Service Composition Service Composition for GISfor GIS

Sai Ma, Minruo Li, Weichang Du

Faculty of Computer Science,

University of New Brunswick, Canada

2008 IEEE Congress on Services 2008 - Part I

69721027 郭建國

OutlineOutline

Introduction Geographical Information System(GIS)

Background OpenGIS WMS & WMC

Solution SOA Framework for GIS Map Services Composition via BPEL

Implementation & Demonstration Perspective & Conclusion

What is GIS?What is GIS?

Geographical Information System Provide a method to visualize , analyze and

manipulate geospatial data. Geographical maps via Services

Consider the process of visualizing , analyzing and manipulating geospatial data as services.

An issue within the GIS community Various geospatial data are stored in different

data formats suitable for different systems.

OpenGIS WMS & WMC

Web Map Service (WMS) Be used to publish a map service Based on XML Schema

Web Map Context (WMC) Describes an instant map view information

Web Map Service

Operations GetCapabilities GetMap GetFeatureInfo

Web Map Service

GetCapabilities request URL

Web Map Service

The parameters of a GetMap request

Web Map Service

The parameters of a GetFeatureInfo request

Web Map Context

In contrast to WMS , WMC describes an instant map view from the perspective of the map creator , which contains the WMS layer components , the bounding box and map title.

Map Services Composition via BPEL We use ActiveBPEL as the tool to handle all

BPEL related work in our application system. Configure Database

Gathers as many existing maps services and parses them into database

Solution with SOA and BPEL

Generate Business Process

Map Services Composition via BPEL Generate Business Process

NewMapViewRequest AssignRequest WMFSFlow InvokeWMS1 & InvokeWMS2 CompeseLayers InvokeMapCreationService AssignResponse NewMapViewResponse

Map Services Composition via BPEL

NewMapViewRequest Get URL, layer name, bounding box, format, height, and

width information from WMS1 and WMS2. AssignRequest

Initializes parameters “wms1Url”, “wms1LayerName”, “bbox”, “format”, “height”, and “width”

Assigns these parameters to each “InvokeWMS” activity in the “WMSFlow”.

In the mean time , create “wms1Result” and “wms2Result” to hold each URLs resulting from previous WMS.

Map Services Composition via BPEL Combine the two map layers, add an opening

tag “<layer>” in front of “wms1Result” and a closing tag “</layer>” at the end of it, do the same change to “wms2Result”.

“<layers>” and “</layers>” are added to group all “<layer>” element toghther.

Map Services Composition via BPEL

Map Services Composition via BPEL

WMFSFlow Get information from AssignRequest Invokes WMS1 and WMS2 in parallel

InvokeWMS1 & InvokeWMS2 CompeseLayers

Concatenate the two URLs into one single string and pass it to “InvokeMapCreationService”

InvokeMapCreationService Create a new image by calling external JAVA libraries to

read each map layer pixel by pixel

Map Services Composition via BPEL

AssignResponse Assigns the resulting URL to “NewMapViewResponse”

NewMapViewResponse Responds to the map creator by delivering this URL to

map creator.

Map Services Composition via BPEL Two additional activities will be added

“ApplyTemplate” and “AssignLayers” To apply some predefined templates to add

site-specific information to the new map during the map creation process Such as company logo or name.

Map Services Composition via BPEL

ApplyTemplate Applies some predesigned map templates before

creating the new map AssignLayers

Adds the “layers” variable to the template response and passes it to the “InvokeMapCreationService”.

Interface

Interface

Publish WMC

Export the .bpel file

WMS Map Protal ID:SOC2008 PASSWORD:SOC-2008