"files_from_ftp":
{
   "file1":
   {
      "full_name":"very-long-file-name-1"
      "url":"ftp://.....very-long-file-name-1.zip"
   },
   "file2":
   {
      "full_name":"very-long-file-name-2"
      "url":"ftp://.....very-long-file-name-2.zip"
   }
},
"files_from_network":
{
  "file3":
  {
     "full_name":"very-long-file-name-3"
     "network_path":"file:///SOMEWHERE/ON/THE/NETWORK/very-long-file-name.zip"
  }
},
"files_from_s3":
{
  "file4":
  {
     "full_name":"very-long-file-name-4"
     "url":"s3://some.s3.bucket/very-long-file-name-4.tar"
  }
}

- name: process files from ftp
  shell: some_command -f /home/ubuntu/downloaded_files/{{ item.value.full_name }}
  with_dict: files_from_ftp | default({})

- name: process files from network
  shell: some_command -f /home/ubuntu/downloaded_files/{{ item.value.full_name }}
  with_dict: files_from_network | default({})

- name: process files from s3
  shell: some_command -f /home/ubuntu/downloaded_files/{{ item.value.full_name }}
  with_dict: files_from_s3 | default({})

- name: process all downloaded files
  shell: some_command -f /home/ubuntu/downloaded_files/{{ item.value.full_name }}
  with_dict: ( files_from_s3 | default({}) )
             and ( files_from_ftp | default({}) )
             and ( files_from_network | default({}) )