uptade overview

docs/source/overview.rst

@@ -7,8 +7,6 @@ Overview
     :local:
     :depth: 2
 
-.. todo:: The Birdhouse Overview needs to be updated.
-
 
 .. _introduction:
 
@@ -33,6 +31,16 @@ What is WPS?
 **Geographic Information Processing for the Web**
     *The Web Processing Service (WPS) offers a simple web-based method of finding, accessing, and using all kinds of calculations and models*.
 
+A WPS is a technical solution (WPS Concepts) in which processes are hosted on a server and accessed over the web (Fig. 1). These processes con-
+form to a standardized format, ensuring that they follow the principle of reusable design: they can be instantiated multiple times for different input
+arguments or data sources, customized following the same structure to handle new inputs, and are modular, hence can be combined to form new processes.
+In addition, a WPS can be installed close to the data to enable processing directly out of the archive. A WPS can also be linked to a theoretically limit-
+less combination of several other WPSs, or generally OpenGIS Web Services (OWS).
+Our understanding of process is used in the same sense as in the OGC standard: ’for any algorithm, calculation or model that either generates new data or trans-
+forms some input data into output data’. A submitted process is a job. A service provides a collection of processes containing scientific methods
+that focus on climate impact and extreme weather events. A combination of processes is called a workflow, and a collection of WPS-related software
+compartments is a framework. WPS divides the operation into server and client side, with appropriate security in between to avoid misuse.
+
 .. image:: _images/WPS_principe.png
 
 .. note:: Read the documentation on `Geographic Information Processing for the Web <http://geoprocessing.info/wpsdoc/>`_
@@ -41,6 +49,7 @@ What is WPS?
 
 WPS Use Case
 -----------
+.. todo:: needs to be updated.
 
 A user runs WPS processes *remotely* on a machine with direct access to climate data archives.