A RESEARCH PROJECTResearch focus: virtual data integrationExploring feasibility of the approach• Advantages• Limitations• Challenges• Best practices
WHAT WE HAVE DONECombined existing county Web map servicesinto single multi-county online parcel mapCounties supplied REST service endpoints• No physical data exchange• No edgematching or common data model• Web map points to published county dataset (most current data)
WHAT ARE WEB SERVICES?It depends on who you askTechnology perspective• Software and standards supporting computer interaction over the InternetUser perspective• Web apps offering data, product, or service delivered over Web
WHAT ARE WEB MAP SERVICES? Technically • Web Map Service = WMS • OGC standard for online maps display • One of a family of standards Generically • Way to deliver map content over Web • Also, feature and geoprocessing services…
OUR GOALSProject goals broadened over timeInitial goal: create multi-county parcelWeb mapOur focus now is on the research side• Not just parcels, but any theme• Limitations, challenges, best practices• Alignment with other GIS/IT trends
OUTLINE OF PRESENTATIONBackground (Howard)Project status (Brenda)Main challenges (Howard)• Performance• Availability of map services• Resymbolization and map appearance• Distributed analysis and querying• Legal issues
GEOSPATIAL DATA INTEGRATION “Combining data from different sources to provide a unified view of data for users” A mashup combines different geospatial themes over one area. Data integration combines the same theme over different (adjacent) areas.
ADVANTAGE #1“Well-behaved” problemOnce source datasets are delivered, nofurther external inputs are neededRelatively easy to allocate personnel andbudget to the task
ADVANTAGE #2True integration is possible (in theory)Rubber sheeting and edgematchingeliminate spatial “gaffs” (slivers, overlaps)Common data model facilitates analysisand querying
ADVANTAGE #3Republishing is relatively easyIntegrator can make data available in avariety of formats
DISADVANTAGE #1Data producers provide copy of datasetIssues:• Data sharing arrangements• Loss of local control over data• Possible quality decline due to spatial and/or attribute adjustments
DISADVANTAGE #2Integrated data may not be currentDepends on time it takes to performintegration, plus volatility of the layerRe-integrating updated data is frequentlycostly (so often never happens)
DISADVANTAGE #3Curating integrated datasets isincreasingly impracticalLarge data volumes (“big data”)More frequent updates, data collection
Need a solution thatincorporates distributed access, visualization, analysis and querying
PROCESS Dear <<LIO>>, This email is to inform you of a joint research project by the State Cartographers Office (SCO) at UW-Madison and the Department of Geography and Anthropology at UW-Eau Claire. The purpose of our project is to investigate the feasibility of using Web map services to create a statewide view of geospatial data collected and maintained at the county level.Supported and Our initial goal is to incorporate existing map services showing tax parcels into a singlefacilitated by LION online map application. We have chosen parcel data for this initial test because this type of data is of interest to a wide range of users. However, our project has a broader purpose, namely to explore how Web map services can be used to support virtual data integration for simple mapping and display. Specific research questions we will be investigating include: - How much flexibility exists to resymbolize map services from different counties? Can weContacted stakeholders apply a common set of map symbols to different services to make the integrated map look more consistent? - What are the limitations on querying and analysis, given that data models and attributes(county LIOs) via email are not consistent from county to county? What implications does this have for data standards? - How much of an issue is performance? Are there performance improvements that can be implemented? - Can we integrate commercial and open-source services in a single Web application?Gathered REST URL Since our approach makes use of existing Web map services, we do not need to ask for copies of your geospatial datasets. Instead, we will simply be tapping into existing services(or other URL) that are already available on the Web. This also means that any map that includes your countys data will be up-to-date and accurate. We do have one request. We would greatly appreciate your assistance by providing the URL of your parcel data Web service. For most counties, this will be an ArcGIS Server REST endpoint of the form:Followed up in person https://<host>/ArcGIS/rest/servicesor by phone We are also interested in other types of services -- such as ArcIMS, WMS, etc. If you have such a service, we would appreciate your help identifying its URL. To provide us with your URL, simply reply to this email or to one of the email addresses listed below. So that we can keep on schedule for our project, we would greatly appreciate a response by May 1, 2012. Please let us know in your email response if you have any conditions or terms associated
REST ENDPOINTSRepresentational State TransferA communications protocol for the Webhttp://example.wi.us/arcgis/rest/servicesOnce a service is published through ArcMapto ArcGIS Server it is visible at the REST URL
PERFORMANCEMany county REST services designed forinternal access or occasional citizen useImpact on these users if site usageincreased significantly?One of the reasons we are not releasing apublic-access viewer at this time
SERVICE AVAILABILITYServices can be added, removed, ormodifiedAffects where the map viewer points tothe dataServices may also go off-lineVirtually no control over these changes
SERVICE AVAILABILITY Map servicenot responding
RESYMBOLIZATIONNeed to control symbol color and sizeAlso need to control zoom levels wherefeatures appear and disappearRelatively easy todo, but littleconsistency orstandardizationbetween counties
DISTRIBUTED QUERYINGHow to query across multiple datasetswith different schemasA big research issue (“semantic web”)“Distributed query” or “federated search”user query subqueries to participatingdata sources aggregation of query results
LEGAL ISSUESOpens up new legal issuesData readily incorporated into anymashup for any purposeLoss of control over dataHow will local governmentsreact to this new technology?
WHO BENEFITS FROM INTEGRATED DATA?Geospatial professionals• Demonstrate ROI for cost of geospatial services• Model a successful data integration scenarioCounties• Active participants in an effort that will have impacts beyond county boundariesCitizens and taxpayers• Maximizing utilization of taxpayer investments• Obtaining greater benefits• More effective and efficient governance!
BENEFITS OF STUDYEducation about GIS Web servicesForward-looking way of thinking about data integrationChallenges and solutions to this new approachStandards and best practices for Web services