Re: MongoDB Reader

Hey Scott,

I haven't heard of anyone doing this sort of work. In general, most of the VTK-related work with database
queries seems to come from the statistics and information visualization side, rather than the large data
scientific visualization folks which ParaView is traditionally aimed towards. So, you get people doing
SQL queries to produce a VTK table, and from there the various things you can do with that.

It's not clear from your email what type of data you would be wanting to visualize with ParaView, and how the
data in MongoDB would be structured. One large issue (and a reason you don't see much work in this
direction) is that even if you store something like point coordinates in your database, you also need to
describe the topology of the structures you're going to build with those points, whether that means just
point vertices, or polygons of some sort, or regular grids. There just aren't any standard data formats
which include something like a document-based NoSQL database for storing the data. The analogy that
comes to my mind for something similar that ParaView can handle is the XDMF file format (xdmf.org). In this
format, an HDF5 file can be used to store the data, but since that file format is so general and flexible,
they need an XML file to go with the data which describes the topology, time steps, etc., and where to look in
the HDF5 file for that information. You would have a similar issue, that MongoDB is almost infinitely
flexible, and so unless there is a large community using it for similar purposes, who is willing to come up
with a standard data format stored in the DB, there probably won't be something pre-made that you can use.

Now, on a more optimistic note, :), I tried a few minutes ago and had some success with reading information
from a MongoDB database into ParaView using the Python Programmable Source. Some examples for creating
data are here:

http://www.paraview.org/Wiki/Python_Programmable_Filter#Generating_Data_.28Programmable_Source.29

I had pymongo installed for the version of Python that ParaView 3.14 (downloaded binary, Mac OS X 10.7)
happens to use (which I didn't know, but found by printing out sys.path and saw that it included
/Library/Python/2.5/site-packages so my Python 2.5 was being used). You can see from the attached PNG
image that I didn't generate any real geometric data to display, but I accessed MongoDB and queried it and