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Re: DDE, Debian Data Export

On Wed, Feb 11, 2009 at 05:08:52PM +0100, Andreas Tille wrote:

> On Wed, 11 Feb 2009, Enrico Zini wrote:
>> DDE exports data as a big virtual tree.  You can pick a node in the tree
>> by its URL and download all the data that it contains, in a format of
>> your choice: currently it supports JSON/JSONP, YAML, CSV and Python
>> pickled objects.
> I have to admit after a (quick) view about the URLs you gave I did not
> really understand how the data are entering the tree and how I can pull
> the information (it's a shame that I missed your talk).

The data enter the tree by means of plugins, that map branches of the
tree to queries to the places where the information is.  For example, if
you go to http://dde.debian.net/dde/q/udd/packages/prio-debian-lenny/debtags
then DDE will do a query to UDD for you and give you the results.

You can pull the information by simply appending ?t=FORMAT to the URL.
For example: 

The formats supported at the moment are json, yaml, csv and pickle.

>> DDE is not a competitor to UDD (http://wiki.debian.org/UDD): UDD is
>> about creating a central location where all the data can be accessed,
>> while DDE is about giving people a simple way to access data or subsets
>> of data.
> So is DDE actually using UDD as input?

UDD, apt-xapian-index, a Xapian index of apt-file information, static
files in DD's home directories, anything else one may want to write a
plugin for.

>> * A call for action
>> You can add data to the DDE tree by just putting a data file in yaml,
>> json or pickle format under `~/.dde`: I've written a specific guide[1]
>> to this on the Debian wiki, see: http://wiki.debian.org/DDE/HomeFiles
> This is the part I'm curious about.  Please explain in more detail.
> I've written some code which is harvesting data for Blends - if I can
> provide some input I'd be happy to do so.

NOTE: following some thinking on IRC today, the way to publish static
data has changed.  Also, the HomeFiles wiki page has been renamed to

The good news is that the new way is even simpler.

To get started with publishing data in DDE, try this:

 1. Create some data structure in python or any other language with your
    data (you can mix dicts and lists freely, and if in doubt, use dicts).
 2. Save that data structure to disk in Yaml, Json or Pickle format, as
    you prefer.
 3. Log on merkel and put the resulting file in:
    The extension should match the data format that you chose.
 4. Visit http://dde.debian.net/dde/q/sandbox/filename: you will see
    your data.

Note that http://wiki.debian.org/DDE/StaticData also contains examples
that you can run on merkel, as well as links to documentation about the
various supported data formats.



GPG key: 1024D/797EBFAB 2000-12-05 Enrico Zini <enrico@debian.org>

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