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Calem Integration 4: Subscribing to Data Changes via REST API

Data change events and subscription are available in Calem Enterprise R2019b. Administrators can register 3rd-party applications as listeners in Calem. These listeners are notified when records are changed in Calem.

Step 0. What is a Data Change Event

A data change event is a user action to update data including creation, editing, and deletion.

Data change subscription and Calem REST API enable customers to build two-way integration with Calem. This blog discusses the steps to set up event listeners in Calem.

Step 1. Data Change Event Setup

A data change event can be created for Calem to generate data change stream for a table.

  • Menu path: Admin module | Open | Data Change Event
  • Table name defines the table that the data change events should be generated.
  • Track Attributes: use this flag to track changes of category attributes
  • Track Selected: use this flag to track changes of selected base and custom fields defined in the "Field" tab.
  • Optionally track edit, create and delete events.
  • The Sync checkbox will send data change events as part of the data change transaction.
    • This option is useful if you are building a real-time integration and want the user changes to fail if another application reject the changes.
    • Otherwise, the data change events are placed in a queue and will be sent to other applications later as a cron job.

 Step 2. Event Listeners

Event listeners are 3rd-party REST web services.

  • Menu path: Admin module | Open | Data Change Listeners
  • Client Id and Secret are used in the invocation of the REST web service that listens to Calem data change events.
  • Client URL is the web service address.
  • See Calem Enterprise API Guide for more information about authentication and JSON data encoding in building web service listeners.
  • Listeners are then assigned to subscribe to events.

Step 3. Event Queue

Once events and listeners are configured the notification process is executed periodically to send events to listeners.

  • Menu path: Admin module | Open | Event Queue
  • Events are generated and stored in Event Queue.
  • The events will be picked off and queued in Event Notification Queue for notification to listeners.
    • Status "New": events are created.
    • Status "Processed": events are queued in notification queue.
    • Use Event Notification Queue to view the notification status.
  • Event Queue can be browsed and searched by list search row

Step 4. Event Notification Queue

Event Notification Queue shows the status of event notification.

  • Menu path: Admin module | Open | Event Notification
  • Event notification statuses are recorded in this list for one to review what events are notified or there are errors in the notification.
    • Status "New": queued for notification
    • Status "Processed": notification successful
    • Status: "Failed": unable to notify a listener - see "Comment" field for error messages.

 Step 5. Integration Monitors

Integration monitors can be configured to receive email notifications when errors happen in outbound event notification.

  • Menu path: Org module | ACL Profiles | Monitor User
  • "Integration Monitor" role may be defined for users to receive error notifications.
    • "Site" field may be populated to receive notification for a site.
    • Set "Site" field to empty to receive notification from all sites.
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