# Processing Level 1: Getting the data in a standarized way.

A DocumentBuilder implementation is used for the layouting. There must be at least two implementations. The very simple one is holding the whole document in memory.

A more sophisticated one, which removes the fully processed nodes from the document allows the processing of larger documents, which would not fully fit into the available memory otherwise. That document-builder should be able to restart the processing from a certain page later.

An optional third one might accept already computed content as input, and therefore reduces the costs for the layouting without having to restart the whole input processing again.

Once sufficient document content is available, start the layouting.