Essentially, once it is setup, it will run on a fully automated, scheduled basis, for any MIS data changes that are relevant to ParentPay and part of the current ParentPay upload set. Schedule can be set on a school by school basis (daily/nightly, weekly etc).
A local application talks to ParentPay and to the MIS, much the same as MIS:Sync does today. Main difference is allowing the full automation and scheduling for non-SIMS schools.
First release will work on full uploads (as per the current upload process), whereby all data is uploaded and then only the differences imported. A future release, probably later in the Autumn term, will allow either full or delta uploads. delta uploads do the 'differencing' locally and then only upload and import the changes (this just makes for a slightly lower bandwidth usage).
Uploads can always be over-ridden, should the school want to 'force' an upload at a specific time.