What is the Web Processing Service?
"The WPS standard defines an interface that facilitates the publishing of geospatial processes and makes it easier to write software clients that can discover and bind to those processes. Processes include any algorithm, calculation or model that operates on spatially referenced raster or vector data. Publishing means making available machine-readable binding information as well as human-readable metadata that allows service discovery and use.
A WPS can be used to define calculations as simple as subtracting one set of spatially referenced data from another (e.g., determining the difference in influenza cases between two different seasons), or as complicated as a hydrological model. The data required by the WPS can be delivered across a network or it can be made available at the server. This interface specification provides mechanisms to identify the spatially referenced data required by the calculation, initiate the calculation, and manage the output from the calculation so that the client can access it.
The OGC's WPS standard will play an important role in automating workflows that involve geospatial data and geoprocessing services." Quoted from the OGC Web Site
The WPS in APOLLO is the interoperable Web Service that is exposed by the server for client applications to self describe, publish and execute Geoprocesses. At a higher level, the WPS is integrated into a web based Geoprocessing workflow where end users can execute extremely powerful WPS processes through a web client "on demand".
Highlighting the consumer users use case, they will be able to navigate to anywhere in the map, discover the WPS Processes they have been provided the security right to execute, select the process, discover the PROPER data to execute the process and "on the fly" execute and receive output "data" that can be immediately mapped and downloaded after the WPS process has been completed.
The WPS in APOLLO is EXTREMELY powerful because we have enabled the IMAGINE Spatial Modeler Engine within the WPS process execution framework! So what does that mean...
In short, Analyst actors in the system will be capable of graphically designing complex spatial models and algorithms in the IMAGINE Spatial Modeler to create chained spatial model workflows and publish these workflows to the APOLLO WPS for execution for consumer end users!!! This means that a single WPS process bundles a full geoprocessing model (i.e. hydrologic models, change detection models, terrain analysis and portrayal, any gridded data processing model in fact), not just a simple mathmatical or pixel process!
We've added many "bells and whistles" to integrate the MASSIVE catalog of data that exists in the APOLLO and make it VERY EASY for end users to know what data "loads" a WPS process. During the Publishing Workflow of a model from IMAGINE, the analyst user stores for each model input a CSW query against the catalog to provide for the end user a "list" of valid data that exists within the catalog that satisfies the model input requirements (i.e. is a Multispectral image with NIR and Red band or is Terrain of > 10 meter resolution, etc, etc). The web client executes these CSW queries (along with a spatial domain query based on where the user is in the map) to display a list of valid inputs for wherever the end user is looking at the map!!
Compiling the extreme power and ease of CREATING complex geoprocesses in the Spatial Modeler, with the interoperable web service for executing these processes, with the EASE of the user experience to execute these processes by a 'non remote sensing' web client user and you have a secure, CONSUMER based geoprocessing platform over the web!
Get ready for my WPS demonstrations coming soon!!! It's going to blow your socks off!