On 02/14/2013 10:58 AM, Steven Hardy wrote:
On Wed, Feb 13, 2013 at 05:38:46PM +0000, Gordon Sim wrote:
On 02/13/2013 08:49 AM, Steven Hardy wrote:
Hi,
I'm trying to understand some differences encoding map datatypes between
qpid and rabbitmq (openstack project which needs to support both)
It seems that we hit a limit of 2^16 bytes when encoding a map on qpid,
because the map appears to be encoded as a string (write_map in codec010.py)
Looking at the amqp 0-10 spec, it says "An encoded map may contain up to
(4294967295 - 4) octets worth of encoded entries.", so I'm trying to
understand the 65535 byte limitation I'm hitting, since we do not appear to
hit the same problem when configured to use rabbit.
Can anyone please advise - is this a bug in python-qpid, or an expected
limitation of the qpid implementation?
I think that is a bug in python-qpid. Do you have a simple
reproducer you could attach to a JIRA?
JIRA raised with reproducer :
https://issues.apache.org/jira/browse/QPID-4583
It turns out you can encode larger values as binary by calling
'buffer()' on them. E.g. with the attached patch applied to your
reproducer the message gets sent and received without error.
My view is therefore that this is not a bug, since it is indeed true
that a string larger than 2^16 cannot be encoded as a str16, and there
is a reasonable simple way to indicate that the value should be treated
as binary which can then be encoded as vbin32.
Do you agree?
diff -up ./reproducer.py.orig ./reproducer.py
--- ./reproducer.py.orig 2013-02-15 14:00:28.294263872 +0000
+++ ./reproducer.py 2013-02-15 14:01:11.833266232 +0000
@@ -17,11 +17,15 @@ a_map = json.loads(a_template)
# If any key is > 2^16 bytes, str16 encoding fails
for key in a_map:
print "SHDEBUG len(str(a_map[%s])) = %s" % (key, len(str(a_map[key])))
+ if len(str(a_map[key])) > 65534:
+ a_map[key] = buffer(a_map[key])
+ print "encoding value of length %s as binary for key %s" % (len(str(a_map[key])), key)
print "SHDEBUG created a_map, type=%s" % type(a_map)
sender.send(Message(content=a_map))
message = receiver.fetch(timeout=1)
+print message.content
session.acknowledge()
connection.close()
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