Adding a WFS layer style
How to add WFS layer styles to layers
Alloy allows you to create styles that connect to a WFS (Web Feature Service) server, which allows you to overlay external objects onto your map to provide additional context to your data. A WFS style provides access to feature like point-based measurements, polygon information or Legacy Text product information. The WFS style also handles numeric properties in labels and the ability to get WFS descriptions for style id.
The Web Feature Service (WFS) Interface Standard provides an interface allowing requests for geographical features across the web using platform-independent calls.
WFS styles support the following output formats, JSON, KML, EsriJSON, GML2 and GML3.
Adding a WFS style to a layer
To add a WFS style to a newly created layer use the following procedure:
- When you create a new layer the Styles page is displayed on completion.
- Select the more actions button from the action bar.
- Select Add style. The Create style page appears on the left hand side.
- Select step to define the data source.
You can base a style on one of two data sources:
Design - this allows you to associate the style with a design or design interface, see Adding Layer styles.
WFS - this allows you to associate the style with a Web Feature Service to import and display external information on the map.
When you add a WFS style to a layer it becomes a custom WFS layer, any additional styles that you add to the layer can only be WFS styles.
- Select the WFS option and the Create style is displayed with step one completed.
- Select step to configure the layer settings, the Set WFS parameters form is displayed.
There are two fields to complete:
URL - this allows you to enter the URL for a WFS server that hosts the data that you want to display on the map. The URL is validated and must begin with
https://. If the validation is successful then the connection to the WFS server is established.
WFS version - this allows you to enter the WFS version of the service. This is optional and not required for the link to function, however, some sites require you to specify the WFS version.
- When you have completed the fields, select Next. The second part of the Set WFS parameters form is displayed.
Complete the following fields:
EPSG code - EPSG stands for European Petroleum Survey Group and is an organization that maintains a geodetic parameter database with standard codes, the EPSG codes, for coordinate systems, datums, spheroids, units and similar parameters. You should be able to get the required code from the server you connect to, however, you should check with the service provider to ensure you have the right code.
WFS feature type - this field allows you to define which feature, within the service, that you are connected to. When you select this field a dialog is displayed of the available features within this service. You can select one of the features listed.
- Output format - this field allows you to select the output format of the WFS service, a list of formats is displayed in a dialog. This field is optional, if you do not make a selection the default format, JSON, is used.
- Load all items strategy - by default the feature objects are loaded in tiles within the area that you are viewing. If you select this option then all the objects are loaded on to the map.
A display faded polygon appears when a label title is not present, but the subtitle is present.
Alongside the Next button there is a preview button . This allows you to display the features that you have selected in the WFS feature type field.
When you select the preview button the selected feature details are displayed in the map display, centred on the details within the feature.
- When you have completed the fields select Next. The Create style page is displayed with all the steps shown as completed. Step allows you to configure the basic details of the style. The default settings are applied automatically to these settings.
You can change the default settings when you select step and the Style details page is displayed.
You change the following form fields (all the fields are mandatory):
Name - A name is taken from service, however, you can give the style a meaningful and unique name that can be easily identified.
Colour - This allows you to choose the colour applied to the style icon within Alloy, see Selecting Colours.
Icon - This allows you to choose an icon from the built in library within Alloy to identify the style, see Selecting Icons.
When you have completed all the required fields select Next.
To complete the style select Create. The new style details are displayed in the right panel.