Process Inputs and Outputs

Process inputs and outputs are of three types:

Usually used for raster or vector data
Used for simple text strings
Two coordinate pairs of lower-left and upper-right corners in defined coordinate sytem.

Inputs and outputs should usually be defined in the __init__ method of the process.

ComplexValue input and Output

ComplexValue inputs and outputs are used in WPS to send larger sets of data (usually raster or vector data) into the process or from the process back to the user. The pywps.Process.WPSProcess.addComplexInput() method returns an instance of pywps.Process.InAndOutputs.ComplexInput for inputs. For outputs, they are called with pywps.Process.WPSProcess.addComplexOutput(), which returns pywps.Process.InAndOutputs.ComplexOutput.

The pywps.Process.InAndOutputs.ComplexInput.value and pywps.Process.InAndOutputs.ComplexOutput.value attributes contain the file name of the raster or vector file.

For inputs, consider using the pywps.Process.InAndOutputs.ComplexInput.getValue() method, for getting the value of the input, which can be returned as file object or file name.

For outputs, you should definitely use the pywps.Process.InAndOutputs.ComplexOutput.setValue() method for setting the results file name. The method accepts a file object as well as a file name.

Sometimes, users are sending the data as reference to some URL (e.g. OGC WFS or WCS service). PyWPS downloads the data for you and stores them to a local file. If the client requires reference to the output data, PyWPS will create this for you. PyWPS is able to setup a MapServer instance for you, and return OGC WFS or WCS URLs back to the client. For more on this topic, see using-mapserver.

Even you can (and should) define support data mimetypes (pywps.Process.InAndOutputs.ComplexInput.formats), mimetype only is checked. PyWPS does not care about valid schemas or anything else. This should be handled by Your process.

Vector data values

Vectors are usually handled as GML files. You can send any other file format as well, such as GeoJSON, KML or any other vector data. Only condition is: the file should be in text form (so it can fit into XML correctly), if you want to append it as part of the input XML request and everything should be stored in one file.

Vectors are the default pywps.Process.InAndOutputs.ComplexInput.format of ComplexValue input or output – text/xml (GML) is expected.


Some users do want to send ESRI Shapfiles. This is in general not to advisable. Shapefiles are a binary format, which is hard to be used with XML, and it consists out of at least three files shp, shx and dbf.

If you still want to handle shapefiles, you have either to zip everything in one file or define three separate complex inputs.

Example of simple input vector data:

self.inputVector = self.addComplexOutput(identifier="in",title="Input file")

Example of more complex input vector data:

self.gmlOrSimilarIn = self.addComplexInput(identifier="input",
                        title="Input file",
                        abstract="Input vector file, usually in GML format",
                        formats = [
                                    # gml
                                    {mimeType: 'text/xml',
                                    # json
                                    {mimeType: 'text/plain',
                                    encoding: 'iso-8859-2',
                                    schema: None

                                    # kml
                                    {mimeType: 'text/xml',
                                    encoding: 'windows-1250',
                                    schema: ''}
                        # we need at least TWO input files, maximal 5
                        minOccurs: 2,
                        maxOccurs: 5,
                        metadata: {'foo':'bar','spam':'eggs'}

Raster data values

Sometimes, you need to work with raster data. You have to set the proper pywps.Process.InAndOutputs.ComplexInput.formats attribute of supported raster file format. Since rasters are usually in binary format, you would usually have to send the data always as reference. Fortunately, this is not the case. PyWPS can handle the input data, encoded in Base64 format and once PyWPS needs to send raster data out as part of Execute response XML, they are encoded with Base64 as well.

Example of simple output raster data:

self.dataIn = self.addComplexOutput(identifier="raster",
                    title="Raster out",

LiteralValue input and Output

With literal input, you can obtain or send any type of character string. You will obtain an instance of pywps.Process.InAndOutputs.LiteralInput or pywps.Process.InAndOutputs.LiteralOutput.

Literal value Inputs can be more complex. You can define a list of allowed values, type of the literal input, spacing and so on.


Spacing is not supported, so you can not currently define the step in allowed values row.


For type settings, you can either use the types module, or the Python type() function. The default type is type(0) – Integer. PyWPS will check if the input value type matches allowed type.


If you need the String type of literal input, PyWPS will always remove everything behind “#”, “;”, “!”, “&” and similar characters. Try to avoid usage of LiteralValue input directly as input for e.g. SQL database or command line programs. This could cause a serious system compromise.

Allowed Values

PyWPS lets you define a list of allowed input values. These can be string, integer or float types. Default values are defined in the list. Ranges are defined as two-items filed in form of (minimum,maximum). For example, we would like to allow values 1,2,3, 5 to 7, and ‘spam’, the pywps.Process.InAndOutputs.LiteralInput.values value would look like:


Default is “*”, which means all values.

Simple example of LiteralValue output:

self.widthOut = self.addLiteralOutput(identifier = "width",
                     title = "Width")

Complex example of LiteralValue input:

self.litIn = self.addLiteralInput(identifier = "eggs",
                title = "Eggs",
                abstract = "Eggs with spam and sausages",
                minOccurs = 0,
                maxOccurs = 1,
                uoms = "m",

BoundingBoxValue input and Output

BoundingBox are two pairs of coordinates, defined in some coordinate system (2D or 3D). In PyWPS, they are defined in pywps.Process.InAndOutputs.BoundingBoxInput and pywps.Process.InAndOutputs.BoundingBoxOutput. For getting them, use pywps.Process.WPSProcess.addBBoxInput() and pywps.Process.WPSProcess.addBBoxOutput() respectively.

The value is a list of four coordinates in (minx, miny, maxx, maxy) format.

Example of BoundingBoxValue input:

self.bbox = self.addBBoxOutput(identifier = "bbox",
                          title = "BBox")