how to fetch the 3 level folder/subfolders items from sharepoint library and display onto infopath browser form

Hi All,

I have structure like below:

Document Library

   Parent Folder( Folder A, Folder B, Folder C... so on)

      SubFolder(SubFolder A, SubFolder B, SubFolder C.. so on)

          Sub- SubFolder(Sub- SubFolder A, Sub- SubFolder B, Sub- SubFolder C.. so on)

               Items in Sub-Sub Folder.... File1, File2, File3... so on

I need to match the values from infopath form for Parent folder, SubFolder, Sub- SubFolder and fetch the items from Sub-SubFolder and display on infopath form.

Now I can able to retrieve all the items irrespective to folder structure.

Please help me out to write the webservice, so that I can add secondary dataconnection for infopath.

Thank you