Yep, as i wrote in my previous message, that was it.
Thanks for the feedback :)
mcdowella wrote:
> This is begining to sound like a well-known TCP gotcha. Like most
> stream protocols, there is nothing in the TCP protocol that marks the
> boundaries between sender write() calls; TCP sees the connection as a
> contiguous stream of bytes. If the protobuf message is fragmented into
> multiple tcp frames by the sender, read() calls on the receiver will
> typically be satisfied by the first tcp frame received. What is more,
> because the TCP implementation of write() can also stuff more than one
> write() call into an outgoing frame, the boundary between TCP frames
> is not easy to predict - you might get a split inside a small write()
> call because there was a little bit of space left over in a TCP frame
> from a previous call, but not enough for all of even a very small
> write(). It is therefore perfectly legal for you to call write() on
> {1,2} and for the receiver to get {1} as the response of a first call
> to read() and {2} as the response to the second call to read().
>
> If this causes a problem (as it typically does) it is up to you to
> e.g. prefix each chunk of data sent with a length count.
>
> A google search on TCP Message Boundary finds the following from "C#
> Network Programming"
>
> Because TCP does not preserve data message boundaries, you must
> compensate for that in your network programs. There are two ways to
> handle this:
>
> * Create a protocol that requires a one-for-one response to each data
> message sent from the host
> * Design a data message marker system to distinguish data message
> boundaries within the data stream
>
> (I'm not sure what their first option is, unless they mean that you
> denote the end of a data message by closing the TCP connection used to
> transfer it).
>
> On Oct 14, 12:01 pm, Dominik Steenken <[EMAIL PROTECTED]> wrote:
>
>> Yes, we are pretty sure that we do not modify the data prior to putting
>> it on the wire. We have discovered a new fact, however that will
>> hopefully shed some light on this bizarre error. The error seems to
>> occur the instance the protobuf message is fragmented in the transport
>> layer, i.e. when it is larger than a single tcp frame. Any thoughts on
>> that? Has someone encountered this error before?
>>
>> Kenton Varda wrote:
>>
>>> Are you sure that the data you are sending to the parser is exactly
>>> the same data that was generated by the serializer? Remember that
>>> protocol buffers are not self-delimiting, so you need to make sure
>>> that you limit the input to the exact number of bytes that were
>>> produced when serializing.
>>>
>>> If the data is exactly the same, then this is a bug. If you can
>>> create a small program or pair of programs that demonstrate the
>>> problem, I would be happy to debug it.
>>>
>>> On Mon, Oct 13, 2008 at 10:09 AM, Dominik Steenken <[EMAIL PROTECTED]
>>> <mailto:[EMAIL PROTECTED]>> wrote:
>>>
>>> Hi everyone,
>>>
>>> we are currrently implementing a server/client system, the server
>>> being implemented in c++, the client in java. During our last rounds
>>> of tests, we encountered a problem that had to do with the sending of
>>> (not so) long messages. on the (receiving) java side, we get the
>>> following exception:
>>> Exception in augnet.client.aim.connection.Receiver, Parse error:
>>> com.google.protobuf.InvalidProtocolBufferException: Protocol message
>>> contained an invalid tag (zero).
>>> com.google.protobuf.InvalidProtocolBufferException: Protocol message
>>> contained an invalid tag (zero).
>>> at
>>>
>>> com.google.protobuf.InvalidProtocolBufferException.invalidTag(InvalidProtocolBufferException.java:
>>> 52)
>>> at
>>> com.google.protobuf.CodedInputStream.readTag(CodedInputStream.java:
>>> 67)
>>> at com.google.protobuf.FieldSet.mergeFrom(FieldSet.java:397)
>>> at com.google.protobuf.AbstractMessage
>>> $Builder.mergeFrom(AbstractMessage.java:248)
>>> at com.google.protobuf.GeneratedMessage
>>> $Builder.mergeFrom(GeneratedMessage.java:1)
>>> at
>>> com.google.protobuf.CodedInputStream.readMessage(CodedInputStream.java:
>>> 227)
>>> at
>>> com.google.protobuf.FieldSet.mergeFieldFrom(FieldSet.java:482)
>>> at com.google.protobuf.FieldSet.mergeFrom(FieldSet.java:402)
>>> at com.google.protobuf.AbstractMessage
>>> $Builder.mergeFrom(AbstractMessage.java:248)
>>> at com.google.protobuf.GeneratedMessage
>>> $Builder.mergeFrom(GeneratedMessage.java:1)
>>> at
>>> com.google.protobuf.CodedInputStream.readMessage(CodedInputStream.java:
>>> 227)
>>> at
>>> com.google.protobuf.FieldSet.mergeFieldFrom(FieldSet.java:482)
>>> at com.google.protobuf.FieldSet.mergeFrom(FieldSet.java:402)
>>> at com.google.protobuf.AbstractMessage
>>> $Builder.mergeFrom(AbstractMessage.java:248)
>>> at com.google.protobuf.AbstractMessage
>>> $Builder.mergeFrom(AbstractMessage.java:240)
>>> at com.google.protobuf.AbstractMessage
>>> $Builder.mergeFrom(AbstractMessage.java:298)
>>> at augnet.client.aim.messages.MessageProtos
>>> $AugNetMessage.parseFrom(MessageProtos.java:6289)
>>> at augnet.client.aim.connection.Receiver.run(Receiver.java:47)
>>>
>>> while the (sending) c++ side encounters no errors. When we scale down
>>> the message, no error occurs. Is this a bug in protobuf or are we
>>> doing something wrong?
>>>
>>> Best regards,
>>> Dominik
>>>
> >
>
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