Exercise 7: Troubleshooting

How to find out what broke when you get the dreaded pink map or even worse, the GeoMOOSE doesn’t load.

Preparation

We need a tool that lets us see behind the scenes of what is going on in the web browser. The development team uses the Firebug add-on to the Firefox browser for troubleshooting GeoMOOSE. While most browsers now have similar tools built in, this exercise will focus on using Firebug.

  1. Open the Firefox Add-ons page:
../../_images/ex7-install-1.png
  1. Search for the Firebug Add-on:
../../_images/ex7-install-2.png
  1. Install the Firebug Add-on:
../../_images/ex7-install-3.png

Troubleshooting the Pink Map

A pink map is a common error in GeoMOOSE and means that GeoMOOSE was unable to get an image from a WMS server to draw a layer. To see this, we are going to intentionally break a layer.

  1. Go to /srv/geomoose/maps/demo/parcels and edit parcels.map.
  2. Add an extra M to the word MAP on line 21 and save.
  3. Reload GeoMOOSE and you should see the pink screen.
../../_images/ex7-pink-1.png
  1. To see what went wrong, activate Firebug by clicking on the “bug” tool in the browser toolbar and reload the page.
../../_images/ex7-pink-2.png
  1. Click on the “Net” tab and then click “Enable”.
../../_images/ex7-pink-3.png
  1. Reload GeoMOOSE and you should see the list of resources GeoMOOSE requests from the web server.
../../_images/ex7-pink-4.png
  1. Scroll and hover over the mapserv? until you find the one that doesn’t show an image. Then right click and “Open Response in New Tab.
../../_images/ex7-pink-5.png
  1. Read the error message from MapServer.
../../_images/ex7-pink-6.png
  1. Fix the Mapfile (by deleting the extra M added in the beginning)

Troubleshooting failure to load

If GeoMOOSE fails to load completely, it is usually because of an error in the mapbook.

  1. Introduce a structrual error into the mapbook. Change <mapbook version="2.8.0"> into <mmapbook version="2.8.0">. Then reload the interface and see what it does.
../../_images/ex7-mapbook-1.png
  1. Look at the errors in Firebug.
../../_images/ex7-mapbook-2.png

  1. Restore the mapbook and reload the interface to make sure it works again.

  2. Introduce a different error the mapbook. Change the name for the natural_earth map-source so it doesn’t match the path for that layer in the catalog. I.E. change:

    <map-source name="natural_earth" type="mapserver" queryable="true">

to:

<map-source name="natural_earth_" type="mapserver" queryable="true">
  1. Reload the interface and see what it does.
../../_images/ex7-mapbook-3.png ../../_images/ex7-mapbook-4.png