# Orchest SDK¶

Note

💡 The Orchest SDK comes pre-installed when using Orchest.

## Python¶

### Data passing¶

Please refer to the dedicated section on .

### Parameters¶

Check out an example in the .

## R¶

Tip

👉 Import the example project showcasing R straight in Orchest ().

The Orchest SDK in R works through the reticulate package. To explain its usage, an example project is provided below.

First, create an Orchest environment which uses the orchest/base-kernel-r base image (you can find more details ). Next you want to install reticulate and configure access to Python and the Orchest SDK. You can do so by having a script (let’s say Install.r) in your project with the following content:

install.packages("reticulate", repos = "http://cran.us.r-project.org")
library(reticulate)

# Dynamically find system Python
python_path <- system("which python", intern=TRUE)
use_python(python_path)

# Pre compile orchest deps
orchest <- import("orchest")

print(orchest)


and having the environment set-up script perform Rscript Install.r. You will then be able to access the Orchest SDK through R in every step that makes use of this environment . To do data passing, for example, you would do the following:

library(reticulate);
python_path <- system("which python", intern=TRUE);
use_python(python_path);
orchest <- import("orchest");
orchest$transfer$output(2, name="Test");


In a child step you will be able to retrieve the output:

library(reticulate);
python_path <- system("which python", intern=TRUE);
use_python(python_path);
orchest <- import("orchest")
step_inputs = orchest$transfer$get_inputs()
step_inputs\$Test


## Julia¶

Refer to the Julia example project showcasing Julia in Orchest ().

## JavaScript¶

Refer to the JavaScript example project showcasing JavaScript in Orchest ().

## API reference¶

### orchest.transfer¶

Transfer mechanisms to output data and get data.

class orchest.transfer.Serialization(value)

Possible types of serialization.

Types are:

• ARROW_TABLE

• ARROW_BATCH

• PICKLE

orchest.transfer.get_inputs(ignore_failure: bool = False, verbose: bool = False) Dict[str, Any]

Gets all data sent from incoming steps.

Warning

Only call get_inputs() once! When auto eviction is configured data might no longer be available. Either cache the data or maintain a copy yourself.

Parameters
• ignore_failure – If True then the returned result can have None values if the data of a step could not be retrieved. If False, then this function will fail if any of the incoming steps’s data could not be retrieved. Example: [None, "Hello World!"] vs OutputNotFoundError

• verbose – If True print all the steps from which the current step has retrieved data.

Returns

Dictionary with input data for this step. We differentiate between two cases:

• Named data, which is data that was outputted with a name by any parent step. Named data can be retrieved through the dictionary by its name, e.g. data = get_inputs()["my_name"]. Name collisions will raise an InputNameCollisionError.

• Unnamed data, which is an ordered list containing all the data that was outputted without a name by the parent steps. Unnamed data can be retrieved by accessing the reserved "unnamed" key. The order of this list depends on the order of the parent steps of the node, which is visible through the GUI, refer to the for more details.

Example:

# It does not matter how the data was outputted by parent
# steps. It is resolved automatically by the get_inputs
# method.
{
"unnamed" : ["Hello World!", (3, 4)],
"named_1" : "mystring",
"named_2" : [1, 2, 3]
}


Raises
• InputNameCollisionError – Multiple steps have outputted data with the same name.

• OutputNotFoundError – If no output can be found of the given step_uuid. Either no output was generated or the in-memory object store died (and therefore lost all its data).

• StepUUIDResolveError – The step’s UUID cannot be resolved and thus it cannot determine what inputs to get.

orchest.transfer.output(data: Any, name: Optional[str]) None

Outputs data so that it can be retrieved by the next step.

Note

Calling output() multiple times within the same step will overwrite the output, even when using a different output name. You therefore want to be only calling the function once.

Parameters
• data – Data to output.

• name – Name of the output data. As a string, it becomes the name of the data, when None, the data is considered nameless. This affects the way the data can be later retrieved using get_inputs().

Raises
• DataInvalidNameError – The name of the output data is invalid, e.g because it is a reserved name ("unnamed") or because it contains a reserved substring.

• OrchestNetworkError – Could not connect to the Config.STORE_SOCKET_NAME, because it does not exist. Which might be because the specified value was wrong or the store died.

• StepUUIDResolveError – The step’s UUID cannot be resolved and thus data cannot be outputted.

Example

>>> data = "Data I would like to use in my next step"
>>> output(data, name="my_data")

orchest.transfer.output_to_disk(data: Any, name: Optional[str], serialization: Optional[Serialization] = None) None

Outputs data to disk.

Note

Calling output_to_disk() multiple times within the same script will overwrite the output, even when using a different output name. You therefore want to be only calling the function once.

To manage outputing the data to disk, this function has a side effect:

• Writes to a HEAD file alongside the actual data file. This file serves as a protocol that returns the timestamp of the latest write to disk via this function alongside the used serialization.

Parameters
• data – Data to output to disk.

• name – Name of the output data. As a string, it becomes the name of the data, when None, the data is considered nameless. This affects the way the data can be later retrieved using get_inputs().

• serialization – Serialization of the data in case it is already serialized. For possible values see Serialization.

Raises
• DataInvalidNameError – The name of the output data is invalid, e.g because it is a reserved name ("unnamed") or because it contains a reserved substring.

• PipelineDefinitionNotFoundError – If the pipeline definition file could not be found.

• StepUUIDResolveError – The step’s UUID cannot be resolved and thus it cannot determine where to output data to.

Example

>>> data = "Data I would like to use in my next step"
>>> output_to_disk(data, name="my_data")


### orchest.parameters¶

Module to interact with the parameter values of pipeline steps.

Handle to parameters that are stored in the corresponding pipeline definition file, e.g. pipeline.orchest.

orchest.parameters.get_params() Tuple[dict, dict]

Gets the parameters of the current step and the pipeline.

Returns

A tuple of two elements, where the first is the parameters of the current step, the second is the parameters of the pipeline.

orchest.parameters.get_pipeline_param(name: str, default: Optional[Any] = None) Any

Gets a pipeline parameter by name.

Parameters

name – The pipeline parameter to get.

Returns

The value that was mapped to the pipeline parameter name.

orchest.parameters.get_step_param(name: str, default: Optional[Any] = None) Any

Gets a parameter of the current step by name.

Parameters

name – The step parameter to get.

Returns

The value that was mapped to the step parameter name.

### orchest.services¶

Module to retrieve information about services.

Service specifications are stored in the corresponding pipeline definition file e.g. pipeline.orchest.

orchest.services.get_service(name) Dict[str, Any]

Gets the service of the pipeline by name.

Returns

A dictionary describing a service.

Example:

{
"internal_url": service-<service-name>-<identifier>,
"external_urls": {
80: "http://{host_name}:{port}/service"
"-<service-name>-<identifier>_80"
}
"base_paths": {
80: "/service-<service-name>-<identifier>_80"
}
... # user specified service fields
}


where each port specified in the service specification constitutes to one element in the external_urls and base_paths mappings, that map port to external urls and ports to base paths respectively.

Raises

ServiceNotFoundError – The service given by name name could not be found.

orchest.services.get_services() Dict[str, Dict[str, Any]]

Gets the services of the pipeline.

Returns

A dictionary of services, mapping service name to service description. For an example of a service dictionary, see get_service().