an improvement. It should resolve the problem we were having that if we ran a request with tabular float data first then fields could be inferred by elastic as float type and this would then lead to failures on a request for a string/text type.

There might in the future be a risk where two different models use tabular data and a field has the same name but a different type. That could lead to another type conflict. But that is much less likely and if were to happen then renaming one of the fields would address it.