Eigener Prozess in Python
*************************
http://pywps.wald.intevation.org/documentation/process.html

Prozess ist einer Python-Klasse mit zwei Methoden:

:meth:`__init__`
    Initialization
:meth:`execute`
    Eigener Aufruf

.. highlight:: python
   :linenothreshold: 5

**exampleBufferProcess**::

    from pywps.Process.Process import WPSProcess

    class Process(WPSProcess):
        """Main process class"""
        def __init__(self):
            """Process initialization"""

            # init process
            WPSProcess.__init__(self,
                identifier = "exampleBufferProcess",
                title="Buffer",
                version = "0.2",
                storeSupported = "true",
                statusSupported = "true",
                abstract="Create a buffer around an input vector file",
                grassLocation = True)

            # process inputs

            # complex input
            self.dataIn = self.addComplexInput(identifier="data",
                                title = "Input data",
                                # some optional parameters
                                abstract="Input data in GML format", # default is empty
                                metadata=[{"foo":"bar"}], # default is empty
                                formats=[{"mimeType":"text/xml"}], # default value
                                maxOccurs=1, # default value
                                maxmegabites="5") # default maximum size

            # string input
            self.widthIn = self.addLiteralInput(identifier = "width",
                                title = "Width",abstract="buffer width",
                                maxOccurs=3)

            # bbox input
            self.bboxIn = self.addBBoxInput(identifier = "bbox",
                                title = "Bounding box for buffering",minOccurs=0)

            # process outputs    

            # complex output
            self.bufferOut = self.addComplexOutput(identifier="buffer",
                                    title="Output buffer file")

            # literal output
            self.textOut = self.addLiteralOutput(identifier="text",
                                    title="Just some literal output")

            # bbox output
            self.bboxOut = self.addBBoxOutput(identifier="bbox",
                                    title="Resulting bbox")
            
        def execute(self):
            """Execute process.
            
            Each command will be executed and output values will be set
            """

            # run some command from the command line
            self.cmd(["g.region","-d"])

            # import data
            self.status.set("Importing data",20)
            out = self.cmd(["v.in.ogr","-o","dsn=%s" % (self.getInputValue('data')),"output=data"])
            self.cmd(["g.region","vect=data"])

            # buffer
            self.status.set("Buffering",50)
            self.cmd(["v.buffer","input=data","output=data_buff","distance=%s"%self.widthIn.getValue()[0],
                    "scale=1.0","tolerance=0.01"])

            # vector -> raster
            self.status.set("Vector to raster conversion",70)
            if self.bboxIn.minx == None:
                self.cmd(["g.region","vect=data_buff"])
            else:
                self.cmd(["g.region",
                    "e=%s" % self.bboxIn.minx,
                    "s=%s" % self.bboxIn.miny,
                    "w=%s" % self.bboxIn.maxx,
                    "n=%s" % self.bboxIn.maxx])
            self.cmd(["v.to.rast","use=cat","input=data_buff","output=buff","type=area"]) 

            # export
            self.status.set("Exporting data",90)
            self.cmd(["v.out.ogr","type=area","format=GML","input=data_buff","dsn=out.xml","olayer=path.xml"])

            north = south = east = west = 0
            for l in self.cmd(["v.info","-g","data_buff"]).split("\n"):
                coord=l.split("=")
                if coord[0] == "north":
                    north = coord[1]
                elif coord[0] == "west":
                    west = coord[1]
                elif coord[0] == "east":
                    east = coord[1]
                elif coord[0] == "south":
                    south = coord[1]

            self.bboxOut.setValue([west,south,east,north])

            # setting output values
            self.bufferOut.setValue("out.xml")
            self.textOut.setValue("hallo, world")