Service Composition for GIS Sai Ma, Minruo Li, Weichang Du Faculty of Computer Science, University of New Brunswick, Canada 2008 IEEE Congress on Services Part I 郭建國

Outline 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? 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 “ ” in front of “wms1Result” and a closing tag “ ” at the end of it, do the same change to “wms2Result”. “ ” and “ ” are added to group all “ ” element toghther.

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

Publish WMC

Export the.bpel file

WMS Map Protal ID:SOC2008 PASSWORD:SOC-2008