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Kendo for browsing large geospatial databases?

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Dr.YSG
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Dr.YSG asked on 05 Mar 2012, 09:17 PM
We have a 20 Million record table in PostGIS (spatial version of PostGRESQL). There are 18 columns (mostly text, some integer) and one spatial geometry (a bounding box).

The records describe the metadata for geospatial images (GeoTiffs, etc.)

We are looking for a means for a user to browse and search this database.

While I am very familiar with your silverlight offering Which does a have a map (and that is the overview we might like).

I am not familar with  your back-end database, nor your new KENDO HTML5 product.

Our target client platform is Android, IOS, Web Browsers, and plugins to existing tools (GoogleEarth GoogleMaps, WorldWind). So Silverlight is not a good choice.

Can you help me determine which of your products I should be looking at for the back end?
(ORM? I already have a PostGIS .NET API, but if yours works faster that would be fine).

As well as what I should have on the client? (Kendo? But it does not have a map. Do I use OpenLayers?) We also want grid and chart displays of the results.

As well as the protocol that would be connecting the two: (JSON? But what if I have 4,000 records returned? Can I GZIP the response). I assume I want to virtualize the replies.

Thank you

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Serge
Telerik team
answered on 08 Mar 2012, 11:45 AM
Hello,

 The Kendo DataSource supports data in JSON format. I am sure you could apply GZIP compression on your JSON to reduce its size. Most web servers support automatic GZIP compression of everything. Virtualization is supported by the Kendo Grid widget and can be seen working in this online demo.
 
 Currently there is no map widget in Kendo UI but this is definitely on our radar. We are not familiar with OpenLayers and cannot comment whether you should use it or not.

 I am not sure what your needs for backend access are. Telerik OpenAccess has geospatial data support. You can check this blog post for further information. The example is also available in the the OpenAccess SDK.

Regards,
Serge
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Dr.YSG
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answered on 09 Mar 2012, 04:44 PM
Let me clarify my question. I don't think it is clear yet.

Issue: we have 21 Million records in a single table in a PostGreSQL/PostGIS database.
column attributes are mostly time/date stamps, simple text fields (type) and one geometry field (bounding box/ bbox).

We want users to search/query from Kendo with (AJAX/JQUERY ?) . At the server the search will look like REST GET requests. The key part of the REST request is a parameter called bbox which is used as a filter to restrict the query to small area. Timestamp ranges will also be part of the search filter.

On the server side, a WCF data service will receive the AJAX request, convert it into SQL SELECT request (we need to use WHERE clauses with the ST_INTERSECT() spatial functions to optimize performance). We are planning of using DevArt DotConnect for PostGreSQL for the .NET database API. We are not clear if an ORM really will help us, or hurt our performance.

The result records (18 fields of meta data fields per row) will be returned via Microsoft WCF ODATA (in JSON format) to the JQUERY and then data mapped to both GRID and Chart displays.

Data might have to be paged via ODATA paging services on the server (or should we do this on the client, since the return sets should be fairly small. on the order of 10 to 1000).

1. Does anything of what I said sound stupid, based on best practices (I cannot change the choice of PostGIS or KENDO) and since the server is a windows 7 machine and we are VisualStudio C# programmers WCF sounds like a better way that JAVA, Glassfish, Apache, etc.

2. What we really need is samples of any of the steps that I outlined that we can use as design ideas for what we are doing.

3. Any caveats and gotchas we should be concerned about in doing this project with these tools?

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Atanas Korchev
Telerik team
answered on 09 Mar 2012, 05:41 PM
Hello,

Up to your questions
  1. Everything sounds doable. The Kendo DataSource supports binding to OData services or WCF.
  2. You can check our grid remote binding example (the grid is bound to OData). You can also browse our github repository of ASP.NET examples.
  3. One of the things to have in mind is that WCF and OData do not work by default with JSONP (which is needed for cross domain access). You need to use some code to enable this as shown in this blog post.

Regards,
Atanas Korchev
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Noli
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answered on 19 Apr 2012, 05:24 AM
Leaflet is better than Openlayers. It supports GeoJSON out of the box.

http://leaflet.cloudmade.com/examples/geojson.html

CartoDB (i.e. PostGIS) is really good in serving GeoJSON thru Ajax for Leaflet.

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Benton
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answered on 18 Jul 2012, 08:28 PM
Hi, 

Which mapping technology did you decide to leverage in your solution?  If you haven't found one yet, take a look at our MapDotNet technology.  www.mapdotnet.com

We have an HTML5 map control that you can easily use with Kendo UI and we have REST services for integration with PostGIS as well as SQL 08/12/Azure, Oracle Spatial and Esri's ArcSDE.

Here's a link to our HTML5 iSDK.... http://apps.mapdotnet.com/HTML5/iSDK/isc.rim.isdk.htm 

Benton
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Dr.YSG
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answered on 18 Jul 2012, 08:40 PM
Interesting.

But In our case we don't need your back-end services (we already have the PostGIS, WCF, and AJAX crude services).

I can't figure if you sell your HTML5 control separately, and/or what are the run-time license restrictions.

(Leaflet seems to be free), which is a plus for our sponsor (contractually easier for them).



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Benton
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answered on 18 Jul 2012, 08:56 PM
You can use our HTML5 map control royalty free (we only license our web services).  Our freehand drawing support (which I don't believe Leaflet offers) works nicely in the iOS and Android browsers. http://apps.mapdotnet.com/HTML5/iSDK/isc.rim.isdk.spatialQuery.htm 

With your drawn shape you can pass it to through the REST services to perform a spatial query on a table in PostGIS or save that draw shape into PostGIS.  The other big advantage is our map rendering service which can render map tile overlays on-the-fly from PostGIS table.  This allows you to render lots of data on tiles server-side so you can overcome limitations of rendering large amounts of data client side.

In case you're interested, we're working on advanced geospatial data collection tool based on Kendo UI mobile that will showcase how to do the advanced drawing and shape editing mentioned above.

Benton
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Dr.YSG
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answered on 18 Jul 2012, 09:01 PM
Thank you,

Note, we have 20M to 100M objects (image, or vector) and the total storage is in the order of Terabytes, so I would not store this in PostGreSQL/PostGIS

The tiling is needed since some blobs are a little large for clients. I am going to contact you via email.
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Dr.YSG
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