> ## Documentation Index > Fetch the complete documentation index at: https://docs.lerian.studio/llms.txt > Use this file to discover all available pages before exploring further. # Derive an Operation Schema > Use this endpoint to derive the input and output contract of a single operation in an external OpenAPI schema. The response carries the dereferenced request-body and 2xx response schemas, the input parameters merged by location, and the body descriptor. Identify the operation with the `path` query parameter, which is the URL-encoded OpenAPI path template, and the `method` query parameter, which is case-insensitive. ## OpenAPI ````yaml en/openapi/v3-current/flowker.yaml get /v1/openapi-schemas/{id}/operation-schema openapi: 3.1.0 info: description: >- Complete API reference for Flowker workflow orchestration services including catalog management, workflow definitions, executor configurations, provider configurations, and workflow executions. title: Flowker API version: 1.2.0 servers: - url: https://flowker.sandbox.lerian.net security: - BearerAuth: [] tags: - name: Catalog API description: >- Browse built-in providers, executors, and triggers available in the Flowker catalog. - name: Workflows API description: >- Create, update, activate, deactivate, clone, and delete workflow definitions. - name: Executions API description: Start workflow executions and track their status and results. - name: Executor Configurations API description: >- List, inspect, update, and delete the executor configuration records a deployment holds. - name: Provider Configurations API description: >- Create, update, enable, and disable the provider configurations that workflow nodes call through. - name: Dashboard API description: >- Retrieve aggregated summaries of workflows and executions for operational dashboards. - name: Webhooks API description: >- Receive webhook callbacks from external systems to trigger workflow executions. - name: Schedule API description: >- Inspect a workflow's upcoming, skipped, and parked scheduled occurrences, and run or discard the parked ones. - name: Schema Registry API description: >- Publish global OpenAPI specification versions for native services and pin the version each tenant resolves against. - name: OpenAPI Schemas API description: >- Upload, inspect, and delete the tenant's external OpenAPI schemas, and derive the contract of a single operation. - name: XSD Schemas API description: >- Upload, inspect, and delete the tenant's XSD schemas used to validate XML webhook payloads. paths: /v1/openapi-schemas/{id}/operation-schema: get: tags: - OpenAPI Schemas API summary: Derive an Operation Schema description: >- Use this endpoint to derive the input and output contract of a single operation in an external OpenAPI schema. The response carries the dereferenced request-body and 2xx response schemas, the input parameters merged by location, and the body descriptor. Identify the operation with the `path` query parameter, which is the URL-encoded OpenAPI path template, and the `method` query parameter, which is case-insensitive. operationId: deriveOpenAPIOperationSchema parameters: - description: OpenAPI Schema ID (UUID). in: path name: id required: true schema: description: OpenAPI Schema ID (UUID). type: string example: 018f3e2a-1c4d-7b9e-a1b2-c3d4e5f6a7b8 - description: OpenAPI operation path template (URL-encoded), e.g. /kyc/{caseId}. explode: false in: query name: path schema: description: OpenAPI operation path template (URL-encoded), e.g. /kyc/{caseId}. type: string example: /kyc/{caseId} - description: >- HTTP method (case-insensitive: GET, PUT, POST, DELETE, OPTIONS, HEAD, PATCH, TRACE). explode: false in: query name: method schema: description: >- HTTP method (case-insensitive: GET, PUT, POST, DELETE, OPTIONS, HEAD, PATCH, TRACE). type: string example: POST responses: '200': content: application/json: schema: $ref: '#/components/schemas/OperationContractOutput' description: >- Indicates that the request was successful and the response contains the requested data. default: content: application/problem+json: schema: $ref: '#/components/schemas/ErrorResponse' description: >- Indicates that the request failed. The body is an RFC 9457 problem document. components: schemas: OperationContractOutput: additionalProperties: false properties: bodyContentType: type: string example: application/json bodyRequired: type: boolean example: true found: type: boolean example: true hasBody: type: boolean example: true inputSchema: description: Dereferenced JSON Schema of the operation's request body. example: properties: amount: type: number type: object outputSchema: description: Dereferenced JSON Schema of the operation's 2xx response body. example: properties: id: type: string type: object params: items: $ref: '#/components/schemas/OperationParamOutput' type: - array - 'null' required: - found - params - hasBody - bodyRequired type: object ErrorResponse: properties: code: description: Stable, machine-readable Flowker error code. example: FLK-0001 type: string detail: description: >- Human-readable explanation of this occurrence. Responses with a status of 500 or above carry a fixed generic message. example: name is a required field type: string errors: description: Per-field entries for a request that failed validation. items: $ref: '#/components/schemas/ErrorDetail' type: array instance: description: URI reference identifying this specific occurrence. example: /v1/workflows format: uri type: string status: description: HTTP status code. example: 400 type: integer title: description: >- Standard HTTP reason phrase for the status. It does not change per error code. example: Bad Request type: string type: description: >- URI reference identifying the error. Always the error catalog base followed by the code. example: https://errors.lerian.studio/v1/FLK-0001 format: uri type: string type: object OperationParamOutput: additionalProperties: false properties: in: description: Parameter location (path, query, header, or cookie). type: string example: path name: description: Parameter name. type: string example: caseId required: description: Whether the parameter is required by the operation. type: boolean example: true schema: description: Dereferenced JSON Schema of the parameter value. example: type: string required: - name - in - required type: object ErrorDetail: properties: location: description: Where the problem is, such as body.nodes or path.id. example: body.nodes type: string message: description: Description of the field-level problem. example: expected array length >= 1 type: string value: description: The value that caused the error, when it is safe to echo. type: object securitySchemes: BearerAuth: type: http scheme: bearer bearerFormat: JWT description: >- JWT bearer token issued by the identity provider. Send it in the Authorization header as `Bearer `. ````