On the Android Developers blog, Wouter van Oortmerssen writes:
Game developers, we've just released FlatBuffers, a C++ serialization library that allows you to read data without unpacking or allocating additional memory, as an open source project. [...] Use this library to store game data with less overhead than alternative solutions (e.g. Protocol Buffers or JSON).
The Java generated for FlatBuffers is ugly. For example, use the schema language to define an enum with flat buffers:
enum Color:byte { Red = 0, Green, Blue = 2 }
That yields generated Java that isn't an enum!
public class Color {
public static final byte Red = 0;
public static final byte Green = 1;
public static final byte Blue = 2;
};
Worse, the format is not memory-safe. On Hacker News, Wouter writes:
Most readers of binary file formats can be made to read memory outside the buffer by corrupting the data, and FlatBuffers is no different.
That said, an option to bounds-check every offset would be possible, at a certain cost. Might be a nice optional feature to have.
Skipping bounds checks is what caused the Heartbleed bug. It's possible the Google servers using FlatBuffers may suffer the same problem!
FlatBuffers isn't ready. I'm going to stick with JSON (via Gson) & protocol buffers (via Wire).