[MESOS-3562] Anomalous bytes in stream from HTTPI Api

• Type: Bug
• Status: Resolved
• Priority: Blocker
• Resolution: Won't Fix
• Affects Version/s: 0.24.0
• Component/s: HTTP API
• Labels: http mesosphere wireprotocol

Environment

Linux 3.16.7-24-desktop #1 SMP PREEMPT Mon Aug 3 14:37:06 UTC 2015 (ec183cc) x86_64 x86_64 GNU/Linux

Mesos 0.24.0
gcc (SUSE Linux) 4.8.3 20140627 [gcc-4_8-branch revision 212064]

• Assignee: Unassigned
• Reporter: Ben Whitehead
• Created: 30/Sep/15 21:37
• Updated: 16/Oct/15 13:50
• Resolved: 07/Oct/15 18:38

Description

When connecting to the new HTTP Api and attempting to SUBSCRIBE there are some anomalous bytes contained in the chunked stream that appear to be causing problems when I attempting to integrate.

Attached are two log files. app.log represents my application trying to connect to mesos using RxNetty. Netty has been configured to log all data it sends/receives over the wire this can be seen in the byte blocks in the log.

The client is constructing a protobuf in java for the subscribe call

        final Call subscribeCall = Call.newBuilder()
            .setType(Call.Type.SUBSCRIBE)
            .setSubscribe(
                Call.Subscribe.newBuilder()
                    .setFrameworkInfo(
                        Protos.FrameworkInfo.newBuilder()
                            .setUser("bill")
                            .setName("testing")
                            .build()
                    )
            )
            .build();

lient sends the protobuf to mesos with the following request headers:

POST /api/v1/scheduler HTTP/1.1
Content-Type: application/x-protobuf
Accept: application/json
Content-Length: 35
Host: localhost:5050
User-Agent: RxNetty Client

The body is then serialized via protobuf and sent.

The response from the mesos master has the following headers:

HTTP/1.1 200 OK
Transfer-Encoding: chunked
Date: Wed, 30 Sep 2015 21:07:16 GMT
Content-Type: application/json

followed by

\r\n\r\n6c\r\n104\n{"subscribed":{"framework_id":{"value":"20150930-103028-16777343-5050-11742-0028"}},"type":"SUBSCRIBED"}

The \r\n\r\n is expected for standard http bodies, how ever 6c\r\n doesn't appear to be attached to anything. 104 is the correct length of the Subscribe events JSON.

What is this extra number and why is it there?

This is not the first time confusion has come up related to the wire format for the event stream from the new http api see this message from the mailing list.

In the Design Doc there is a statement that said

All subsequent events that are relevant to this framework generated by Mesos are streamed on this connection. Master encodes each Event in RecordIO format, i.e., string representation of length of the event followed by JSON or binary Protobuf (possibly compressed) encoded event.

There is no specification I've been able to find online that actually explains this format. The only reference I can find to it is some sample go code.

The attached tcpdump.log contains a tcp dump between the mesos master and my client collected using the following command tcpdump -xx -n -i lo "dst port 5050" or "src port 5050" 2>&1 | tee /tmp/tcpdump.log

Issue Links

• is related to: MESOS-3601 Formalize all headers and metadata for HTTP API Event Stream
• relates to: MESOS-3566 Add a section to the Scheduler HTTP API docs around RecordIO specification