Re: [Qgis-developer] WPS server
Hi Martin, I think we need both : * QgsExpression for simple Process on Geometry and simple parameters * SEXTANTE for complexe Process on Raster, Vector Layer, multiple Layer, etc After some tests on WFS-Transaction, I need a way to validate my geometry before updating or adding feature. In this case SEXTANTE will be too big, QgsExpression is exactly what I need no more no less. I do not need to Process layer. For SEXTANTE, Vincent Picavet give the good solution : /* Making sextante totally independant of qgis GUI, to be able to run sextante processes in batch in command line mode// //This will open the door to use Sextante as a real WPS processes generator, // //with features not unlike an ETL (or ELT)./ René-Luc D'Hont 3Liz Le 03/12/2012 17:43, Martin Dobias a écrit : On Mon, Dec 3, 2012 at 2:31 PM, rldhont rldh...@gmail.com mailto:rldh...@gmail.com wrote: My idea was to have a simple WPS server based on QGIS-Server, very simple for simple vector case, and I thought it's a good idea. I only need to validate geometry, constructing simple buffer or intersection. For big processing, I think SEXTANTE is better suitable, but for a WPS serveur, SEXTANTE didn't need QGIS. We can construct a WPS Server based on pySextante with pyWPS. I don't really want to hack QgsExpression, just accesses to very simple processing, I'll just it. For SEXTANTE, It will be better to work on someting based on pyWPS. I don't think PyWPS would be a good choice for WPS server implementation. From a broader view, PyWPS does the same thing as SEXTANTE does: it allows users to run processes and it allows developers to provide custom processes. The main difference is that PyWPS processing is meant to be triggered by WPS requests, while SEXTANTE processing may be triggered by anything (currently mainly GUI). On the backend side, PyWPS supports GRASS, while SEXTANTE offers much more by default. It's true that one could attach SEXTANTE to PyWPS and let QGIS server call PyWPS all the time, but that would bring just additional limitations. In fact, the server-side WPS support could be implemented directly within SEXTANTE, the only thing that would QGIS server do would be to pass WPS request to SEXTANTE routine and send its response back to server. So the bottom line from my point of view: SEXTANTE +1 QgsExpression -1 PyWPS -1 Regards Martin ___ Qgis-developer mailing list Qgis-developer@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-developer
Re: [Qgis-developer] WPS server
Hi Paolo, Hi Luca, Hi all, I'll explain my idea about QGIS-Server and WPS implementation. For the next QGIS release, 3Liz has decided to improve QGIS-Server WFS implementation. The main improvement is to cover the maximum of the 1.0.0 standard, especially Transaction. For Transaction and GetFeature Request, I needed to extend the QGIS Expressions directly in the QGIS core. I added some spatial operators like Intersects, Contains, Disjoint but I also added spatial constructor like geomFromWKT, Intersection, buffer. The last point means that it's possible to construct a buffer with the QGIS Expression system. I also discovered that in the Filter Encoding OGC standard, it's possible to use Functions and the QGIS Expression system provides a reader for this way of describing expressions. And Nathan Woordrow publishing 'User defined expression functions for QGIS' on his blog http://woostuff.wordpress.com/2012/11/10/user-defined-expression-functions-for-qgis/ . This point explaining how the new QGIS Expression system is extendable. And for me it was the start for testing a WPS implementation, because I needed WPS for validating geometry for the WFS Transaction Request. I've worked on a WPS project which provides a way to create Process in a wide range of programming langage, the ZOO-Project. I've worked on the JavaScript Provider. In this project, you have to code to create new process. With the QGIS Expression you just have to know how to write an expression to create a new Process. It's not coding. For example the Buffer Process can be described like this : buffer(geometry,distance) You want to create a Process which retrun the buffer without the geometry : difference(buffer(geometry,distance),geometry) And we can define a Process which return the result of a QGIS Expression as the Process parameter. My plan for WPS implementation is firstly to find fund, to : * implement the standard (defining how to declare process, how to use the posting XML for Excute Request, how to use QGIS layer from project, etc) * loading Python scripts for 'User defined expression functions' * Using Sextante Sextante is not my priority because it is more complexe, the QGIS-Server doesn't load python and python plugins, and we firstly need to provide a way to have simple Process and simple way to describe Process, after that it will be easy to use SEXTANTE. Regards, René-Luc D'Hont 3Liz ___ Qgis-developer mailing list Qgis-developer@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-developer
Re: [Qgis-developer] WPS server
Hi Rene-Luc On Mon, Dec 3, 2012 at 10:01 AM, rldhont rldh...@gmail.com wrote: With the QGIS Expression you just have to know how to write an expression to create a new Process. It's not coding. For example the Buffer Process can be described like this : buffer(geometry,distance) You want to create a Process which retrun the buffer without the geometry : difference(buffer(geometry,**distance),geometry) And we can define a Process which return the result of a QGIS Expression as the Process parameter. Thanks for sharing your thoughts about your implementation. I would like to express my concerns that using QgsExpression may be a dead end for a generic WPS servers. Expressions are meant to deal with individual features of a vector layer. You're right that it's possible to define your own functions and chain them to create processes, but this is very limited. For example it's not possible for a process to return more results and it's not possible to use one result more than once. Just like raster calculator has its own expression engine, also the processing service should use a way of describing algorithms that suits best its needs - and in our case that's python+SEXTANTE. Therefore I strongly recommend using SEXTANTE for the WPS server backend. I believe that would be less work than trying to hack QgsExpression to use it for processing. You would just need to parse WPS query, generate a Python script that would run SEXTANTE analysis and then create WPS reply. It's probably not desirable to run the processing directly within the server process (thread), so this would be a better solution either way. Regards Martin ___ Qgis-developer mailing list Qgis-developer@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-developer
Re: [Qgis-developer] WPS server
Le 03/12/2012 14:05, Martin Dobias a écrit : Hi Rene-Luc On Mon, Dec 3, 2012 at 10:01 AM, rldhont rldh...@gmail.com mailto:rldh...@gmail.com wrote: With the QGIS Expression you just have to know how to write an expression to create a new Process. It's not coding. For example the Buffer Process can be described like this : buffer(geometry,distance) You want to create a Process which retrun the buffer without the geometry : difference(buffer(geometry,distance),geometry) And we can define a Process which return the result of a QGIS Expression as the Process parameter. Thanks for sharing your thoughts about your implementation. I would like to express my concerns that using QgsExpression may be a dead end for a generic WPS servers. Expressions are meant to deal with individual features of a vector layer. You're right that it's possible to define your own functions and chain them to create processes, but this is very limited. For example it's not possible for a process to return more results and it's not possible to use one result more than once. Just like raster calculator has its own expression engine, also the processing service should use a way of describing algorithms that suits best its needs - and in our case that's python+SEXTANTE. Therefore I strongly recommend using SEXTANTE for the WPS server backend. I believe that would be less work than trying to hack QgsExpression to use it for processing. You would just need to parse WPS query, generate a Python script that would run SEXTANTE analysis and then create WPS reply. It's probably not desirable to run the processing directly within the server process (thread), so this would be a better solution either way. Hi Martin, My idea was to have a simple WPS server based on QGIS-Server, very simple for simple vector case, and I thought it's a good idea. I only need to validate geometry, constructing simple buffer or intersection. For big processing, I think SEXTANTE is better suitable, but for a WPS serveur, SEXTANTE didn't need QGIS. We can construct a WPS Server based on pySextante with pyWPS. I don't really want to hack QgsExpression, just accesses to very simple processing, I'll just it. For SEXTANTE, It will be better to work on someting based on pyWPS. René-Luc Regards Martin ___ Qgis-developer mailing list Qgis-developer@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-developer
Re: [Qgis-developer] WPS server
On Mon, Dec 3, 2012 at 2:31 PM, rldhont rldh...@gmail.com wrote: My idea was to have a simple WPS server based on QGIS-Server, very simple for simple vector case, and I thought it's a good idea. I only need to validate geometry, constructing simple buffer or intersection. For big processing, I think SEXTANTE is better suitable, but for a WPS serveur, SEXTANTE didn't need QGIS. We can construct a WPS Server based on pySextante with pyWPS. I don't really want to hack QgsExpression, just accesses to very simple processing, I'll just it. For SEXTANTE, It will be better to work on someting based on pyWPS. I don't think PyWPS would be a good choice for WPS server implementation. From a broader view, PyWPS does the same thing as SEXTANTE does: it allows users to run processes and it allows developers to provide custom processes. The main difference is that PyWPS processing is meant to be triggered by WPS requests, while SEXTANTE processing may be triggered by anything (currently mainly GUI). On the backend side, PyWPS supports GRASS, while SEXTANTE offers much more by default. It's true that one could attach SEXTANTE to PyWPS and let QGIS server call PyWPS all the time, but that would bring just additional limitations. In fact, the server-side WPS support could be implemented directly within SEXTANTE, the only thing that would QGIS server do would be to pass WPS request to SEXTANTE routine and send its response back to server. So the bottom line from my point of view: SEXTANTE +1 QgsExpression -1 PyWPS -1 Regards Martin ___ Qgis-developer mailing list Qgis-developer@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-developer
Re: [Qgis-developer] WPS server
2012/12/3 Martin Dobias wonder...@gmail.com: I don't think PyWPS would be a good choice for WPS server implementation. From a broader view, PyWPS does the same thing as SEXTANTE does: it allows users to run processes and it allows developers to provide custom processes. The main difference is that PyWPS processing is meant to be triggered by WPS requests, while SEXTANTE processing may be triggered by anything (currently mainly GUI). On the backend side, PyWPS supports GRASS, while SEXTANTE offers much more by default. It's true that one could attach SEXTANTE to PyWPS and let QGIS server call PyWPS all the time, but that would bring just additional limitations. I don't know really well PyWPS, but I think that you can use more that GRASS for sure at least R. Other WPS Server as ZOO or 52north and maybe also GeoServer permit to the user to create services with a lot of libraries, I'm using ZOO and I can use much more than Sextante ;-) Regards Martin -- ciao Luca http://gis.cri.fmach.it/delucchi/ www.lucadelu.org ___ Qgis-developer mailing list Qgis-developer@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-developer
[Qgis-developer] WPS server
Hi all. Is anybody working (or planning to) on a WPS server implementation for QGIS? Does anybody have an estimate of how much work would be involved? Ideally, it would be good to build it on top of sextante, so to have the full set of algorithms and models immediately available. Thanks. -- Paolo Cavallini - Faunalia www.faunalia.eu Full contact details at www.faunalia.eu/pc Nuovi corsi QGIS e PostGIS: http://www.faunalia.it/calendario ___ Qgis-developer mailing list Qgis-developer@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-developer
Re: [Qgis-developer] WPS server
Hi Paolo, I'm starting some WPS implementation based on QgsExpression, and it's working. I'll publish my first code. René-Luc Le 2 déc. 2012 09:25, Paolo Cavallini cavall...@faunalia.it a écrit : Hi all. Is anybody working (or planning to) on a WPS server implementation for QGIS? Does anybody have an estimate of how much work would be involved? Ideally, it would be good to build it on top of sextante, so to have the full set of algorithms and models immediately available. Thanks. -- Paolo Cavallini - Faunalia www.faunalia.eu Full contact details at www.faunalia.eu/pc Nuovi corsi QGIS e PostGIS: http://www.faunalia.it/calendario ___ Qgis-developer mailing list Qgis-developer@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-developer ___ Qgis-developer mailing list Qgis-developer@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-developer
Re: [Qgis-developer] WPS server
Il 02/12/2012 13:24, René-Luc D'Hont ha scritto: I'm starting some WPS implementation based on QgsExpression, and it's working. I'll publish my first code. wow, great news. looking forward to it. merci beaucoup. -- Paolo Cavallini - Faunalia www.faunalia.eu Full contact details at www.faunalia.eu/pc Nuovi corsi QGIS e PostGIS: http://www.faunalia.it/calendario ___ Qgis-developer mailing list Qgis-developer@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-developer
Re: [Qgis-developer] WPS server
Hi Renè 2012/12/2 René-Luc D'Hont rldh...@gmail.com: I'm starting some WPS implementation based on QgsExpression, and it's working. could you explain a little bit more about your idea? what languages/library will be supported by the services? I'll publish my first code. René-Luc Thanks -- ciao Luca http://gis.cri.fmach.it/delucchi/ www.lucadelu.org ___ Qgis-developer mailing list Qgis-developer@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-developer
Re: [Qgis-developer] WPS server
Il 02/12/2012 13:24, René-Luc D'Hont ha scritto: Hi Paolo, I'm starting some WPS implementation based on QgsExpression, and it's working. Any plan to expand it to use more functions? As said, using sextante would be the real killer here. Thanks. -- Paolo Cavallini - Faunalia www.faunalia.eu Full contact details at www.faunalia.eu/pc Nuovi corsi QGIS e PostGIS: http://www.faunalia.it/calendario ___ Qgis-developer mailing list Qgis-developer@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-developer
