pywps a tutorial for beginners and developers
TRANSCRIPT
PyWPS a tutorial for beginners and developers
Jorge de Jesus (Plymouth Marine Laboratory)Luca Casagrande (Universit degli Studi di Perugia) Jachym epicky (Help Service Remote Sensing Company)
Before starting
Please put your OSGEO livecd or usb-stick inside your laptop and start your machine.
Program
Introduction partWPS Standard and PyWPSNewbie partInstallation, setup and first processDevelopers partPyWPS in detail, mod_python,jython, GRASSGalleryExamples of applications using PyWPS
Introduction Section
Install the tutorial
Open Firefox and download the script from the pyWPS main page:http://pywps.wald.intevation.org/Make it executable (password is user):sudo chmod +x install_pywps_svn.shStart the script:sudo ./install_pywps_svn.shYou can edit files using nano, but remember to always use sudo (password is user).
Definitions
Web Processing Service (WPS) is an OGC standard protocol to make GIS calculation available to the internet
Open Geospatial Consortium (OGC) is a non-profit, international, voluntary consensus standards organization that is leading the development of standard for geospatial and location based service.
WPS standard
... provides rules for standardizing how inputs and outputs (requests and responses) for geospatial processing services, such as polygon overlay. The standard also defines how a client can request the execution of a process, and how the output from the process is handled..
Invoking WPS server
HTTP GET method with key-value-pairs encoded request (KVP)
HTTP POST method, using XML format of the request
SOAP
For this tutorial we will use just the HTTP GET method
Key Value Pairs request
http://localhost/cgi-bin/wps.py?service=WPS&request=GetCapabilities
http://localhost/cgi-bin/wps.py Is the server addressThe ? sign indicates, that the request parameters will startservice=WPS&request=GetCapabilitiesThe KVP-encoded request. We send two request parameters to the server:service - which we set to WPSrequest - which is set to GetCapabilities
XML Request
In this case, the request is encoded in XML form and send to the server directly via HTTP POST (the WPS server will read the file from standard input directly).
1.0.0
WPS operations
GetCapabilities: returns service-level metadata
DescribeProcess: returns a description a process including its inputs and outputs
Execute: returns the output(s) of a processDespite the specification that requests should be case insensitive, it is recommended to use the upper camel case standard in all sorts of WPS operation requests
GetCapabilities
Mandatory parameters:service,requestThe server returns basic Capabilities document. Among others it contains:ServiceIdentification
Service provider (Name, Organization, Address, ...)
ProcessOfferings - List of available processes
http://apps.esdi-humboldt.cz/pywps/?service=WPS&request=GetCapabilities
DescribeProcess
Mandatory parameters:version, name of the process or all keywordThe ProcessDescriptions document contains detailed description of selected processes. Each process is identified by:Title
Identifier
DataInputs
DataOutputs
http://apps.esdi-humboldt.cz/pywps/?service=WPS&version=1.0.0&request=DescribeProcess&identifier=all
Execute
Mandatory parameters:No mandatory parameters
http://apps.esdi-humboldt.cz/pywps/?service=WPS&version=1.0.0&request=Execute&identifier=literalprocess&datainputs=[int=1;float=3.2;zeroset=0;string=spam]
KVP inputs encoding
A semicolon (;) shall be used to separate one input from the next
An equal sign (=) shall be used to separate an input name from its value and attributes, and an attribute name from its value
An at symbol (@) shall be used to separate an input value from its attributes and one attribute from another.
All field values and attribute values shall be encoded using the standard Internet practice for encoding URLs
PyWPS also supports the use of [ ] to group the datainputs as follows: datainputs=[int=1;float=3.2]
Description of Data Inputs and Outputs
Three types of inputs and outputs are defined in the OGC standard. LiteralData, ComplexData and BoundingBox data.
LiteralData
LiteralData can be any character string, float,date, etc normally described as Primitive datatype in the W3C XML
WPS standard also allows the use of UOM (Unit of Measures), default values and AllowedValues.
ComplexData
Complex Data data type is used for pasting complex - Vector- Raster- or other data to the server or obtain it as result of the process. There are two ways, how this complex data are handled:Either you send them directly as part of the request to the server or you obtain them as part of the XML response from the server.
Or you send or obtain just reference to the data URL to the file or service, where the data can be downloaded.
Bounding Box Data
It is used to describe some sort of bounding box area . The input description must state: the default coordinate reference system (CRS) used
other CRS supported
&bboxInput=71.63,41.75,-70.78,42.90,urn:ogc:def:crs:EPSG:6.6:4326,2
PyWPS
pyWPS is:A framework for the implementation of WPS 1.0.0
Totally written in python 2.6
Organized into packages and classes for easy maintenance
Open to new developments and functionalities that can be integrated in WPS 1.0.0
Is run from bash or as a cgi process
pyWPS is not:Is not an analytical tool or engine. It does not perform any type of geospatial calculation
Is not a XML parser or generator. It does not validate the GMLs against given schemas (yet), it does not build GML from Python objects
Can't be used to build general web applications like CherryPy framework
PyWPS
PyWPS history
2006First pyWPS 1.0.0 release, a project was born
First presentation held at FOSS4G 2006 Lausanne: "GRASS goes web: pyWPS"
2007pyWPS 2.0.0 gets release, supporting WPS 0.4.0
PyWPS history
2008pyWPS 3.0.0 gets release:Support for WPS 1.0.0
New simple configuration files
Support for multiple WPS servers with one pyWPS Installation
Support for internationalization
Simple code structure
New examples of processes
PyWPS history
2009pyWPS 3.1.0 gets released with new featuresUp-to-date examples
New generic WPS JavaScript library
Multiple fixes in both, source code and templates
New style In- and Outputs Complex object
Tons of bugs fixed
PyWPS history
2010pyWPS is recomended as THE WPS tool in GIGAS project ( GEOSS, INSPIRE and GMES an Action in Support). As explained in the "GIGAS Technology Watch Report WPS"
"PyWPS Web Processing Service: is a Python program which implements the OGC WPS 1.0.0 standard (with a few omissions). PyWPS was chosen as it is up to date with the WPS standard and has a low footprint, making it easy to install on most Linux systems.
Newbies Section
Installation
Configuration file
PyWPS instance / Wrapper Script
First process
Installation Requirements:
python currently 2.5, 2.6python xml packagehtmltmpl engine older versions
For cool stuff you may need:
GRASS-GIS
Install files can be found in:
http://pywps.wald.intevation.org/download/SVN access to the latest code:
svn checkout https://svn.wald.intevation.org/svn/pywps/trunkLatest package:
http://wald.intevation.org/frs/download.php/589/pywps-3.1.0.tar.gz
Clean install:
> tar -xvzf /tmp/pywps-VERSION.tar.gz> cd pywsp-VERSION> python setup.py installThere's DEB and RPM packages. Badly maintain :(
Testing the script by running the wps.py (/usr/bin) script
> /usr/bin/wps.pyIf everything is ok....
PyWPS NoApplicableCode: Locator: None; Value: No query string found.Content-type: text/xml
No query string found.
Configuration file for PyWPS can be located on several places.
There are global and local PyWPS configuration files.
Local files overwrite the global one
Global:
/etc/pywps.cfg/usr/local/pywps-VERSION/etc/pywps.cfgAny path defined in thePYWPS_CFG environment variableLocal:
pywps.cfg is a Key = Value text file
4 sections are present in the file:
[wps][provide][server][grass]Remember: The file is case-sensitive
[wps]titleversionabstractfeeskeywordslang
Baisic meta information necessary to populate the WPS doc.
Other variables aren't shown in this example
Server configuration options, path locations and URL translation and service limits
[server]maxoperationsmaxinputparamlengthmaxfilesizeoutputUrloutputPathprocessesPath
Other variables aren't shown in this example
Most important: outputURL, outputPath, processPath
outputURL:
URL that will be used to point to the WPS outputs
outputPath:
Folder where PyWPS will drop the outputs (server accessible)
http://localhost/wpsoutputhttp://rsg.pml.ac.uk/wps/wpsoutput/var/www/html/wpsoutput/usr/local/apache/htdocs/wps/wpsoutput/var/www/html/wpsoutput/var/www/html/wpsoutput
processPath:
Folder path with stored processes
/usr/local/pywps/processes/usr/local/pywps/processes/usr/local/pywps/processes/usr/local/pywps/processes/usr/local/pywps/processes/home/user/processesIt's important that these 3 parameters are properly configured
PyWPS can be installed once in a server,
but it may be configured to run several WPS services (instances).
WPS instanceProcess folderpywps.cfg file
1) Setup a process folder
2) copy configuration file-template and edit it to desired configuration
> mkdir -p /usr/local/wps/processes> cp pywps-VERSION/pywps/default.cfg /usr/local/wps/pywps.cfg> nano /usr/local/wps/pywps.cfg3) We need to populate the process directory
> cp pywps-VERSION/examples/ultimatequestionprocess.py /usr/local/wps/processes/
4) Every process in the process folder needs to be registered in a file called __init__.py
> cd /usr/local/wps/processes/> echo "__all__=['ultimatequestionprocess']" > __init__.py__all__ it's a python array will the processe list
We've done 50% of an instance :)
A WPS instance is just a script that alters some parameters before calling wps.py
#!/bin/sh # Author: Jachym Cepicky# Purpose: CGI script for wrapping PyWPS script# Licence: GNU/GPL# Usage: Put this script to your web server cgi-bin directory, e.g.# /usr/lib/cgi-bin/ and make it executable (chmod 755 pywps.cgi) # NOTE: tested on linux/apache export PYWPS_CFG=/usr/local/wps/pywps.cfgexport PYWPS_PROCESSES=/usr/local/wps/processes/ /usr/local/pywps-VERSION/wps.py $1wps.cgi file
We need to configure PYWPS_CFG and PYWPS_CFG to specify the instance
We can copy the wrapper script to Apache's cgi-bin folder
> cp wps.cgi /usr/lib/cgi-binAssuming that Apache is configure to support script execution...
http://localhost/cgi-bin/pywps.cgi?request=DescribeProcess&service=WPS&version=1.0.0&process=ultimatequestionprocess
ultimatequestionprocess Answer to Life, the Universe and Everything .... answer The numerical answer to Life, Universe and Everything integer
POSTGETSOAP
GetCapabilitiesDescribeProcessExecute12
1Load ProcessCheckPropertiesWPS output
2Load ProcessgetInputrunsetOuputWPS output
PyWPS's assemble factory approach
User's process
Process as an extended class of WPSProcess with method run() that will execute the code
WPSProcess classProcess1Process2ProcessN
All processes have the following skeleton:
from pywps.Process.Process import WPSProcess class Process(WPSProcess): def __init__(self): # init process WPSProcess.__init__(self, < Process's information like: identifier, title, status >) < Inclusion of inputs and outputs to process class > def execute(self):< code >WPSProcess class provides extra functionalities like:- Command line util: self.cmd()- Status setting: self.status.set(message,percentage)
Process's attributes:
class Process(WPSProcess): def __init__(self): # init process WPSProcess.__init__(self,identifier=firstprocess, #same file name title=foo, abstract=bacon and eggs,version = "0.1", storeSupported = "true", statusSupported = "true", )The only mandatory attribute is: identifier
LiteralDataComplexDataBBOX3 types of Input/Output defined in WPS:
Each Input/Output is a method of WPSProcess class
Each Input/Output is created when class in initiated
LiteralDataComplexDataBBOXself.addLiteralInput(...)self.addLiteralOutput(...)self.addComplexInput(...)self.addComplexOutput(...)self.addBBoxInput(...)self.addBBoxOutput(...)
Each self.add*() defines/creates an input. The class constructor accepts the WPS parameters:
self.Input1 = self.addLiteralInput(identifier = "input1",title = "Input1 number",abstract=foo,minOccurs=1, type=types.IntType default="100")Only identifier and title are mandatory
A more Complex example
self.dataIn = self.addComplexInput(identifier="data", title="Input vector data",abstract=foo formats = [{'mimeType':'text/xml'}])
Only identifier and title are mandatory
What about outputs
Identical syntax and procedure :)
self.dataOut = self.addComplexOutput(identifier="output", title="Output vector data", formats = [{'mimeType':'text/xml'}])
self.Output1 = self.addLiteralOutput(identifier="output1", title="foo")
The add*Input and add*Output are set in the beginning of the class (__init__ method):
from pywps.Process.Process import WPSProcess class Process(WPSProcess): def __init__(self): # init process WPSProcess.__init__(self, < Process's information like: identifier, title, status >) self.Input1=self.addLiteralInput(identifier=input1) self.dataOut =self.addComplexInput(identifier=outputs) def execute(self):< code >
OK we have WPS inputs and output, how can I get them ?!?!?!
Using the JAVA get and set philosophy :)
Each Input has a getValue() method
Each Output has a setValue() method
This is done inside the execute method()
from pywps.Process.Process import WPSProcess class Process(WPSProcess): def __init__(self): # init process WPSProcess.__init__(self, < Process's information like: identifier, title, status >) self.Input1=self.addLiteralInput(identifier=input1) self.dataOut =self.addComplexInput(identifier=outputs) def execute(self):input1=self.Input1.getValue()XMLdata=foo self.dataOut.setValue(XMLData) #input or file objectPlease check wiki !!!!
http://pywps.wikispaces.com/InputOutput
Fist Process, a returner process
from pywps.Process import WPSProcess class Process(WPSProcess): def __init__(self): ## # Process initialization WPSProcess.__init__(self, identifier = "returner", title="Return process", abstract="""This is demonstration process of PyWPS, returns the same file, it gets on input, as the output.""", version = "1.0", storeSupported = "true", statusSupported = "true")Process class initiation, identifier, WPS status and storeExecuteResponse definition
## # Adding process inputs self.dataIn = self.addComplexInput(identifier="data", title="Input vector data", formats = [{'mimeType':'text/xml'}])
self.textIn = self.addLiteralInput(identifier="text", title = "Some width")Attention to indent !!! It's python !!!!
## # Adding process outputs
self.dataOut = self.addComplexOutput(identifier="output", title="Output vector data", formats = [{'mimeType':'text/xml'}])
self.textOut = self.addLiteralOutput(identifier = "text", title="Output literal data") ## # Adding process inputs self.dataIn = self.addComplexInput(identifier="data", title="Input vector data", formats = [{'mimeType':'text/xml'}])
self.textIn = self.addLiteralInput(identifier="text", title = "Some width")
def execute(self):
# just copy the input values to output values self.dataOut.setValue( self.dataIn.getValue() ) self.textOut.setValue( self.textIn.getValue() )
returnHopefully this will work:
http://localhost/python/wps.py?request=Execute&service=WPS&identifier=returner&Version=1.0.0&datainputs=[text=abc;data=foo]
Developers Section
Hacking ( wps.py code for dummies)
Logging (and wood)
GRASS (after the wood)
Mod_Python (Pythons and Horses)
Tomcat server (Pythons and Cats)
Mapserver support (More OGC stuff)
OpenLayers (Let there be layers.....)
SOAP/WSDL (Beatiful soap... so they say...)
PyCallGraph (The all enchilada!!!)
PyWPS's wps.py has the following pseudo-code structure:
Start wps.py:1. Determine request_method (GET or POST)2. if no input: raise Exception and exit3. try: initiate PyWPS class according to request_method parse Request do Request get Response and make proper reply4. exception: reply Error response
Some Hacking experiments:
Exit if request is POST (around line 95):
if method==pywps.METHOD_POST: sys.exit(1)Encript a WPS response:
if response: pywps.response.response(response, sys.stdout,wps.parser.soapVersion,wps.parser.isSoap, wps.request.contentType)if response: response=xor_crypt_string(response,key="FOSS4G") pywps.response.response(response,.....
In PyWPS you can use the logging module anywhere in the code.
import logginglogging.debug("Something has been debugged")pywps.cfg file contains the path to the log file
debug=true # deprecated since 3.2, use logLevel insteadlogFile=/etc/httpd/logs/pywps.loglogLevel=DEBUGThen the file log will contain a line, like this:
PyWPS [2010-08-25 17:39:00,499] DEBUG: Something has been debugged
Eclipse IDE is the default debugging platform using PyDEV tools
Code to be debugged should contain a path to the PyDEV tools:
sys.path.append("..plugins/org.python.pydev.debug_1.6.0.2010071813/pysrc/")After this path append, it is possible to import pydev module
import pydevdNow the code with pydevd is enabled for debbuging
Next step is to activate the debug server that will listen to the script.
Now everytime that the python interperter finds:
pydevd.settrace('localhost', port=5678, stdoutToServer=True, stderrToServer=True)It will stop and send the variable to debug server
From eclipse it will be possible to continue or stop the script
The code was launched from Apache using a GetCapabilities request
PyWPS doesn't come with out-of-the-box tools
PyPWS is Python, so connect, connect, connect !!!!! To GRASS GIS
You may work with a predefined grassLocation or a temporary one
WPSProcess.__init__(self, identifier = "foo", ... grassLocation = True)Temporary grassLocation
XY coordinate system
WPSProcess.__init__(self, identifier = "foo", ... grassLocation = spearfish60)Permanent grassLocation
Previous defined coordinate system
gisdbase base path specified in configuration file (pywps.cfg)
Absolute path in grassLocation
OR
Commands passed as an array with command + arguments:
self.cmd(["r.los","in=elevation.dem","out=los","coord=1000,1000"]) self.cmd(["d.mon","start=PNG"],stdout=False)Inside the execute method()self.cmd() is a WPSProcess class method
It's not a simple Python bash command util
A total Pythonic way to connect to GRASS!!!!!!
from grass.script import core as grassdef execute(self): ret=grass.run_command("d.his", h_map="drap_map", i_map="relief_map", brighten=0) return
Command line strategy
grass.mapcalc("MASK=if(($cloudResampName < 0.01000),1,null())", cloudResampName = cloudResampName)
Package access strategy
"Mod_python is an Apache module that embeds the Python interpreter within the server.
In: http://www.modpython.org/
version 3.2 provides a wps.py script designed to be integrated into mod_python
https://svn.wald.intevation.org/svn/pywps/trunk/webservices/mod_python/wps.pySo what is the advantage ?! SPEED !!!!!
50x faster on request processing
Integration with Apache's API
Ability to handle request phases, filters and connections
Default httpd.conf for PyWPS:
AddHandler mod_python .py Options Indexes FollowSymLinks AllowOverride None Order allow,deny Allow from all PythonHandler wps PythonDebug On PythonAutoReload On PythonOption PYWPS_PROCESSES /../python2.6/site-packages/pywps/processes PythonOption PYWPS_CFG /etc/pywps.cfg
Inform Apache that wps is the default handler of any request
Pass env variables PYWPS_PROCESSES and PYWPS_CFG
Mod_python can be used to restrict access to the WPS:
: PythonHandler wps PythonAuthenHandler wps : AuthType Basic AuthName "Restricted Area" require valid-user
PythonAuthenHandler wps
def authenhandler(req):
pw=req.get_basic_auth_pw() user=req.user
if (user=="bacon" and pw=="eggs"): return apache.OK else: return apache.HTTP_UNAUTHORIZED
Function added to wps.py
apache.OK continue wps.pyUNAUTHORIZED Stop wps.py
mod_python can apply filters on HTTP request/response
The filter needs to be register to Apache and mod_python
PythonOutputFilter wps ENCRPYTAddOutputFilter ENCRYPT .pydef outputfilter(filter): req=filter.req #getting requirement s = filter.read() #You have always to read and then write the filter (no matter what) if req.status == apache.HTTP_OK: s_crpyt=xor_crypt_string(s, "FOSS4G") filter.write(s_crpyt) else: filter.write(s) filter.close() #Always close the stream otherwise it will write twiceThe filter is applied to any WPS output, encrypting the response
WPS client/server 'secured' interaction
The server provides getCapabilities and describeProcess to anyone.
The execute is permitted only to authorized users
Note: the base authentication credentials are used to allow the geo web service to receive delegation (downloading a proxy certificate) from another web service .The authentication/authorization of the execute is managed through X.509 certificates which are handled through the GridSite module for Apache (http://www.gridsite.org/).
Who is using mod_python and PyWPS ?!
GENESI-DR, (Ground European Network for Earth Science Interoperations - Digital Repositories),www.genesi-dr.eu & www.genesi-dec.eu
INFRA-2007-1.2.1 : Scientific Digital Repositories
Python Code
Jython Compiler
Java ByteCode
TomCat Instance
No Voodoo , Just computer science !!!!
PywpsServlet.pyInstead of wps.py we have a new script called PywpsServelet.py
JAVA Servelet structure
def doGet(self,request,response):: def doPost(self,request,response)::def doWPS(self,request,response)
class PywpsServlet(HttpServlet):
https://svn.wald.intevation.org/svn/pywps/trunk/webservices/tomcat/WEB-INFPywpsServlet.py
Configuration file used by TomCat
The twin brother or wps.py
- All PyWPS code needs to be copied to the Tomcat folder running the instance:
> cd apache-tomcat-6.0.29/wps> mkdir wps> mkdir wps/WEB-INF> mkdir wps/lib> mkdir wps/WEB-INF> mkdir wps/lib> cp $PYWPS_SOURCE/webservices/tomcat/web.xml wps/WEB-INF/> cp -r $PYWPS_SOURCE/pywps wps/
Now we just need the Jython Library :)
> cp jythonlib.jar $CATALINA_HOME/webapps/wps/lib/
And we have just the last piece of the puzzle missing...
> cp $PYWPS_SOURCE/webservices/tomcat/PywpsServlet.py
What about PYWPS_PROCESSES ?!
import osos.environ["PYWPS_PROCESSES"] = "/path/to/processes"Inside PywpsServlet.py
- After start/stop of tomcat we should be able to make a request:
http://localhost:8080/wps/PywpsServlet?service=wps&request=getcapabilities
Still in the SVN tree, highly experimental !!!!!
Who's using it ?! ...or will be using.....
Its intended to be the default WPS service for Conceptual Schema Transformer
Yes, PyWPS even supports Mapserver :)
Still experimental in the SVN.....
ComplexData output@asReference=TrueComplexData reference link outputed as a OGC service
http://foo/bar/cg-bin/mapserv?map=/outputs/output-123.map&service=WCS&request=GetCoverage&....
According to the data type the link will point to a WMS, WFS or WCS service.
So how is it set ?!
self.imageOut=self.addComplexOutput (identifier="tiffOut", title="GeotTiff result", useMapscript=True formats = [ {"mimeType":"image/tiff"}, {"mimeType":"image/png"}])
userMapscript=True
mimeType
image/tiff == WCSimage/png == WMS
text/xml == WFS
In the SVN tree we have a WPS client specific for Openlayers
https://svn.wald.intevation.org/svn/pywps/trunk/webclient/WPS.jsJust append the file to the HTML's script tags
Now a OpenLayers.WPS class should be available
WPS+describeProcess()+getCapabilities()+execute()+onDescrivedProcess: callback+onGotCapabilities: callback+onExecuted: callbackWe have 2 major classes, WPS and process
WPS API will make all the requests,
parse the result and when finish will run a call back function
A simple example:
wps = new OpenLayers.WPS(url, {onGotCapabilities: onGetCapabilities});wps.getCapabilities();function onGetCapabilities() { : var capabilities = ""+wps.title+""; capabilities += "Abstract"+wps.abstract;: document.getElementById("wps-result").innerHTML = capabilities; };Please check wiki for an extensive explanation !!!!
http://pywps.wikispaces.com/OpenLayers
SOAP == Simple Object Access Protocol
WSDL == Web Services Description Language
OGC defines that WPS 1.0.0 should support these standards
PyWPS has some support for SOAP
PyWPS generates a simple WSDL file
SOAP is a messaging framework, meaning, a structured way to pass, explain and process a message.
XML content (message)SOAP functionalities (authentification, actors etc)
XML wrapper defining SOAP
Example:
1.0.0
- Currently PyWPS will accept SOAP XML requests
- BUT it will not process any header content or special Execute tags
- WSDL is a XML document describes a Web service.
-Considering a WPS process, then a WSDL would some something like:
WSDL Doc == GetCapabilites+ DescribeProcess+ Execute+ OGC WPS standard definition (schema)
Redundancy !!!
Data type Message defined by dataType Operations and messages SOAP, HTTP POST etc "http://localhost/wps.py"
http://pywps.wikispaces.com/WSDL
WSDL file is served as follows:
http://foo/wps.py?WSDL
File location:pywps.cfg
http://foo/wps.py/ultimatequestionprocess?WSDLNo specific process WSDL file request or support :(
SVN branch pywps-3.2-SOAP for WSDL and SOAP development
Next PyWPS release will have better SOAP/WSDL support
WPS 2.0.0 to have better SOAP/WSDL support
Million dolar question ?! Why do we need SOAP/WSDL
- Orchestration and interaction with other web services
- Ability to use BPEL (Bussines Procedure Language) to orchestrate services
-PyCallGraph is used to generate a graphic representation of code being run
- Useful to check bottlenecks and code problems
> python wps.py "request=GetCapabilities&service=WPS"
- Major time consumption in initProcess() method.
- More processes == Slower output
A detailed analysis using pyCallGraphic has shown:
NO MAJOR BOTTLE NECKSExecute/DescribeProcess spent most of time in process handling
If PyWPS is slow, blame the process code
Minimum overhead when callingUpdate and Exception reports
Gallery / Examples
NETMAR Open Service Network for Marine Environmental Data
NETMAR aims to develop a pilot European Marine Information System (EUMIS) for searching, downloading and integrating satellite, in situ and model data from ocean and coastal areas.
Provide a user-configurable system offering flexible service discovery, access and chaining facilities using OGC, OPeNDAP and W3C standards.
Lots of WPS processes!!!Use a semantic framework coupled with ontologies for identifying and accessing distributed data, such as near-real time, forecast and historical data.
http://rsg.pml.ac.uk/wps/wps.cgi?request=Execute&service=wps&version=1.0.0&identifier=histogramprocess&datainputs=[imageInput=http://rsg.pml.ac.uk/wps/sat_image.tif]&responsedocument=histogramOutput=@asreference=true
http://rsg.pml.ac.uk/wps/wps.cgi?request=Execute&service=wps&version=1.0.0&identifier=histogramprocess&datainputs=[imageInput=http://rsg.pml.ac.uk/wps/srtm.tif]&responsedocument=histogramOutput=@asreference=true
http://rsg.pml.ac.uk/wps/wps.cgi?request=Execute&service=wps&version=1.0.0&identifier=reducer&datainputs=[reductionFactor=0.1;imageInput=http://rsg.pml.ac.uk/wps/srtm.tif]&responsedocument=imageOutput=@asreference=true&status=true&storeExecuteResponse=true
60 megas
700kb
Acknowledgments:
Simone Gentilini (JRC). GENESI-DR Project funded by FP7 program under (INFRA-2007-1.2.1) Scientific Digital Repositories www.genesi-dr.eu & www.genesi-dec.eu
Plymouth Marine Laboratory Remote Sensing Groupwww.pml.ac.uk & http://rsg.pml.ac.uk
Netmar project. Project partially funded by FP7 program under (ICT-2009.6.4) Information & Communication Technologies.http://netmar.nersc.no/
HS-RS Help Service Remote Sensing http://www.bnhelp.cz/