This topic explains the architecture of a user store manager and it's main components. Once you have understood the concepts defined in this topic, you will be able to write a custom user store manager.
User store manager architecture
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In WSO2 Identity Server, the Claim Manager is responsible for adding/deleting claims and mapping claims from one namespace to another. The default implementation is DefaultClaimManager, which is used to store claim data in tables of the JDBC database.