> ## Documentation Index > Fetch the complete documentation index at: https://docs.together.ai/llms.txt > Use this file to discover all available pages before exploring further. # Get forward-backward operation > Retrieves the current status and result of a forward-backward operation. ## OpenAPI ````yaml openapi.yaml GET /rl/training-sessions/{session_id}/operations/forward-backward/{operation_id} openapi: 3.1.0 info: title: Together APIs description: The Together REST API. See https://docs.together.ai for more details. version: 2.0.0 termsOfService: https://www.together.ai/terms-of-service contact: name: Together Support url: https://www.together.ai/contact license: name: MIT url: https://github.com/togethercomputer/openapi/blob/main/LICENSE servers: - url: https://api.together.ai/v1 description: Default environment for APIs - url: https://api-inference.together.ai/v2 description: Optimized environment for inference security: - bearerAuth: [] paths: /rl/training-sessions/{session_id}/operations/forward-backward/{operation_id}: get: tags: - RL summary: Get forward-backward operation description: Retrieves the current status and result of a forward-backward operation. operationId: getForwardBackwardOperation parameters: - name: session_id in: path required: true schema: description: Training session ID type: string - name: operation_id in: path required: true schema: description: Operation ID type: string responses: '200': description: Forward-backward operation details content: application/json: schema: $ref: '#/components/schemas/RL.ForwardBackwardOperation' default: description: An unexpected error response. content: application/json: schema: $ref: '#/components/schemas/ErrorData' components: schemas: RL.ForwardBackwardOperation: type: object description: Async forward-backward pass operation required: - id - status properties: id: type: string example: 550e8400-e29b-41d4-a716-446655440000 description: Operation ID status: $ref: '#/components/schemas/RL.TrainingOperationStatus' example: TRAINING_OPERATION_STATUS_PENDING description: Operation status output: $ref: '#/components/schemas/RL.ForwardBackwardResult' description: Result on success error: $ref: '#/components/schemas/RL.TrainingOperationError' description: Error details on failure ErrorData: type: object required: - error properties: error: type: object properties: message: type: string nullable: false type: type: string nullable: false param: type: string nullable: true default: null code: type: string nullable: true default: null required: - type - message RL.TrainingOperationStatus: type: string enum: - TRAINING_OPERATION_STATUS_UNSPECIFIED - TRAINING_OPERATION_STATUS_PENDING - TRAINING_OPERATION_STATUS_RUNNING - TRAINING_OPERATION_STATUS_COMPLETED - TRAINING_OPERATION_STATUS_FAILED default: TRAINING_OPERATION_STATUS_UNSPECIFIED RL.ForwardBackwardResult: type: object description: Result of a scored forward or forward-backward operation required: - loss properties: loss: type: number example: 2.345 description: Loss value metrics: type: object description: Loss-specific metrics (e.g., KL divergence, clip fraction for GRPO) example: loss/clip/high_fraction: 0.1 loss/kl_ref/mean: 0.05 additionalProperties: type: number loss_fn_outputs: type: array description: >- Per-sample loss function outputs, in request order. Empty unless the request set `return_loss_fn_outputs`. items: $ref: '#/components/schemas/RL.LossFnOutput' RL.TrainingOperationError: type: object description: Error details for a failed training operation properties: code: $ref: '#/components/schemas/RL.TrainingOperationErrorCode' description: Application error code example: TRAINING_OPERATION_ERROR_CODE_TIMEOUT message: description: Human-readable error message type: string example: Operation timed out RL.LossFnOutput: type: object description: Output tensors produced by the loss function for one sample. required: - tensors properties: tensors: type: object description: >- Output tensors keyed by name. Built-in losses return `logprobs`: the model's float32 per-token log-probabilities under the current policy, one value per token of the sample's input. Positions excluded from the loss, such as zero-weight positions, are masked to zero rather than true log-probabilities. additionalProperties: $ref: '#/components/schemas/RL.TensorData' RL.TrainingOperationErrorCode: type: string description: Application error code for a failed training operation enum: - TRAINING_OPERATION_ERROR_CODE_UNSPECIFIED - TRAINING_OPERATION_ERROR_CODE_RESOURCE_EXHAUSTED - TRAINING_OPERATION_ERROR_CODE_TIMEOUT - TRAINING_OPERATION_ERROR_CODE_INTERNAL_ERROR - TRAINING_OPERATION_ERROR_CODE_SESSION_NOT_ACTIVE - TRAINING_OPERATION_ERROR_CODE_INVALID_INPUT - TRAINING_OPERATION_ERROR_CODE_NON_FINITE_LOSS default: TRAINING_OPERATION_ERROR_CODE_UNSPECIFIED RL.TensorData: type: object description: A tensor encoded as flattened row-major values, with an optional shape. required: - data - dtype properties: data: type: array description: Flattened one-dimensional values encoded as JSON numbers. example: - 1 - 2 - 3 items: type: number format: double dtype: type: string enum: - int64 - float32 description: Tensor element type, either `int64` or `float32`. example: int64 shape: type: array description: >- Optional tensor shape; training operations accept one-dimensional tensors only, and the dimension must match the data length. example: - 3 items: type: integer sparse_crow_indices: type: array description: Unsupported for training operations. Omit this field. example: - 0 - 2 items: type: integer sparse_col_indices: type: array description: Unsupported for training operations. Omit this field. example: - 0 - 2 items: type: integer securitySchemes: bearerAuth: type: http scheme: bearer x-bearer-format: bearer x-default: default ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.