[Geoserver-users] Tracking vehicles

SenTnel2 · June 28, 2006, 7:55pm

Hi!

I'm a new GeoServer user and I was wondering if someone could help me with
the issue of plotting a point knowing the coordinates, this is so I could
use the gps data that is updating constantly at a SQL database (I could use
MySQL if necesary).

Thanks !
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Brent_Owens1 · June 28, 2006, 9:39pm

You can use a WFS insert request with geoserver to save the point to your dataset. Geoserver comes with several demo requests under the 'demo' section of the web-admin gui. In those requests is an example for inserting data (in this case a lineString). Here is the request:

<wfs:Transaction service="WFS" version="1.0.0"
  xmlns:wfs="http://www.opengis.net/wfs"
  xmlns:topp="http://www.openplans.org/topp"
  xmlns:gml="http://www.opengis.net/gml"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://www.opengis.net/wfs http://schemas.opengis.net/wfs/1.0.0/WFS-transaction.xsd http://www.openplans.org/topp http://localhost:8080/geoserver/wfs/DescribeFeatureType?typename=topp:tasmania_roads">
  <wfs:Insert>
    <topp:tasmania_roads>
      <topp:the_geom>
        <gml:MultiLineString srsName="http://www.opengis.net/gml/srs/epsg.xml#27354">
          <gml:lineStringMember>
            <gml:LineString>
              <gml:coordinates decimal="." cs="," ts=" ">
494475.71056415,5433016.8189323 494982.70115662,5435041.95096618
              </gml:coordinates>
            </gml:LineString>
          </gml:lineStringMember>
        </gml:MultiLineString>
      </topp:the_geom>
      <topp:TYPE>alley</topp:TYPE>
    </topp:tasmania_roads>
  </wfs:Insert>
</wfs:Transaction>

Once you have built up the request, just send it to your geoserver instance, like this:
http://localhost:8080/geoserver/wfs

Hope that helps.

Brent Owens
(The Open Planning Project)

SenTnel wrote:

Hi!

I'm a new GeoServer user and I was wondering if someone could help me with
the issue of plotting a point knowing the coordinates, this is so I could
use the gps data that is updating constantly at a SQL database (I could use
MySQL if necesary).

Thanks !

SenTnel2 · July 7, 2006, 3:21pm

Thank you Brent!

We tried to implement this as per your instructions but we see that the
problem here is that we are not very familiar with this terms.

How do we tell geoserver the coordinates of the vehicle? I mean, we are
using MySQL server and we have created (for testing purpose) a table with
just four fields: ID, VehID, Lat and Long

The lat long fields are being updated every minute.

Basically what we dont know is how we tell geoserve to plot a point a these
lat long every minute.

Thanks a lot!

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Gerald_Estadieu1 · July 7, 2006, 5:33pm

If I understand well you have a database that include the long/lat values from GPS receivers and you want to use it through GeoServer to plot on a map.
In that case, you must have a geometry field in your database (for MySQL only after 4.1 version) according to the OGC standards. Your 2 columns long and lat cannot be used directly. Either you write an external program to transform them into a geometry field or you can maybe do it in a MySQL function. Once you have this, you will be able to simply connect to it with Geoserver and show a map.
To recap: you must create a new column in your table let’s call it ‘the_geom’ with a type ‘geometry’. Everytime you update your long/lat you must update your the_geom as a POINT(x,y). Geoserver cannot read directly your long/lat column but it will use the_geom.
I hope it helps you.

Gerald

On 7/7/06, SenTnel <epwise0707@anonymised.com> wrote:

Thank you Brent!

We tried to implement this as per your instructions but we see that the
problem here is that we are not very familiar with this terms.

How do we tell geoserver the coordinates of the vehicle? I mean, we are
using MySQL server and we have created (for testing purpose) a table with
just four fields: ID, VehID, Lat and Long

The lat long fields are being updated every minute.

Basically what we dont know is how we tell geoserve to plot a point a these
lat long every minute.

Thanks a lot!

–
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SenTnel2 · July 7, 2006, 10:16pm

Thanks a lot!

Worked for us! we already have the point plotted on the map. Now we have
two more tricks to learn:

1> how do we select an specific vehicle? in our table we have different
vehicles, when we ran the application it showed all of them at once... we
want to be able to select wich vehicle we want to display.

2> how do i tell geoserver to go and refresh the position periodically

Thanks again
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Chris_Holmes1 · July 7, 2006, 10:27pm

SenTnel wrote:

Thanks a lot!

Worked for us! we already have the point plotted on the map. Now we have
two more tricks to learn:

1> how do we select an specific vehicle? in our table we have different
vehicles, when we ran the application it showed all of them at once... we
want to be able to select wich vehicle we want to display.

You can use a FILTER in your SLD file (SLD is how you specify what the map should look like). You'll have to dig in to the docs a bit, but you can make different filters for your different vehicle names/numbers.

2> how do i tell geoserver to go and refresh the position periodically

Well, if you're database updates, then you just have to make a request to GeoServer again. You'll have to do the calls to refresh on the client side, add some code to whatever client you're using.

Chris

Thanks again

--
Chris Holmes
The Open Planning Project
http://topp.openplans.org

Brent_Owens1 · July 7, 2006, 10:40pm

1) This one is a little tricky but doable. It involves putting a filter into your SLD file that will render only vehicles with the specified ID. Now this isn't hard if you always want to render the same vehicle. But if you want the user to be able to select which vehicle to render, then you will have to do a WMS request with SLD POST (passing a custom SLD along with the WMS request). There are several examples on the geoserver docs page on SLDs and SLD post.

2) This depends on what client you are requesting the map with. If you are using MapBuilder or OpenLayers, you can just just use a javascript setInterval() function to refresh every few seconds. But as long as the data is being updated in geoserver, it will always render everything you ask it to. So just keep making getMap requests.

Brent Owens
(The Open Planning Project)

SenTnel wrote:

Thanks a lot!

Worked for us! we already have the point plotted on the map. Now we have
two more tricks to learn:

1> how do we select an specific vehicle? in our table we have different
vehicles, when we ran the application it showed all of them at once... we
want to be able to select wich vehicle we want to display.

2> how do i tell geoserver to go and refresh the position periodically

Thanks again

SenTnel2 · July 8, 2006, 12:04am

Thanks guys! you are great! I can't believe that you are wiling and able to
help people this way, without knowing the people nor charging for it...

I was going to say "my last question", but rethinking, when you are working
on a project you can never say that...

One more: I would like to apply the styles dinamically, without using the
GUI, can I load the styles externally?

Thanks again
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Brent_Owens1 · July 8, 2006, 12:35am

We are always here to help =)

For applying the style dynamically, yes you can with the recent version of geoserver. It has a pseudo implementation of PutStyles where you can submit an SLD file over WMS using POST. Just send an XML document to http://localhost:8080/geoserver/sld
(of course fill in the proper server URL).
The body of the SLD needs to have a 'named layer' tag (your feature type you are setting the SLD for) and a 'user style' (the SLD).
Here is an example one:

<?xml version="1.0" encoding="UTF-8"?>
<StyledLayerDescriptor version="1.0.0"
  xmlns:gml="http://www.opengis.net/gml"
  xmlns:ogc="http://www.opengis.net/ogc"
  xmlns="http://www.opengis.net/sld">
  <NamedLayer>
    <Name>states</Name>
    <UserStyle>
      <Name>states_style</Name>
      <Title>geoserver style</Title>
      <Abstract>Generated by GeoServer</Abstract>
      <FeatureTypeStyle>
      <Rule>
        <PolygonSymbolizer>
          <Fill>
            <CssParameter name="fill">#EEEE55</CssParameter>
            <CssParameter name="fill-opacity">1</CssParameter>
          </Fill>
          <Stroke>
            <CssParameter name="stroke">#FF0000</CssParameter>
            <CssParameter name="stroke-opacity">1</CssParameter>
          </Stroke>
        </PolygonSymbolizer>
        <TextSymbolizer>
          <Label>
            <ogc:PropertyName>STATE_FIPS</ogc:PropertyName>
          </Label>
            <Font>
              <CssParameter name="font-family">Times New Roman</CssParameter>
              <CssParameter name="font-style">Normal</CssParameter>
              <CssParameter name="font-size">12</CssParameter>
            </Font>
          <Fill>
            <CssParameter name="fill">#775577</CssParameter>
            <CssParameter name="fill-opacity">1</CssParameter>
          </Fill>
        </TextSymbolizer>
      </Rule>
      </FeatureTypeStyle>
    </UserStyle>
  </NamedLayer>
</StyledLayerDescriptor>

Brent Owens
(The Open Planning Project)

SenTnel wrote:

Thanks guys! you are great! I can't believe that you are wiling and able to
help people this way, without knowing the people nor charging for it...

I was going to say "my last question", but rethinking, when you are working
on a project you can never say that...

One more: I would like to apply the styles dinamically, without using the
GUI, can I load the styles externally?

Thanks again

SenTnel2 · July 8, 2006, 12:45am

How do I use the setInterval function? I can't find any reference about the
use of it...

needless to say thanks again? no way... Thanks again!
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