Physical inventory

Hi,

I want to know how the below requirement is to be handled?

inventory is managed by 3rd party logistics(non SAP), whenever we create Inventory record(cycle count / annual) in SAP system, the necessary information is to be sent to 3PL system(IDOC) and they start the actual counting process. These counted results are to be updated in SAP system so that the differences can be posted in SAP.

here i would like to know how this can be handled? at what stage the Idoc need to be triggereed and also the information on Basic type, message types and the segment types which can be used.

any sort of help would be appreciated.

Thanks.