Put/Get serializable objects

[k4nar]

Both py-elevator and Elevator are using msgpack. One great thing about msgpack is that it allows fast and safe serialization of standard types. For example :

>>> import msgpack
>>> msgpack.dumps(42)
'*'
>>> msgpack.loads(_)
42
>>> msgpack.dumps([{'foo': ('bar', 1), 'bar': 42}, 'toto'])
'\x92\x82\xa3foo\x92\xa3bar\x01\xa3bar*\xa4toto'
>>> msgpack.loads(_)
[{'foo': ['bar', 1], 'bar': 42}, 'toto']
>>> _[0]
{'foo': ['bar', 1], 'bar': 42}

However, py-elevator complains if we put something else than a string :

>>> import pyelevator
>>> E = pyelevator.Elevator()
>>> E.Put('foo', 'bar')
>>> E.Put('key', ['foo', 12])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/yannick/.virtualenvs/onitu/lib/python2.7/site-packages/pyelevator/client.py", line 46, in Put
    self.send(self.db_uid, 'PUT', [key, value], *args, **kwargs)
  File "/home/yannick/.virtualenvs/onitu/lib/python2.7/site-packages/pyelevator/base.py", line 132, in send
    raise ELEVATOR_ERROR[header.err_code](header.err_msg)
TypeError: Unsupported value type : <type 'list'>

I don't see any reason not to handle serialization/deserialization of common types as msgpack is already used.

[oleiade]

I'll try to figure out something generic enough. While we're at implementing native client serialization, let's try to provide an internal interface to messages serialization too. :+1:

[k4nar]

Internal, like in Elevator ? I'm not sure to how that could be possible.

[oleiade]

Nope sorry I meant "privately throught the Client object, py-elevator side".

[k4nar]

Hum, not sure to see what you mean by that.

[k4nar]

I'm not sure how we should do this. I did a quick hack (https://github.com/onitu/py-elevator/commit/ee95784a181f0ed982ec19d9ae64433ff23136d2) in order to get it working, but serializing the message twice is not really elegant (and I'm not handling MGet and batches of course, but it wasn't the point).

[k4nar]

Now I've something which should be working pretty well (cf #48). I didn't find a way to make the serialization global, so I had to handle it in every function concerned.

If you find a more elegant approach, I'm all ears :) .