I believe you can use WSO2 Data Services Server (DSS) or your requirement.
You can download WSO2 DSS from http://wso2.com/products/data-services-server/
It has support for Oracle RefCursor.
You can then use the data service via WSO2 ESB.
Following article might help.
http://wso2.com/library/tutorials/use-oracle-ref-cursors-wso2-data-services-server