Supported OpenAPI (Off-chain Kernel)

The below table explains the OpenAPI schemas that KRNL currently supports.

To read more about OpenAPI, explore the below hyperlink.

What Is OpenAPI?Swagger Docs

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Important Notes

1. Using AI Tools

One important note here is that if you are generating OpenAPI Specification by using AI, the schema might be misaligned.

Be careful and make sure that the schema matches with this guide to avoid paying for the gas during registration on the wrong schema.

2. Single API Endpoint

With the current architecture of KRNL, the Web APIs that can be registered as off-chain kernels have to be a single API Endpoint.

3. HTTP Request Method

Currently we do support only GET and POST method for calling off-chain kernels

• GET

• POST

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There are various approaches to constructing and writing OpenAPI schema specifications. While some schemas are compatible with our technology, others may require small modifications.

While OpenAPI 3.0.x might be eligible, we do recommend using OpenAPI version 3.1.x.

The schema that is not defined in this page may not work with our architecture.

Element	Example	Description
null value	//... "type": "string", "nullable": true //...	This is the only correct way to handle null value on OpenAPI 3.0 Specification. Other methods might be from the older version. There is a caveat when working with null value, please checkout anyOf section.
anyOf	Check anyOf section	Some cases are supported Click here to read more
oneOf	Check oneOf section	Some cases are supported Click here to read more
allOf	not supported at the moment	-
Enumeration	Check Enum section	Click here to read more

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anyOf

Supported Schema

When it comes to the schemas that have "anyOf" element, KRNL node can support some specific cases.

anyOf with null under "components"

JSON

// ...
"components": {
    "schemas": {
        "Foo": {
            "properties": {
                "address": {
                    "anyOf": [
                    {
                        "type": "string"
                    },
                    {
                        "type": "null"
                    }
                    ],
                }
            }
        }
    }
}
// ...

anyOf with null under "responses"

JSON

// ...
"responses": {
    "200": {
        "description": "Successful response",
        "content": {
            "application/json": {
                "schema": {
                    "type": "object",
                    "properties": {
                        "age": {
                            "anyOf": [
                                {
                                    "type": "integer"
                                },
                                {
                                    "type": "null"
                                }
                            ]
                        }
                    }
                }
            }
        }
    }
}
// ...

Not Supported Schema

anyOf in array of objects and null

JSON

// ...
"responses": {
  "200": {
    "description": "Successful response",
    "content": {
      "application/json": {
        "schema": {
          "type": "array",
          "items": {
            "anyOf": [
              {
                "type": "object",
                "properties": {
                  "age": {
                    "anyOf": [
                      {
                        "type": "integer"
                      },
                      {
                        "type": "null"
                      }
                    ],
                    "example": 10
                  },
                  "name": {
                    "anyOf": [
                      {
                        "type": "string"
                      },
                      {
                        "type": "null"
                      }
                    ],
                    "example": "robot"
                  }
                }
              }
            ]
          }
        }
      }
    }
  }
}
// ...

---

oneOf

Supported Schema

JSON

// ...
"responses": {
  "200": {
    "description": "Successful response",
    "content": {
      "application/json": {
        "schema": {
          "oneOf": [
            {
              "$ref": "#/components/schemas/AlphaResponse"
            },
            {
              "$ref": "#/components/schemas/BetaResponse"
            }
          ]
        }
      }
    }
  }
}
// ...
"components": {
  "schemas": {
    "AlphaResponse": {
      "type": "object",
      "properties": {
        "statustext": {
          "type": "string"
        },
        "good": {
          "type": "boolean"
        }
      }
    },
    "BetaResponse": {
      "type": "object",
      "properties": {
        "numbervalue": {
          "type": "integer"
        }
      }
    }
  }
}
// ...

Not Supported Schema

Discriminator

JSON

// ...
"discriminator": {
  "propertyName": "event_type",
  "mapping": {
    "temperature_alert": "#/components/schemas/TemperatureEvent",
    "motion_detection": "#/components/schemas/MotionEvent",
    "battery_status": "#/components/schemas/BatteryEvent"
  }
},
"oneOf": [
  {
    "$ref": "#/components/schemas/TemperatureEvent"
  },
  {
    "$ref": "#/components/schemas/MotionEvent"
  },
  {
    "$ref": "#/components/schemas/BatteryEvent"
  }
]
// ...

---

Enumeration

Supported Schemas

JSON

// ...
"components": {
    "schemas": {
      "StatusEnum": {
        "enum": [
          "PROCESSING",
          "BULK_PROCESSING",
          "ERROR",
          "DONE"
        ],
        "title": "StatusEnum",
        "type": "string"
      }
  }
}
// ...