Use case #1 - Invoke a web service dynamically

CSISS/GMU Geobrain team has developed a client application which could dynamically call a web service. You can use it to automatically create a test client from the WSDL description for a web service. Its URL is:

http://laits.gmu.edu:8099/wscaller/wscaller.jsp

http://laits.gmu.edu:8099/wscaller/wscaller.jsp?wsdl=http://geobrain.laits.gmu.edu:801/axis/services/Grass_Raster_DataConversion?wsdl

Use case #2 - Geobrain Online Analysis System (GeOnAS)

http://geobrain.laits.gmu.edu:81/OnAS/

http://geobrain.laits.gmu.edu:81/OnAS/User_Guide.htm in htm

http://geobrain.laits.gmu.edu:81/OnAS/User_Guide.pdf in pdf

Use case #3 - Find Shortest Path

1. GetCapabilities: This operation allows a client to request and receive back service metadata (or Capabilities) documents that describe the abilities of the specific server implementation.
2. DescribeProcess: This operation allows a client to request and receive back detailed information about one or more process(es) that can be executed by an Execute operation, including the input parameters and formats, and the outputs.
3. Execute: This operation allows a client to run a specified process implemented by the WPS, using provided input parameter values and returning the outputs produced.

We can send requests to the WPS:

1. Get Capabilities request:
On this page http://geobrain.laits.gmu.edu:8099/wps/WebProcessingService?Request=GetCapabilities&Service=WPS, you could find different processes by '<'ows:Identifier'>' in '<'ProcessOfferings'>'. "edu.gmu.laits.wps.server.algorithm.ShortestPathAlgorithm" is included in it. This means our WPS service provides such process or algorithm.
2. DescribeProcess request:
The description of the process could be viewed by this link: (This is a DescribeProcess request) http://geobrain.laits.gmu.edu:8099/wps/WebProcessingService?Request=DescribeProcess&Service=WPS&Version=0.4.0&Identifier=edu.gmu.laits.wps.server.algorithm.ShortestPathAlgorithm This page describes or gives you some information about inputs and outputs of the process "edu.gmu.laits.wps.server.algorithm.ShortestPathAlgorithm". Here request one process by "Identifier=".
3. Execute post:
The shortest path algorithm (or process) could be executed by requesting an Execute operation. WPS test page URL is: http://geobrain.laits.gmu.edu:8099/wps/test_shortestpath.html. This test form was written according to WPS executes specification (wpsExecute.xsd). It corresponds to the DescribeProcess description of the process. If you want to execute it, you should specify each input values for the process.

The image of the result gml is shown at the below.

In the future, our OnAS web client could parser gml file and render it to an image, we could view the result in OnAS directly.

Use case #4 - Create a Clipping Web Service

Here we create clipping web service based on our three GRASS webservices:

1. Grass_General_Commands Service (http://geobrain.laits.gmu.edu:8099/axis/services/Grass_General)
   You can see corresponding Java interface (http://geobrain.laits.gmu.edu:8099/webservices/grass/Grass_General_Commands.java )
   We use its "create_dummy_location" method to initialize the GRASS environment: database, location and mapset
   
2. Grass_Vector_InOut_Commands Service (http://geobrain.laits.gmu.edu:8099/axis/services/Grass_Vector_InOut )
   Java interface ( http://geobrain.laits.gmu.edu:8099/webservices/grass/Grass_Vector_InOut_Commands.java)
   Use its "v_in_ogr" method to import two vector files
   Use its "v_out_ogr" method to export the result.
   
3. Grass_Vector_Commands Service (http://geobrain.laits.gmu.edu:8099/axis/services/Grass_Vector )
   Java interface ( http://geobrain.laits.gmu.edu:8099/webservices/grass/Grass_Vector_Commands.java )
   Use its "v_overlay" method to do vector clipping
   

You could find the implement code in the files Clip_Functions.java and Clip_FunctionsSoapBindingImpl.java. Note that you need to have three GRASS webservices stubs in your classpaths (see the import statements in the code, eg. "import edu.gmu.laits.ws.grass.Grass_General_Commands.*;"). You can create these stubs using WSDL2Java in Axis.

It will be an easy thing to turn the above Java programs into a clipping web service using Axis. . We also deployed this clipping algorithm into 52North Web processing Service.
Test page URL : http://geobrain.laits.gmu.edu:8099/wps/testgrassclipper.html.

Use case #5 - Stream Extraction from DEM

Import DEM Fill DEM Calculate tangential curvatures Calculate flow accumulation Threshold to extract a stream Thin the result grid to get network segments Export as an GeoTIFF format Export as an tiff image Export as an vector

r.in.gdal r.fill.dir r.slope.aspect r.watershed r.mapcalc r.thin r.out.gdal r.out.tiff r.to.vect

Use case #6 - GRASS Web Application Software System (GWASS)

1. User Data Management: upload new data, download data, delete data and show image
2. Maps Calculator: e.g. calculate a NDVI(Normalized Difference Vegetation Index)
   
3. FFT: Fast Fourier Transform
   
4. IFFT: Inverse Fast Fourier Transform
   
5. Image Mosaic
   
6. Zero-crossing (edge detection)
   
7. Unsupervised Classification
   
8. RGB2HIS: Transform from RGB to HIS
   
9. HIS2RGB: Transform from HIS to RGB
   
10. RGB composite
    
11. Tasseled Cap
    
12. Optimum Index Factor
    
13. Principal Components Analysis
    

See also

• GRASS WEBSERVICES (Date of last revision- 3rd Mar, 2005)
• Constructing BPEL processes using GRASS webservices