Hi Soeren thanks for your further input.
On Fri, Apr 29, 2011 at 10:45 AM, Soeren Gebbert <[email protected]> wrote: >> - WPS servers are IMHO not really widespread yet(?). Surely you can >> install your own on a local computer but I don't think that an average >> user is able to manage it with few clicks. And not everyone has access >> to a fast server in basement. > > IMHO installing a WPS server with different back-ends is no magic. The > web server, the WPS server and the back-ends can be bundled and > installed as easy as QGIS with all its plugins and libraries and third > party dependencies. This is technically no problem and IMHO the > 52North guys are able to provide such an out of the box solution. I agree that technically there are no serious problems. But still adding further layers of software (wps client + wps server with a backend) between user and the underlying analysis library increases the risk of problems with distribution of the software and configuration (e.g. should such bundled WPS server run as a service all the time or only start it on request? should the server be available only for the user who starts it or for everyone?). >> The reasons above make me believe that we shouldn't depend exclusively >> on WPS. In my vision WPS should be simply another provider of >> processing modules next to SAGA, OTB or various other smaller plugins. >> WPS itself simply cannot deliver the rich user interface that we would >> like to provide. > > This is a good point. Maybe you can use the WPS specification as the > base technology and extend it with additional features which will not > break compatibility. Then you will use an OGC standard and you will be > able to integrate WPS processes out of the box in the much more > powerful framework with the possibility of chaining any kind of > processes? I think we are converging to an API very similar to WPS interface. It makes sense to use the WPS specification to match the data types and the protocol - so that building a WPS client and/or WPS server on top of it should be simple. > You will still need wrapper for each software you want to integrate to > wrap there interface into the abstract QGIS process framework. So the > design of a really powerful abstract process framework providing > interaction and stuff is a lot of work and needs plenty of knowledge > about all the software which might be integrated as processes in QGIS. As I explained in one of the previous mails, the framework in my opinion should consist of two concepts: 1. API for execution of modules (WPS-like): describe module, set parameters, execute module, get results. No interactivity at this stage (apart from progress/log information) 2. API for rich user interface for modules: auto-generation of dialogs for modules, facilities for overriding default behavior It needs to be designed properly (not too generic and not too constrained) but I think this is no rocket science. > To get an idea of the amount of work: Several very intelligent people > have designed the WPS specification and they needed several years to > version 1.0.0. Just a side note: standards always take years to get designed and approved. The time and number of people involved in the creation of a specification does not necessarily correlate with its overall usefulness and adoption by the industry. (I am speaking in general, not related to WPS!) > My main concern is the manpower which is needed to implement AND > maintain such a framework as well as the wrapper and binding for other > software packages. For example the GRASS GIS integration in QGIS. If > there is nobody in the GRASS GIS or QGIS community who is willingly to > take responsibility and time to maintain, update and extend it, it > will be unusable in the future or it will depend on an obsolete or > buggy GRASS GIS version. You are right that it is easy to run out of manpower for maintenance. The framework itself will not require a lot of maintenance once implemented, a bigger problem might be with outdated adapters for libraries. Sometimes a new soul arrives willing to fix some bugs, sometimes the code is left for extinction. > I am absolutely not against a cool abstract process framework in QGIS, > but i would like to bring some IMHO important considerations into > discussion. We are indeed happy that you have joined the discussion! Regards Martin _______________________________________________ Qgis-developer mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/qgis-developer
