What Is a Polling Trigger

You can use polling triggers if an external application doesn't have an eventing system. In such cases, the external application provides an API call that allows you to retrieve data.

With polling triggers, Oracle Integration periodically queries an external application for new data using an API call. If there is new data, it is retrieved and processed by the integration flow.

You can employ different schemes to poll for new data. Some examples are listed here:

Creation date: Query for records created on a certain date.
Creation time: Query for records created within a certain time interval.
Sequence number: Query for records using their unique ID in the system.

Note:

In this trigger type, Oracle Integration actively queries for data, compares the new data to avoid duplication, and then processes it. For the purpose of comparison, Oracle Integration stores data of the previous query. The stored data is typically known as bag of properties. For details on how to use these properties, see the functions connectivity::getPersistentState and connectivity::setPersistentState in Supported Custom CNCF Serverless Workflow.

What's Supported

Oracle Integration supports the following polling features in a polling trigger:

Singleton polling on cloud (single poller thread per activation)
Acknowledgment or success polling handling
Agent polling
State persistence across polling events
Non-high-availability state persistence across polling events on agent

Definition for Polling Triggers

The following properties are available in the triggers section of an adapter definition document for a polling trigger:

The type property: Specify the trigger type. Set it to polling.
The execute property: Specify the polling method and target. It is executed on each poll.
The polling object with the following properties; this is specific to polling triggers:
- onInit: Specify the initialization flow. It's executed once on activation.
- onSuccess: Specify the flow to be executed on successful publish of polling data on mcube. It's executed once per poll.
- pollFrequencyInSeconds: Specify the frequency of polling. The default value is ten seconds.

Note:

No changes are required in the connection section. The details you specify to connect to the target application are used for the polling trigger as well.
For security configuration, polices that you define in the trigger role are applied to polling calls. The non-http protocol calls use the non-manged policy schema. You must implement a non-managed policy in the protocol handler.

Sample Code

 "pollingTypeTrigger": {
     "displayName": "Polling Type Trigger",
     "description": "This trigger Polls.",
     "type": "polling",
     "execute":"flow:execute",
     "request": {
       "schemaType": "application/schema+json",
       "schema": {
         "$ref": "#/schemas/staticInput"
       }
     },
     "polling": {
       "onInit":"flow:init",
       "onSuccess":"flow:ack",
       "pollFrequencyInSeconds": 3
     }
   },
   "pollingTypeTriggerParallel": {
     "displayName": "Polling Type Trigger parallel",
     "description": "This trigger Polls.",
     "type": "polling",
     "execute":"flow:execute",
     "request": {
       "schemaType": "application/schema+json",
       "schema": {
         "$ref": "#/schemas/staticInput"
       }
     },
     "polling": {
       "onInit":"flow:init",
       "onSuccess":"flow:ack",
       "pollFrequencyInSeconds": 3
     }
   },
   "pollingTypeTriggerCloudParallel": {
     "displayName": "Polling Type Trigger parallel",
     "description": "This trigger Polls.",
     "type": "polling",
     "execute":"flow:execute",
     "request": {
       "schemaType": "application/schema+json",
       "schema": {
         "$ref": "#/schemas/staticInput"
       }
     },
     "polling": {
       "onInit":"flow:init",
       "onSuccess":"flow:ack",
       "pollFrequencyInSeconds": 3
     }
   }