Update WMS exercise

Author: geographika

workshop/content/docs/outputs/wms.md

@@ -2,27 +2,67 @@
 
 ## Overview
 
-We've been using WMS for the example so far. In this exercise we'll look in more detail at how to configure WMS services in MapServer.
+We've been using WMS for interacting with MapServer for Mapfile examples. In this exercise we'll look in more detail at how to configure WMS services in MapServer.
 
+Full MapServer WMS documentation is available [here](https://www.mapserver.org/ogc/wms_server.html). 
 
 ## METADATA Blocks
 
 Web services are configured using `METADATA` blocks. These are key-value pairs, for example:
 
-
 !!! tip
 
     It is good practice to put the key names in quotes. This is not required, but it makes the Mapfile
     clearer that they are strings and not keywords. Keys can also contain strings such as field names, which
     could contain spaces. Without quotes these will cause syntax errors in the Mapfile.
 
+Prefixes are used to configure different types of web service. For example:
+
+- `wms_` is used for WMS services, for example `"wms_title"` can be set in the `WEB` `METADATA` block to set the title of the WMS service. This will be seen when read with client applications such as QGIS. 
+- `wfs_` is used for Web Feature Services.
+- `oga_` is used for the new [OGC Features API](ogcfeatures.md). 
+
+!!! tip
+
+    If settings are to be used for multiple services, then rather than duplicating values for `wms_`, `wfs_` etc. you can use the `ows_` prefix and these settings will apply to all open web services. You can still override this top-level setting for individual service types if needed.
+
+    ```scala
+    METADATA
+        "ows_title" "My Services" # this will apply to WFS GetCapabilities requests
+        "wms_title" "My WMS Services" # this will apply to WMS GetCapabilities requests
+    END
+    ```
+
+## WMS Request Types
+
+There are several different types of WMS request. 
+
+- `GetMap` - for returning map images
+- `GetLegendGraphic` for returning legend images
+- `GetCapabilities` for returning XML metadata of the WMS
+- `GetFeatureInfo` - for returning feature attributes at a query location
+- `DescribeLayer` - returns an XML description of the WMS layer(s)
+
+More details are in [the documentation](https://www.mapserver.org/ogc/wms_server.html#how-does-a-wms-work). 
+
+## GetLegendGraphic
+
+A sample request for the legend for the `polygons.map` is as follows:
+
+- <http://localhost:5000/?map=/etc/mapserver/polygons.map&service=wms&version=1.3.0&request=GetLegendGraphic&layer=buildings&format=image/png&SLD_VERSION=1.1.0>
+
+!!! tip
+
+    The names applied to the legends are based on the `CLASS` `NAME` in the Mapfile. If this is not set then no legend image is created for that layer.
+
+<!--
 ## Output Image Formats
 
 + webp
-
+-->
 
 ## Exercises
 
-1. If you've read this far you deserve to discover one of MapServer's Easter eggs. Try changing the output format to `&format=image`
-
-<https://demo.mapserver.org/cgi-bin/wms?version=1.3.0&request=GetMap&service=WMS&layers=cities&format=image/txt&crs=EPSG%3A4326&exceptions=XML&bbox=-90%2C-180%2C90%2C180&styles=&width=500&height=500&transparent=true>
+1. If you've read this far you deserve to discover one of MapServer's Easter eggs. Try changing the output format to `&format=image/txt`. We'll use the `polygons.map` for the request: <http://localhost:5000/?map=/etc/mapserver/polygons.map&service=wms&version=1.3.0&request=GetMap&layers=buildings&format=image/txt>
+2. Change the legend title for the `polygon map`.
+3. Run a [GetCapabilities](http://localhost:5000/?map=/etc/mapserver/polygons.map&service=wms&version=1.3.0&request=GetCapabilities) request for the `polygon.map`. Add various `METADATA` pairs to get rid of the warnings in the `GetCapabilities` response.

workshop/exercises/app/js/stars.js

@@ -26,6 +26,6 @@ const map = new Map({
     view: new View({
         projection: 'EPSG:4326',
         center: [0, 0],
-        zoom: 4,
+        zoom: 4
     }),
 });

workshop/exercises/mapfiles/polygons.map

@@ -23,6 +23,7 @@ MAP
         CONNECTION "data/osm/buildings_a.fgb"
         CLASSGROUP "offices" # we can switch the default set of CLASSes here
         CLASS
+            NAME "Offices" # this value is used for Legend titles for the CLASS
             GROUP "offices"
             EXPRESSION ( "[type]" = "office" )
             STYLE
@@ -31,6 +32,7 @@ MAP
             END
         END
         CLASS
+            NAME "Other"
             GROUP "other"
             STYLE
                 COLOR 246 241 223