# Processing input and output in Step Functions
<a name="concepts-input-output-filtering"></a>

**Managing state with variables and JSONata**  
Step Functions recently added variables and JSONata to manage state and transform data.  
Learn more in the blog post [Simplifying developer experience with variables and JSONata in AWS Step Functions](https://aws.amazon.com/blogs/compute/simplifying-developer-experience-with-variables-and-jsonata-in-aws-step-functions/) 

When a Step Functions execution receives JSON input, it passes that data to the first state in the workflow as input.

With JSONata, you can retrieve state input from `$states.input`. Your state machine executions also provide that initial input data in the [Context object](input-output-contextobject.md). You can retrieve the original state machine input at any point in your workflow from `$states.context.Execution.Input`.

 When states exit, their output is available to the *very* next state in your state machine. Your state inputs will pass through as state output by default, unless you **modify** the state output. For data that you might need in later steps, consider storing it in variables. For more info, see [Passing data between states with variables](workflow-variables.md). 

**QueryLanguage recommendation**  
For new state machines, we recommend the JSONata query language. In state machines that do not specify a query language, the state machine defaults to JSONPath for backward compatibility. You must opt-in to use JSONata for your state machines or individual states.

**Processing input and output with JSONata**

With JSONata expressions, you can select and transform data. In the `Arguments` field, you can customize the data sent to the action. The result can be transformed into custom state output in the `Output` field. You can also store data in variables in the `Assign` field. For more info, see [Transforming data with JSONata](transforming-data.md).

The following diagram shows how JSON information moves through a JSONata task state.

![\[Diagram showing JSONata task state flow with input, arguments, output, and action components.\]](http://docs.aws.amazon.com/step-functions/latest/dg/images/vars-jsonata.png)


**Processing input and output with JSONPath**

**Managing state and transforming data**  
Learn about [Passing data between states with variables](workflow-variables.md) and [Transforming data with JSONata](transforming-data.md).

For state machines that use JSONPath, the following fields control the flow of data from state to state: `InputPath`, `Parameters`, `ResultSelector`, `ResultPath`, and `OutputPath`. Each JSONPath field can manipulate JSON as it moves through each state in your workflow.

JSONPath fields can use [paths](amazon-states-language-paths.md) to select portions of the JSON from the input or the result. A path is a string, beginning with `$`, that identifies nodes within JSON text. Step Functions paths use [JsonPath](https://datatracker.ietf.org/wg/jsonpath/about/) syntax.

The following diagram shows how JSON information moves through a JSONPath task state. The `InputPath` selects the parts of the JSON input to pass to the task of the `Task` state (for example, an AWS Lambda function). You can adjust the data that is sent to your action in the `Parameters` field. Then, with `ResultSelector`, you can select portions of the action result to carry forward. `ResultPath` then selects the combination of state input and task results to pass to the output. `OutputPath` can filter the JSON output to further limit the information that's passed to the output.

![\[Order of filters: InputPath, Parameters, ResultSelector, ResultPath, and OutputPath.\]](http://docs.aws.amazon.com/step-functions/latest/dg/images/vars-jsonpath.png)


**Topics**
+ [Passing data between states with variables](workflow-variables.md)
+ [Transforming data with JSONata in Step Functions](transforming-data.md)
+ [Accessing execution data from the Context object in Step Functions](input-output-contextobject.md)
+ [Using JSONPath paths](amazon-states-language-paths.md)
+ [Manipulate parameters in Step Functions workflows](input-output-inputpath-params.md)
+ [Example: Manipulating state data with paths in Step Functions workflows](input-output-example.md)
+ [Specifying state output using ResultPath in Step Functions](input-output-resultpath.md)
+ [Map state input and output fields in Step Functions](input-output-fields-dist-map.md)