Enabling CORS

Owned by Matt Walker
Last updated: 19 Nov, 2024
2 min read

To allow iShare content to be loaded into a page hosted on a different domain, e.g. to load it into a Spotlight map, you’ll need to allow for CORS. See What is CORS? for more information.

Firstly, on the iShare Maps server install the IIS CORS module from here: https://www.iis.net/downloads/microsoft/iis-cors-module.

The IIS CORS module is configured via the <cors> element as part of the <system.webServer> section. The section can be configured at the server, site, or application level for instance by updating the D:\Astun\iShare\LIVE\WebApps\Web\web.config file. Notes on how to configure the module here: https://blogs.iis.net/iisteam/getting-started-with-the-iis-cors-module.

Configuration

Allow specific sites

This is the most likely scenario, and will allow you to add ol-ishare.services.astuntechnology.com and the domain(s) used by the customer site(s) like so.

<system.webServer> ..... <cors enabled="true"> <add origin="https://ol-ishare.services.astuntechnology.com"> <allowMethods> <add method="GET" /> <add method="HEAD" /> </allowMethods> </add> <add origin="https://*.example.gov.uk"> <allowMethods> <add method="GET" /> <add method="HEAD" /> </allowMethods> </add> </cors> ..... </system.webServer>

Allow all sites

In this simplest example, the CORS module module will allow requests from all origins. Note that this will probably be flagged as a vulnerability by security audits.

<system.webServer> ..... <cors enabled="true"> <add origin="*" /> </cors> ..... </system.webServer>

Testing

To test whether CORS has been enabled :

  • Visit https://ol-ishare.services.astuntechnology.com/v1/apps/spotlight/

  • Open Developer Tools in your browser, then select the Network panel

  • Enter the iShare Maps URL for the site in question into the iShare URL field in Spotlight.

    • For example: https://maps.example.gov.uk

  • If the map doesn't load, then CORS probably isn't enabled. If that is the case you will see a failed/ blocked request in the Network panel for getdata.aspx

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