Dario, Most HTTP libraries/parsers ( including one that Mesos uses internally ) provide a way to specify a default size of each chunk. If a Mesos Event is too big , it would get split into smaller chunks and vice-versa.
-anand > On Aug 28, 2015, at 11:51 AM, dario.re...@me.com wrote: > > Anand, > > in the example from my first mail you can see that curl prints the size of a > message and then waits for the next message and only when it receives that > message it will print the prior message plus the size of the next message, > but not the actual message. > > What's the benefit of encoding multiple messages in a single chunk? You could > simply create a single chunk per event. > > Cheers, > Dario > > On 28.08.2015, at 19:43, Anand Mazumdar <an...@mesosphere.io > <mailto:an...@mesosphere.io>> wrote: > >> Dario, >> >> Can you shed a bit more light on what you still find puzzling about the CURL >> behavior after my explanation ? >> >> PS: A single HTTP chunk can have 0 or more Mesos (Scheduler API) Events. So >> in your example, the first chunk had complete information about the first >> “event”, followed by partial information about the subsequent event from >> another chunk. >> >> As for the benefit of using RecordIO format here, how else do you think we >> could have de-marcated two events in the response ? >> >> -anand >> >> >>> On Aug 28, 2015, at 10:01 AM, dario.re...@me.com >>> <mailto:dario.re...@me.com> wrote: >>> >>> Anand, >>> >>> thanks for the explanation. I'm still a little puzzled why curl behaves so >>> strange. I will check how other client behave as soon as I have a chance. >>> >>> Vinod, >>> >>> what exactly is the benefit of using recordio here? Doesn't it make the >>> content-type somewhat wrong? If I send 'Accept: application/json' and >>> receive 'Content-Type: application/json', I actually expect to receive only >>> json in the message. >>> >>> Thanks, >>> Dario >>> >>> On 28.08.2015, at 18:13, Vinod Kone <vinodk...@apache.org >>> <mailto:vinodk...@apache.org>> wrote: >>> >>>> 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 <an...@mesosphere.io >>>> <mailto:an...@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.re...@me.com >>>>> <mailto:dario.re...@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 >>>>> <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 >>>> >>>> >>
