How to serialize a graph structure?

Question

Flat files and relational databases give us a mechanism to serialize structured data. XML is superb for serializing un-structured tree-like data.

But many problems are b

Answer 1

One example you might be familiar is Java serialization. This effectively serializes by graph, with each object instance being a node, and each reference being an edge. The algorithm used is recursive, but skipping duplicates. So the pseudo code would be:

serialize(x):
    done - a set of serialized objects
    if(serialized(x, done)) then return
    otherwise:
         record properties of x
         record x as serialized in done
         for each neighbour/child of x: serialize(child)

Another way of course is as a list of nodes and edges, which can be done as XML, or in any other preferred serialization format, or as an adjacency matrix.