How to append content to a file while using file adapter in bpel

Modify the fileadapter wsdl with append="true" in the jca tag.
This will append the messages comes into the file.

jca:operation
LogicalDirectory="oc4j_soa"
InteractionSpec="oracle.tip.adapter.file.outbound.FileInteractionSpec"
FileNamingConvention="arrow_SW_IN_ORDER_CONTROLLER_OC4J_soa.log"
OpaqueSchema="false"
Append="true"