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From Vinod Kone <vinodk...@apache.org>
Subject Re: [VOTE] Release Apache Mesos 0.24.0 (rc1)
Date Fri, 28 Aug 2015 16:13:09 GMT
I'm happy to add the "\n" after the event (note it's different from chunk)
if that makes CURL play nicer. I'm not sure about the "\r" part though? Is
that a nice to have or does it have some other benefit?

The design doc is not set in the stone since this has not been released
yet. So definitely want to do the right/easy thing.

On Fri, Aug 28, 2015 at 7:53 AM, Anand Mazumdar <anand@mesosphere.io> wrote:

> Dario,
>
> Thanks for the detailed explanation and for trying out the new API.
> However, this is not a bug. The output from CURL is the encoding used by
> Mesos for the events stream. From the user doc
> <https://github.com/apache/mesos/blob/master/docs/scheduler_http_api.md>:
>
> *"Master encodes each Event in RecordIO format, i.e., string
> representation of length of the event in bytes followed by JSON or binary
> Protobuf  (possibly compressed) encoded event. Note that the value of
> length will never be ‘0’ and the size of the length will be the size of
> unsigned integer (i.e., 64 bits). Also, note that the RecordIO encoding
> should be decoded by the scheduler whereas the underlying HTTP chunked
> encoding is typically invisible at the application (scheduler) layer.“*
>
> If you run CURL with tracing enabled i.e. —trace, the output would be
> something similar to this:
>
> <= Recv header, 2 bytes (0x2)
> 0000: 0d 0a                                           ..
> <= Recv data, 115 bytes (0x73)
> 0000: 36 64 0d 0a 31 30 35 0a 7b 22 73 75 62 73 63 72 6d..105.{"subscr
> 0010: 69 62 65 64 22 3a 7b 22 66 72 61 6d 65 77 6f 72 ibed":{"framewor
> 0020: 6b 5f 69 64 22 3a 7b 22 76 61 6c 75 65 22 3a 22 k_id":{"value":"
> 0030: 32 30 31 35 30 38 32 35 2d 31 30 33 30 31 38 2d 20150825-103018-
> 0040: 33 38 36 33 38 37 31 34 39 38 2d 35 30 35 30 2d 3863871498-5050-
> 0050: 31 31 38 35 2d 30 30 31 30 22 7d 7d 2c 22 74 79 1185-0010"}},"ty
> 0060: 70 65 22 3a 22 53 55 42 53 43 52 49 42 45 44 22 pe":"SUBSCRIBED"
> 0070: 7d 0d 0a                                        }..
> <others
>
> In the output above, the chunks are correctly delimited by ‘CRLF' (0d 0a)
> as per the HTTP RFC. As mentioned earlier, the output that you observe on
> stdout with CURL is of the Record-IO encoding used for the events stream (
> and is not related to the RFC ):
>
> event = event-size LF
>              event-data
>
> Looking forward to more bug reports as you try out the new API !
>
> -anand
>
> On Aug 28, 2015, at 12:56 AM, Dario Rexin <dario.rexin@me.com> wrote:
>
> -1 (non-binding)
>
> I found a breaking bug in the new HTTP API. The messages do not conform to
> the HTTP standard for chunked transfer encoding. in RFC 2616 Sec. 3 (
> http://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html) a chunk is defined
> as:
>
> chunk = chunk-size [ chunk-extension ] CRLF
>         chunk-data CRLF
>
>
> The HTTP API currently sends a chunk as:
>
> chunk = chunk-size LF
>         chunk-data
>
>
> A standard conform HTTP client like curl can’t correctly interpret the
> data as a complete chunk. In curl it currently looks like this:
>
> 104
>
> {"subscribed":{"framework_id":{"value":"20150820-114552-16777343-5050-43704-0000"}},"type":"SUBSCRIBED"}20
> {"type":"HEARTBEAT”}666
> …. waiting …
>
> {"offers":{"offers":[{"agent_id":{"value":"20150820-114552-16777343-5050-43704-S0"},"framework_id":{"value":"20150820-114552-16777343-5050-43704-0000"},"hostname":"localhost","id":{"value":"20150820-114552-16777343-5050-43704-O0"},"resources":[{"name":"cpus","role":"*","scalar":{"value":8},"type":"SCALAR"},{"name":"mem","role":"*","scalar":{"value":15360},"type":"SCALAR"},{"name":"disk","role":"*","scalar":{"value":2965448},"type":"SCALAR"},{"name":"ports","ranges":{"range":[{"begin":31000,"end":32000}]},"role":"*","type":"RANGES"}],"url":{"address":{"hostname":"localhost","ip":"127.0.0.1","port":5051},"path":"\/slave(1)","scheme":"http"}}]},"type":"OFFERS”}20
> … waiting …
> {"type":"HEARTBEAT”}20
> … waiting …
>
> It will receive a couple of messages after successful registration with
> the master and the last thing printed is a number (in this case 666). Then
> after some time it will print the first offers message followed by the
> number 20. The explanation for this behavior is, that curl can’t interpret
> the data it gets from Mesos as a complete chunk and waits for the missing
> data. So it prints what it thinks is a chunk (a message followed by the
> size of the next messsage) and keeps the rest of the message until another
> message arrives and so on. The fix for this is to terminate both lines, the
> message size and the message data, with CRLF.
>
> Cheers,
> Dario
>
>
>

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