How to set file name from attachment data (payload swap bean)

Hi Experts,

I have a scenario from SOAP proxy to SFTP with attchment. I have used payloadswapbean to consider attachment as main payload.

I can able to successfully send the attachment to Target system. Where as my requirement is,  I need to set file name by using  2 fields of data(Country code and payment type)  from that attachment.

There is no mapping involved in this. Proxy will trigger only sample data(I wont use this data at all) but attachment is the actual content which I will send to client.

As per my knowledge we can use UDF to set dynamic file name, but I don't know how can I apply in my scenario.

Please suggest me on this.

Thanks,

Gayathri.