Aspect (or property) with Geometry, Geo-Spatial Data type.

[steve_tekell]

Is it feasible to add geo-spatial information into Alfresco (or any JCR)?
I would like to associate content items with spatial data - points, polygons, etc.  Something stored in a spatial (geometry) typed column, so that it can be properly indexed and queried.  There would then be some UI (google maps, ESRI+Dojo) to input geometry for an item and query for items spatially as well.

Currently a custom model supports types like decimal, date, text, etc, but nothing for geo-spatial data.

How would you add a spatial data type to a custom model in Alfresco?
What plans does Alfresco have to support geo-spatial information?

At this point it doesn't look feasible to do this within Alfresco or any JCR.

BTW There is Hibernate Spatial to add Hibernate user types for geometry data type.  However, MySQL InnoDB (Alfresco's default) doesn't support spatial indexes.  PostgreSQL (w/PostGIS) and Oracle are better choices for this.

[jck]

Hi,
could you please give an example of a geo-spatial query?

In which way a specialized storage engine can process it in comparison with usual database engines?

JC

[mbailen]

See the PostGIS site for information on a specialized storage engine:  http://postgis.refractions.net/

You can find lots of queries in their doc.  Example, page through http://postgis.refractions.net/documentation/manual-1.4/ch04.html#id2717073

bnordgren: we intend to revisit some of the Lucene solutions (e.g. Local Lucene), to see what sort of performance/functionality we can get with Alfresco.  Not sure about GeoNetwork.  I think we looked at it and determined that using it would render much of the DMS functionality of Alfresco useless.  This is pretty much what you were driving at in your previous post.  Alfresco adds a lot at ingestion time… e.g. meta-data extraction, version control, ftp-access, categorizing, etc., that we like.

[bnordgren]

bnordgren: we intend to revisit some of the Lucene solutions (e.g. Local Lucene), to see what sort of performance/functionality we can get with Alfresco.  Not sure about GeoNetwork.  I think we looked at it and determined that using it would render much of the DMS functionality of Alfresco useless.  This is pretty much what you were driving at in your previous post.  Alfresco adds a lot at ingestion time… e.g. meta-data extraction, version control, ftp-access, categorizing, etc., that we like.

Excellent.  Please keep me updated. I missed the "Local Lucene" solution.

In terms of the "GeoNetwork" solution, GeoNetwork doesn't ingest anything, it merely catalogs it. It's mostly designed to poll geospatial servers in order to present a consilidated list of what "stuff" exists on which servers. If GeoNetwork were to be used, I think I'd suggest developing a CMIS backend to it so that it could poll CMIS repositories too. Presumably the query would look something like : "select all documents with geospatial properties which have been updated since the last time I polled you". "Geospatial Properties" would/should look like normal text properties to Alfresco, and should contain the geometry in well known text (WKT).  Alternatively, complex geospatial properties could be represented as an "association to" a Geographic Markup Language file. I believe GeoNetwork could also harvest any non-geospatial properties attached to the CMIS objects, making mixed searches possible.

Whatever route you take, I'd love to hear how this turns out!

[bnordgren]

This is an interesting comment in the "local lucene" svn repository:

Revision 172 - Directory Listing
Modified Wed Apr 29 03:49:25 2009 UTC (13 months ago) by pjaol

Updated to latest version of lucene and solr
fixed a multireader issue
migrated to use spatial lucene instead of locallucene
locallucene is dead, long live spatial lucene‍‍‍‍‍‍‍

Which I think brings us back to the spatial extension for Lucene. But wait, take a look at this: http://www.jteam.nl/products/spatialsolrplugin.html.  It even looks to be commercially supported if that's your style…

[janvg]

To answer your question yes it is feasible to add geo-spatial types.    However as you have no doubt concluded the current version of Alfresco does not support these types and there would be issues with database support and the query engine. 

This would make an interesting project for an extension to Alfresco.   

How many people would make use geo-spatial searching if Alfresco supported it?

I do believe geo-spatial types should be on top of Alfresco's road map.  It would be very interesting to add geo data when uploading a document , but even more important might be that one can tag documents with geo-data.