APyMongo

Info: A tornado-based asynchronous version of the pymongo driver for MongoDB.

Author: Dan Yamins [email protected]

About

APyMongo is an asynchronous version of the PyMongo driver for MongoDB. APyMongo uses the tornado iostream eventloop to drive asychronous requests. A primary use of APyMongo is to serve MongoDB-backed websites in an efficient asynchronous manner via the tornado web server, but it can be used wherever one wants to drive multiple efficient highthrouput read-write connections to a MongoDB instance.

Installation

For now, the project is just a github repo (https://github.com/yamins81/apymongo].

The install process is:

1. install mongodb if you havent already
2. pull the apymongo repo
3. run "python setup.py install" in the apymongo directory.

Dependencies

Mongo: APyMongo works for the same MongoDB distributions that PyMongo works on.

Python: APyMongo requires Python >=2.4.

Tornado: IMPORTANT!!! You MUST must be using the a recent pull from the Tornado repository to
run APyMongo. APyMongo depends on a recent addition to the tornado.iostream module that is NOT present in the current release.

Additional dependencies are:

• (to generate documentation) sphinx
• (to auto-discover tests) nose.

Examples

Here's a basic example that can be used in a Tornado web server:

import json
import tornado.web

import apymongo 
from apymongo import json_util
	
class TestHandler(tornado.web.RequestHandler):

	@tornado.web.asynchronous
	def get(self):     
		connection = apymongo.Connection()		
		collection = conn['testdb']['testcollection']
		coll.find_one(callback=self.handle)
		
	def handle(self,response):
		self.write(json.dumps(response,default=json_util.default))
		self.finish()

For more information, see the examples section of the docs. To use a given example:

1. Make sure you have installed mongo and apymongo (and tornado), and that a MongoDB instance is running on localhost:27017 (the default).

2. cd /path/to/apymongo/doc/examples

3. python [desired_example_file.py]

4. Open a web broweser and point it to localhost:8000

Documentation

Currently, there is no separate documentation for this project. Essentially, APyMongo's API is identical to pymongo's except for the following:

• Every pymongo method that actually hits the database for a response now has a callback argument, a single-argument executable to which tornado will pass the contents of the response when it is ready to be read. In other words, you can no longer do e.g.:

  r = collection.find_one()

but must instead do e.g.:

def callback(r):
    #handle response ... 

collection.find_one(callback)

This goes for ALL methods that hit the database, including even such ``simple" things as connection.database_names.

• Cursors have no next method. Instead, to obtain the equivalent of ``list(cursor.find())", use the apymongo.cursor.loop method.

• The Connection method has a io_loop argument, to which you can pass an existing tornado.io_loop object for the streams to attach to.

Testing

The easiest way to run the tests is to install nose via easy_install nose) and run nosetests or python setup.py test in the root of the distribution. Tests are located in the test/ directory.

Currently, the tests are very scant (and, something using the tornado.testing framework is not working quite right ...)

Limitations

APymongo currently does not handle:

• master-slave connections
• DBRefs.
• the explain method

Relationship to asyncmongo

APyMongo was originally developed for the GovData project (https://github.com/yamins81/govdata-core), where a version of it is buried deep in the govdata code. While APyMongo was being modularized for separate relase, I learn of asyncmongo, an existing asynchronous python-language MongoDB driver that also uses the tornado iostream.

Because asyncmongo has a somewhat different API, I decided to release APyMongo as a separate project.