An experimental implementation of a protocol for machine-readable cache policies in OGC and ISO geoservices. The protocol is described in this paper: A protocol for machine-readable cache policies in OGC web services: Application to the EuroGeoSource information system. If you do not have access to the full document, the author's final version (with almost exactly the same content) is available at http://iaaa.cps.unizar.es/curriculum/08-Publicaciones-Articulos/art_2014_EMS_Protocol_vdef_author.pdf.
Full citation:
A protocol for machine-readable cache policies in OGC web services: Application to the EuroGeoSource information system. R. BÉJAR, F.J. LOPEZ-PELLICER, J. NOGUERAS-ISO, F.J. ZARAZAGA-SORIA, P.R. MURO-MEDRANO. Environmental Modelling & Software. 2014, vol. 60, p. 346-356, doi:10.1016/j.envsoft.2014.06.026.
Take into consideration that this code is not robust or production-ready; it is an experiment to test if the mentioned protocol can be implemented as proposed, and to show how that could be done.
You need a Python 2.7.x interpreter to run this program. It has been developed and tested in Python 2.7.3 in Linux, but it should run in any other platform that supports Python 2.7.x
Besides a number of Python 2.7 standard libraries, you need OWSLib 0.8.7, which allows to use OGC services from Python code. You can find out more information about this library (including the license terms) in https://geopython.github.io/OWSLib/. I have included the sources of this library in the repository to make it easier to clone and test this, but that is clearly a quick-and-dirty solution.
On Linux, you can clone the repository locally with this command:
git clone https://github.com/rbejar/odrl-ogc-cache-policies
After that, you can give ODRL_Paper.py file run permission and then run it:
cd odrl-ogc-cache-policies
chmod u+x ODRL_Paper.py
./ODRL_Paper.py
As long as you have Python 2.7.x installed, this will work. This is the result of a run of this program:
###### TEST1 #####
Have you reviewed and agreed to the archive policies of http://mularroya05.cps.unizar.es:8081/geoserver/TestODRL3/wfs? (Y/N): y
For this service:
- http://mularroya05.cps.unizar.es:8081/geoserver/TestODRL3/wfs
Cache this content:
- Content id: Full Service
- Request_rate?: False
- Archive time limit?: False
###### TEST2 #####
Have you obtained the consent to archive http://mularroya05.cps.unizar.es:8081/geoserver/TestODRL1/wfs#TestODRL1:archsites? (Y/N): y
Have you reviewed and agreed to the archive policies of http://mularroya05.cps.unizar.es:8081/geoserver/TestODRL1/wfs#TestODRL1:archsites? (Y/N): y
For this service:
- http://mularroya05.cps.unizar.es:8081/geoserver/TestODRL1/wfs
Cache this content:
- Content id: http://mularroya05.cps.unizar.es:8081/geoserver/TestODRL1/wfs#TestODRL1:archsites
- Request_rate?: True
(Times per minute:5)
- Archive time limit?: True
(Number of months: 6)
###### TEST3 #####
Caching has not been allowed for the services and contents requested
###### TEST4 #####
Have you reviewed and agreed to the archive policies of http://mularroya05.cps.unizar.es:8081/geoserver/TestODRL3/wfs#TestODRL3:states? (Y/N): y
For this service:
- http://mularroya05.cps.unizar.es:8081/geoserver/TestODRL3/wfs
Cache this content:
- Content id: http://mularroya05.cps.unizar.es:8081/geoserver/TestODRL3/wfs#TestODRL3:states
- Request_rate?: False
- Archive time limit?: False
###### TEST5 #####
Have you obtained the consent to archive http://mularroya05.cps.unizar.es:8081/geoserver/TestODRL1/wfs#TestODRL1:archsites? (Y/N): y
Have you reviewed and agreed to the archive policies of http://mularroya05.cps.unizar.es:8081/geoserver/TestODRL1/wfs#TestODRL1:archsites? (Y/N): y
For this service:
- http://mularroya05.cps.unizar.es:8081/geoserver/TestODRL1/wfs
Cache this content:
- Content id: http://mularroya05.cps.unizar.es:8081/geoserver/TestODRL1/wfs#TestODRL1:archsites
- Request_rate?: True
(Times per minute:5)
- Archive time limit?: True
(Number of months: 6)
For this service:
- http://mularroya05.cps.unizar.es:8081/geoserver/TestODRL1/wfs
Cache this content:
- Content id: http://mularroya05.cps.unizar.es:8081/geoserver/TestODRL1/wfs#TestODRL1:roads
- Request_rate?: True
(Times per minute:5)
- Archive time limit?: False
###### TEST6 #####
For this service:
- http://mularroya05.cps.unizar.es:8081/geoserver/TestODRL1/wfs
Cache this content:
- Content id: http://mularroya05.cps.unizar.es:8081/geoserver/TestODRL1/wfs#TestODRL1:roads
- Request_rate?: True
(Times per minute:5)
- Archive time limit?: False
Three OGC WFS services have been set up using Geoserver to test the protocol (ODRL_Paper.py reads their capabilities to extract the ODRL licenses as the protocol requires). Creating an OGC web service with Geoserver that uses the protocol is simple: you set it up as usual with the Geoserver web administration tool, and right there you include the text you want in the Acess Constraints section. As long as that text includes an URL with a valid ODRL file (that can be hosted wherever you prefer), you are ready.
These are the three services get capabilites requests:
- http://mularroya05.cps.unizar.es:8081/geoserver/TestODRL1/wfs?request=GetCapabilities
- http://mularroya05.cps.unizar.es:8081/geoserver/TestODRL2/wfs?request=GetCapabilities
- http://mularroya05.cps.unizar.es:8081/geoserver/TestODRL3/wfs?request=GetCapabilities
And these are the three ODRL license files that are linked from the Access Constraints section on those capabilities (hosted on github.io, but they could be anywhere):