# HarnessMessageStartEvent
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Event indicating the start of a message.

## Contents
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 ** role **   <a name="BedrockAgentCore-Type-HarnessMessageStartEvent-role"></a>
The role of the message sender.  
Type: String  
Valid Values: `user | assistant`   
Required: Yes

## See Also
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For more information about using this API in one of the language-specific AWS SDKs, see the following:
+  [AWS SDK for C\$1\$1](https://docs.aws.amazon.com/goto/SdkForCpp/bedrock-agentcore-2024-02-28/HarnessMessageStartEvent) 
+  [AWS SDK for Java V2](https://docs.aws.amazon.com/goto/SdkForJavaV2/bedrock-agentcore-2024-02-28/HarnessMessageStartEvent) 
+  [AWS SDK for Ruby V3](https://docs.aws.amazon.com/goto/SdkForRubyV3/bedrock-agentcore-2024-02-28/HarnessMessageStartEvent)