dataproxy 0.1.0

Data Proxy: a google app-engine application for proxying data to json (jsonp) format.

Author: James Gardner <http://jimmyg.org>
Author: Stefan Urbanek <stefan.urbanek@gmail.com>

Transformation modules
======================

For each resource type there should be a module in transform/<type>_transform.py

Each module should implement:
* ``transformer(flow, url, query)``, should return a Transformer subclass
* Transformer subclass with __init__(flow, url, query)

Existing modules:
* transform/csv_transform - CSV files
* transform/xls_transform - Excel XLS files


Random notes
============

Mount point
Maximum file size

http://someproxy.example.org/mount_point?url=url_encoded&sheet=1&range=A1:K3&doc=no&indent=4&format=jsonp

Response format:

header
url = http://...file.xls
option = 'row=5&row=7&row_range=10:100000:5000',
response
sheet = 'Sheet 1',
data = [
[...],
[...],
[...],
]

* Downloading the entire spreadsheet
* Downloading a single sheet (add ``sheet=1`` to the URL)
* Downloading a range in a single sheet (add ``range=A1:K3`` to the URL) [a bit nasty for CSV files but will do I think]
* Choosing a limited set of rows within the sheet (add ``row=5&row=7&row_range=10:100000:5000`` - rowrange format would be give me a row between 10 and 100000 every 5000 rows)


Hurdles
-------
* Some data sets are not in text-based formats => Don't handle them at this stage
* Excel spreadhseets have formatting and different types => Ignore it, turn everything into a string for now
* Some data sets are huge => don't proxy more than 100K of data - up to the user to filter it down if needed
* We don't want to re-download data sets => Need a way to cache data -> storage API
* Some applications might be wildly popular and put strain on the system -> perhaps API keys and rate limiting are needed so that individual apps/feeds can be disabled. How can we have read API keys on data.gov.uk?