On 1/30/13 4:17 PM, Jay Kreps wrote:
Ah, yes, the decision since we were making a breaking change to the
protocol to just reset all the versions to 0.
Excellent, I shall purge my 0.7x compatible code at once :)
But if you are trying to
handle both cases from the same code that will be hard.

-Jay


On Wed, Jan 30, 2013 at 12:59 PM, David Arthur <mum...@gmail.com> wrote:

Jay,

Figured it out.

In Message.scala, CurrentMagicValue is set to 0; should be 2. This was
causing my client to attempt to decode it as a v0 message. Changing the
value to 2 solved my problem. Seems like a trivial change, so I'll let you
decided if you want a Jira or not.

 From my previous example, https://gist.github.com/**
bf134906f6559b0f54ad#file-**gistfile1-txt-L71<https://gist.github.com/bf134906f6559b0f54ad#file-gistfile1-txt-L71>should
 be 2

-David

messages to set their offsets

On 1/30/13 11:18 AM, Jay Kreps wrote:

Hi David,

MessageSets aren't size delimited because that format is shared with
producer/consumer and the kafka log itself. The log itself is just a big
sequence of messages and any subset that begins and ends at valid message
boundaries is a valid message set. This means that message sets are size
prefixed only as part of the request/response. Not sure if that is what
you
are asking?

It's hard to see the cause of the error you describe. I don't suppose you
could send me a snapshot of your client to reproduce locally?

-Jay




On Wed, Jan 30, 2013 at 7:26 AM, David Arthur <mum...@gmail.com> wrote:

  I'm working on a client and I'm running into difficulties with compressed
message sets. I am able to produce them fine, but when I go to fetch
them,
things seem strange.

I am sending a message who's value is a compressed message set. The inner
message set contains a single message. Specifically what looks weird is
that the key of the top message looks corrupt. Here is a trace of my
payloads:

https://gist.github.com/****bf134906f6559b0f54ad<https://gist.github.com/**bf134906f6559b0f54ad>
<https://**gist.github.com/**bf134906f6559b0f54ad<https://gist.github.com/bf134906f6559b0f54ad>

See the "???" down in the FetchResponse for what I mean. Also the magic
byte and attributes are wrong

The data in the Kafka log for this partition matches what I get back for
the MessageSet in the FetchResponse:

\x00\x00\x00\x00\x00\x00\x00\****x00\x00\x00\x00;\xf5#\xc2N\**
x00\x01\xff\xff\xff\xff\x00\****x00\x00-\x1f\x8b\x08\x00\x00\****
x00\x00\x00\x00\x00c`\x80\x03\****x89P\xf7\xef\xccL
\x16sZ~>\x90bw\x8f\xf2\x0c\****x08HM\x01\x00\xc5\x93\xd3<$\****
x00\x00\x00


Another bit of weirdness here is how MessageSets are encoded. Everywhere
else in the API, we prefix a repeated element with a size of int32. When
encoding MessageSets, if I follow this convention, Kafka rejects the
produce request - if I exclude that int32 it works fine. I don't know if
this was intentional or not, but it is somewhat annoying and
inconsistent.
When decoding MessageSets, I have to do-while instead of iterate a known
number of times.

Cheers
-David



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