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javaprotocol-buffersprotostuff

Type of object in byte[] to deserialize with schema?

I'm trying to replace my string based protocol with one that uses protobuf. I serialize move command with:

Schema<MoveCommand> schema = RuntimeSchema.getSchema(MoveCommand.class);
ProtostuffIOUtil.toByteArray(this, schema, buffer)

And my hit command with:

Schema<Hitcommand> schema = RuntimeSchema.getSchema(Hitcommand.class);
ProtostuffIOUtil.toByteArray(this, schema, buffer)

This works without problems. When i serialize the result is a byte[], this data is send over and socket to a serversocket.

On the serverside i read out the byte[] array, but how can i determine the type of the object that is inside the byte[] array? (is it and HitCommand or a MoveCommand?)

I ask this because to deserialize i need a Schema and i can only create/get the schema when i know the class of the object that is inside the byte[] array.

With my old string protocol i just had the type of the message at the beginning of the string.

I suspect i'm missing something crucial.

Solution

  • The type of the message is not part of the serialized data. If you have no other way of specifying it, then you could create another message (maybe called Envelope) that holds either a Hitcommand or a MoveCommand. You could then always deserialize the envelope and see if Hitcommand or MoveCommand is defined.