GML versus JSON when providing Geographical Data, speed and size factors

ctuot — 2007-08-03T08:56:00Z

So here is the situation: I need to process some spatial information which I retrieve from different servers using the OGC standard WFS protocol. I simply use the GeoTools to query and process the information.

Information providers are all partners using either GeoServer or UMN Mapserver. All providers have a relative good internet connection in terms of speed but try as much as possible to spare some bandwidth (In Europe, a lot of internet connections are still volume based).

If I tell you that some spatial information stored in GML format requires more space than when stored in JSON format, you certainly will not be surprised. But about how much extra space are we exactly talking?

Since the GeoServer supports both delivery in GML and JSON format, I decided to give a quick shot to get a better idea about speed and size differences between GML and JSON.

The spatial information I used is stored in Oracle 10g and accessible through a GeoServer in a Gigabit Network.

Here are the queries I used:

for GML: wfs?SERVICE=WFS&VERSION=1.0.0&REQUEST=GetFeature&TYPENAME=topp:ACKERFLAECHEN_RLP_GK3
for JSON: wfs?request=GetFeature&typename=topp:ACKERFLAECHEN_RLP_GK3&outputformat=json

All caching mechanisms have been disabled!

Here the results:

Delivery time:

WFS: 12,33s
JSON: 8,86s

Result size:

WFS: 235 MB
JSON: 157 MB

Of course, there are many other aspects besides speed and size which should be taken into consideration like for example validation issues.

Nevertheless, JSON spares a lot of bandwidth and for slower internet connections, this means sparing a lot of time when providing information.

towards the geospatial semantic web (Semanticaly enabled Spatial Decision Support System) : topic:GIS

GML versus JSON when providing Geographical Data, speed and size factors