Self-describing data

Self-describing data carries type information along with the data. For example, the previous data might get encoded as

  1. table
  2.     uint8 3
  3.     uint 2
  4. string
  5.     uint8 4
  6.     []byte fred
  7. string
  8.     uint8 10 
  9.     []byte programmer
  10. string
  11.     uint8 6 
  12.     []byte liping
  13. string
  14.     uint8 7 
  15.     []byte analyst
  16. string
  17.     uint8 8 
  18.     []byte sureerat
  19. string
  20.     uint8 7
  21.     []byte manager

Of course, a real encoding would not normally be as cumbersome and verbose as in the example: small integers would be used as type markers and the whole data would be packed in as small a byte array as possible (XML provides a counter-example, though).
However, the principle is that the marshaller will generate such type information in the serialised data. The unmarshaller will know the type-generation rules and will be able to use this to reconstruct the correct data structure.