Retrieve part of the dataset, not the entire set

Question

Hi all.
Am currently conducting a research project regarding location based services using Oracle and Java. I have got some datasets for the map of adams county in the US. Currently working with Mapviewer and JDeveloper. I have created a datasource in mapviewer to retrieve the data from the database. but now when i get the image of the map it displays the entire map of the county. i also have a user location function where the user types in their lat/long location and it centers the map to that location.
But what if at every user request instead of loading the entire data i only want to retrieve a small amount of data around the user's location? is that possible in mapviewer? Any help would be greatly appreciated.
Avinash

Answer 1

Hi Avinash,
You can define a MapViewer request with a query window and then just the data inside this query window will be selected. For example, the following map request has the <center> tag, that defines the center and the map size (height).
<?xml version="1.0" standalone="yes"?>
<map_request
  <center size="5">
    <geoFeature>
      <geometricProperty typeName="center">
        <Point>
          <coordinates>-90.0,32.0</coordinates>
        </Point>
      </geometricProperty>
    </geoFeature>
  </center>
</map_request>On MapViewer's Users Guide you will find some other examples. You can also develop programs using the java API which has methods to set your request window (such as setCenterAndSize and others).
Joao