# EventParameters
<a name="API_EventParameters"></a>

 **[Event-based policies only]** Specifies an event that activates an event-based policy.

## Contents
<a name="API_EventParameters_Contents"></a>

 ** DescriptionRegex **   <a name="dlm-Type-EventParameters-DescriptionRegex"></a>
The snapshot description that can trigger the policy. The description pattern is specified using a regular expression. The policy runs only if a snapshot with a description that matches the specified pattern is shared with your account.  
For example, specifying `^.*Created for policy: policy-1234567890abcdef0.*$` configures the policy to run only if snapshots created by policy `policy-1234567890abcdef0` are shared with your account.  
Type: String  
Length Constraints: Minimum length of 0. Maximum length of 1000.  
Pattern: `[\p{all}]*`   
Required: Yes

 ** EventType **   <a name="dlm-Type-EventParameters-EventType"></a>
The type of event. Currently, only snapshot sharing events are supported.  
Type: String  
Valid Values: `shareSnapshot`   
Required: Yes

 ** SnapshotOwner **   <a name="dlm-Type-EventParameters-SnapshotOwner"></a>
The IDs of the Amazon Web Services accounts that can trigger policy by sharing snapshots with your account. The policy only runs if one of the specified Amazon Web Services accounts shares a snapshot with your account.  
Type: Array of strings  
Array Members: Minimum number of 0 items. Maximum number of 50 items.  
Length Constraints: Fixed length of 12.  
Pattern: `^[0-9]{12}$`   
Required: Yes

## See Also
<a name="API_EventParameters_SeeAlso"></a>

For more information about using this API in one of the language-specific Amazon SDKs, see the following:
+  [Amazon SDK for C\$1\$1](https://docs.amazonaws.cn/goto/SdkForCpp/dlm-2018-01-12/EventParameters) 
+  [Amazon SDK for Java V2](https://docs.amazonaws.cn/goto/SdkForJavaV2/dlm-2018-01-12/EventParameters) 
+  [Amazon SDK for Ruby V3](https://docs.amazonaws.cn/goto/SdkForRubyV3/dlm-2018-01-12/EventParameters)