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CAP datasource

Please note

Using this datasource requires advanced knowledge.

CAP feeds lack a universally agreed-upon format, resulting in differently formatted XML feeds. While RSS and ATOM formats are common, entirely unique XML formats are also used. Understanding your feed format is essential for proper setup.

Learn more about CAP protocol: official documentation

Create datasource​

Go to Datasources > Click Add new in the External datasource tab > Choose the CAP type.

Operation Mode​

Choose how your CAP datasource receives alerts:

  • Poll Mode: System periodically checks the feed URL for updates
  • Callback Mode: External system pushes alerts directly via webhook (requires webhook integration)

Poll Mode Configuration​

  • For poll mode, decide how your datasource updates: select a Refresh Frequency or specify a Cron Expression

  • Feed URL is mandatory and tells the server where to fetch XML data.

Example: http://alert-feed.worldweather.org/af-andma-en/rss.xml (RSS format feed)
  • Alert URL Selector is optional and required only for unique XML structures. This selector identifies where alerts are located in the feed.
RSS format feeds are parsed automatically, so this field isn't needed for our example.

Here is a snippet from the feed's xml file

<?xml version="1.0" encoding="UTF-8" ?>
<rss xmlns:dc="http://purl.org/dc/elements/1.1/" version="2.0">
  <channel>
    <link rel="alternate" title="RSS" href="http://alert-feed.worldweather.org/af-andma-en/rss.xml"
          type="application/rss+xml"/>
    <title>Latest Official Public alerts for Afghanistan: National Disaster Management Authority</title>
    <link>http://alert-feed.worldweather.org/af-andma-en/rss.xml</link>
    <description>This feed lists the most recent Official Public alerts for Afghanistan:   
      National Disaster Management Authority uploaded to the Filtered Alert Hub.
    </description>
    <language>en</language>
    <copyright>public domain</copyright>
    <pubDate>Tue, 12 Jul 2022 14:48:10 GMT</pubDate>
    <lastBuildDate>Mon, 11 Jan 2021 09:13:00 GMT</lastBuildDate>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <image>
      <title>Latest Official Public alerts for Afghanistan: National DM Authority</title>
      <url>http://alert-feed.worldweather.org/af-andma-en/capLogo.jpg</url>
      <link>http://alert-feed.worldweather.org/af-andma-en/rss.xml</link>
    </image>
    <item>
      <title>Flood warning for Badghis, faryab, Herat, Farah, Ghor, Dykundi provincess of Afghanistan</title>
      <link>https://alert-hub-hko.s3.amazonaws.com/af-andma-en/2022/07/12/14/42/2022.xml</link>
      <description>According to NOAA rainfall prediction for Afghanstan, satellite imagery, GLOFAS,  
        GFMS and iMMAP Heavy rainf in Badghis, Faryab, Herat, Farah, Ghor, Dykundi,   
        Urizgan provincess Province of Afghanistan will lead to flooding, with likely extensive   
        damage to houses and property.
      </description>
      <category>Met</category>
      <pubDate>Tue, 26 Mar 2019 08:24:39 +0000</pubDate>
      <guid isPermaLink="false">urn:oid:2.49.0.1.4.1.2019.3.26.8.24.39</guid>
      <dc:creator>noorimet@gmail.com (Andma)</dc:creator>
      <dc:date>2019-03-26T08:24:39+00:00</dc:date>
    </item>
  </channel>
</rss>

<rss> is the base feed containing <channel> information (title, description) and <item> elements for individual alerts.

The parser automatically sets Alert URL Selector to rss.channel.item.link for this RSS feed.

Advanced caching​

Advanced caching minimizes network traffic by avoiding unnecessary requests.

These settings are optional. Leave empty if unsure about your feed format.
  • Feed last updated selector prevents unnecessary requests when the feed's updated field changes with individual items.
Example: rss.channel.pubDate might indicate feed updates. Setting this selector polls items only when this field changes.
  • Feed item last updated selector avoids requests for unchanged alerts by checking item freshness fields.
Example: rss.channel.item.pubDate might indicate individual item updates. This polls only changed items.

Callback Mode Configuration​

For push-based alert delivery, configure callback mode to receive alerts via webhook.

info

Callback mode requires webhook integration setup in Settings >> Integrations >> Datasource Actions.

When to use callback mode:

  • Real-time alert delivery is critical
  • External system can push alerts to Wallboard
  • Immediate response to emergency alerts is required

When to use poll mode:

  • Standard RSS/ATOM feeds without push capability
  • Less time-sensitive alert scenarios
  • Simple implementation preferred

Webhook Integration​

To enable callback mode:

1. Configure webhook integration:

  • Go to Settings >> Integrations >> Datasource Actions
  • Create a new datasource action with appropriate Event ID
  • Select "Refresh datasource" as the Action Type
  • Note the generated webhook URL

2. Provide webhook URL to external alert system:

  • External systems push CAP alerts to this URL
  • Wallboard processes incoming alerts immediately
  • Authentication must be handled at network/infrastructure level

Screen identification​

Screen identification connects external feed alerts with specific screens in your system.

Only applicable to feeds custom-developed for Wallboard. Standard feeds like our RSS example won't contain this information.

6. Tag based matching identifies which alerts play on which devices:

  • Tag attribute: Choose where screen identifiers are placed in alerts: AUDIENCE, NOTE, ADDRESSES, or AREA_DESC
  • Tag separator: Character separating multiple tags
  • Tag filter type: Tag relationship logic:
    • Any match: Alert plays if any tag matches screen tags
    • All match: Alert plays only if all alert tags match screen tags

Emergency state management​

Requires screen identification configuration. Only works with custom feeds designed for Wallboard.

7. Set screen emergency state automatically enables automatic device emergency state management.

  • Include screens with tag setting: Specifies which devices the server can control. Leave empty for all devices, or specify unique identifiers for specific screens.

Additional settings​

8. Configure additional datasource behavior:

  • Cache external resources: Store external content locally
  • Remove broken external resource references: Clean up invalid links
  • Rotate cache on every update: Clear cache with each refresh
  • Exchange internal resource references: Update internal links
  • Request settings: Configure HTTP request parameters

9. Click Save to create your CAP datasource.