A single sign-on is implemented in an online transaction processing system. A security token extracted from a transaction request is received. The security token is validated and, in response to a positive validation, security information is extracted. The security information is processed to validate the transaction request and a set of validation attributes is generated. The set of validation attributes is stored in a read-only data object. A transaction server is notified of the read-only data object to authorize processing of the transaction request by the transaction server.