Handling multiple messages in Java

[Carlos Pereira]

Hi,

Currently I'm working with ProtoBuf at work. There's a client device that sends us messages using ProtoBuf, so we can't change the protocol. The first 3 bytes is the length of the ProtoBuf message with big endian bytes order and then after that is the message itself. However, the .proto file they sent us defines multiple types of messages.

I'm using a CodedInputStream to first read the length of the serialized message and then read this size.

My problem is that after having bytes of the message I don't know which class inside the protc generated file I should use to call the parseFrom.

Any idea?

Best Regards,

[Carlos Pereira]

I forgot to mention that the file they sent us is using Protocol Buffers 2.

BR,

[Adam Cozzette]

Serialized protocol buffers don't contain any metadata to indicate what type they are, so you have to have some other mechanism to know what the type is. I would guess that your .proto file probably has a parent message containing the other messages, and the parent is probably the one that is always sent.

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[Carlos Pereira]

You're absolutely right! Thanks!

BR

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Carlos Duarte Pereira