# Flow block in Amazon Connect: AWS Lambda function
<a name="invoke-lambda-function-block"></a>

This topic defines the flow block for calling AWS Lambda. The fetched response can be used in the [Set contact attributes](set-contact-attributes.md) block.

## Description
<a name="invoke-lambda-function-block-description"></a>
+ Calls AWS Lambda.
+ The returned data can be used to set contact attributes in the [Set contact attributes](set-contact-attributes.md) block.
+ For an example, see [Tutorial: Create a Lambda function and invoke in a flow](connect-lambda-functions.md#tutorial-invokelambda).

## Supported channels
<a name="invoke-lambda-channels"></a>

The following table lists how this block routes a contact who is using the specified channel. 


| Channel | Supported? | 
| --- | --- | 
| Voice | Yes | 
| Chat | Yes | 
| Task | Yes | 
| Email | Yes | 

## Flow types
<a name="invoke-lambda-function-block-types"></a>

You can use this block in the following [flow types](create-contact-flow.md#contact-flow-types):
+ Inbound flow
+ Customer Queue flow
+ Customer Hold flow
+ Customer Whisper flow
+ Agent Hold flow
+ Agent Whisper flow
+ Transfer to Agent flow 
+ Transfer to Queue flow

## Properties
<a name="invoke-lambda-function-block-properties"></a>

The following image shows the **Properties** page of the **AWS Lambda function** block.

![\[The properties page of the AWS Lambda function block.\]](http://docs.aws.amazon.com/connect/latest/adminguide/images/aws-lamdba-function-properties.png)


In the **Select an action** box, choose from the following options:
+ [Invoke Lambda](#properties-invoke-lamdba)
+ [Load Lambda result](#properties-load-lamdba) (if run asynchronously)

### Invoke Lambda
<a name="properties-invoke-lamdba"></a>

![\[The Select an action box set to Invoke Lambda, the Execution mode options.\]](http://docs.aws.amazon.com/connect/latest/adminguide/images/invoke-lambda-properties2.png)


When **Select an action** is set to **Invoke Lambda**, note the following properties: 
+ **Execution mode**:
  + **Synchronous**: When Synchronous is selected, the contact is routed to the next block only after the Lambda invocation completes.
  + **Asynchronous**: The contact is routed to the next block without waiting for the Lambda to complete.

    You can configure [Wait](wait.md) block to wait for a Lambda that is invoked using the asynchronous execution mode.
+ **Timeout**: Enter how long to wait for Lambda to time out. You can enter maximum of 8 seconds for **Synchronous mode** and 60 seconds for **Asynchronous mode**.

  If your Lambda invocation gets throttled, the request is retried. It is also retried if a general service failure (500 error) happens. 

  When a Lambda invocation returns an error, Amazon Connect retries up to three times, for maximum until timeout specified. At that point, the contact is routed down the **Error** branch.
+ **Response validation**: The Lambda function response may be either a STRING\$1MAP or JSON. You must set it when you configure the **AWS Lambda function** block in the flow. 
  + When the response validation is set to STRING\$1MAP, the Lambda function returns a flat object of key/value pairs of the string type.
  + When the response validation is set to JSON, the Lambda function returns any valid JSON including nested JSON.

### Load Lambda Result
<a name="properties-load-lamdba"></a>

![\[The Load Lambda Result action on the AWS Lambda Config tab.\]](http://docs.aws.amazon.com/connect/latest/adminguide/images/load-lambda-result.png)


When **Select an action** is set to **Load Lambda Result**, note the following properties: 
+ **Lambda Invocation RequestId**: This is the requestId of the Lambda when it is run in **Asynchronous mode**.

  `$.LambdaInvocation.InvocationId` contains the requestId of the most recent asynchronously run Lambda.

When you choose the **Load Lambda Result** action, choose the following options under **Lambda Invocation RequestId**:
+ **Namespace** = **Lambda Invocation**
+ **Key** = **Invocation ID**

## Configuration tips
<a name="invoke-lambda-function-block-tips"></a>
+ To use an AWS Lambda function in a flow, first add the function to your instance. For more information, see [Add a Lambda function to your Amazon Connect instance](connect-lambda-functions.md#add-lambda-function).
+ After you add the function to your instance, you can select the function from the **Select a function** drop-down list in the block to use it in the flow.

## Configured block
<a name="invoke-lambda-function-block-configured"></a>

The following image shows an example of what this block looks like when it is configured. It has two branches: **Success** and **Error**. It is configured for **Asynchronous** execution mode. When it's configured for **Synchronous** execution mode, it has a **Timeout** branch.

![\[A configured AWS Lambda function block.\]](http://docs.aws.amazon.com/connect/latest/adminguide/images/invoke-lambda-configured.png)


## Sample flows
<a name="invoke-lambda-function-block-samples"></a>

Amazon Connect includes a set of sample flows. For instructions that explain how to access the sample flows in the flow designer, see [Sample flows in Amazon Connect](contact-flow-samples.md). Following are topics that describe the sample flows which include this block.

[Sample Lambda integration flow in Amazon Connect](sample-lambda-integration.md)

## Scenarios
<a name="invoke-lambda-function-block-scenarios"></a>

See these topics for scenarios that use this block:
+ [Grant Amazon Connect access to your AWS Lambda functions](connect-lambda-functions.md)