How to Set Up REST API Scheduled Polling

This guide walks you through configuring scheduled automatic polling for REST API endpoints so that data is imported into Business Central on a recurring basis without manual intervention.

Prerequisites

Permission - You have NAVX IF STANDARD or NAVX IF ALL permission set
REST API Integration - You have a working REST API integration that imports data successfully when run manually (see How to Create a REST API Import Integration)
Job Queue Access - You have permission to create and manage Job Queue Entries in Business Central

What is Scheduled Polling

Scheduled polling automates the REST API import process by creating a recurring Job Queue Entry that runs at a configured interval. Each time the job runs, Business Central calls the REST API, retrieves the latest data, and processes the import, keeping your data synchronized without manual action.

When to Use Scheduled Polling

Scheduled polling is the right choice when:

Regular Sync - You need to keep Business Central data in sync with an external system on a fixed schedule
Unattended Operation - Imports should run automatically in the background
Near Real-Time Updates - You need frequent data updates (as often as every minute)
Batch Processing - You prefer to pull data at scheduled intervals rather than receiving push notifications

Step-by-Step Process

Step 1: Verify Manual Import Works

Before enabling scheduled polling, confirm the integration works correctly by running it manually:

Navigate to Integration Framework > Integrations
Select the REST API integration
Click Import
Verify records are imported and processed without errors

Step 2: Configure Schedule Settings

Open the Integration and navigate to the REST API Endpoint page
In the Scheduled Import section, configure the following fields:

Field	Description	Default
Recurrence (Minutes)	The interval between scheduled runs, in minutes. Range: 1-1440 (1 minute to 24 hours)	60
Earliest Start Date/Time	The date and time for the first scheduled run. If blank, the schedule starts immediately when enabled	(blank)

Step 3: Enable the Schedule

On the REST API Endpoint page, click Enable Schedule
The system creates a recurring Job Queue Entry with the configured settings
The Enable Scheduled Import field changes to Yes
The Last Scheduled Run field will be populated after the first run completes

Step 4: Verify the Job Queue Entry

Navigate to Job Queue Entries in Business Central
Locate the entry with description "REST API Import: [Integration Name]"
Verify the entry is in Ready status
Confirm the recurrence interval and earliest start date/time match your configuration

Disabling the Schedule

To stop scheduled polling:

Open the Integration and navigate to the REST API Endpoint page
Click Disable Schedule
The system deletes the Job Queue Entry and sets Enable Scheduled Import to No

How Scheduled Polling Works

When a scheduled polling job runs, the following sequence occurs:

The Job Queue triggers the REST API Poll Task codeunit
The system verifies the endpoint still has scheduling enabled
The system checks for an active (in-progress) import for the same integration
If no active import exists, the system runs the import
After the import completes, the Last Scheduled Run field is updated with the current date/time
The Job Queue reschedules the next run based on the configured recurrence interval

Overlap Prevention

The system prevents overlapping imports. If a previous scheduled import is still running when the next scheduled run triggers, the new run is skipped. This ensures data integrity and prevents duplicate processing. The system raises an integration event OnScheduledImportSkipped when a run is skipped, which can be used for monitoring through custom AL code.

Retry Logic and Error Handling

Scheduled polling benefits from two levels of error handling:

HTTP-Level Retries

When the REST API returns a transient error, the REST client automatically retries the request (if retry is enabled on the connection). This handles:

HTTP 429 - Rate limited (respects the Retry-After header)
HTTP 500 - Internal server error
HTTP 502 - Bad gateway
HTTP 503 - Service unavailable
HTTP 504 - Gateway timeout
Network errors - Connection failures

Each retry uses exponential backoff, doubling the delay after each attempt. The initial delay and maximum retries are configured on the REST API Connection.

Example retry sequence with default settings (Initial Delay: 1000ms, Max Retries: 3):

Attempt	Delay Before Retry
1st retry	1000 ms (1 second)
2nd retry	2000 ms (2 seconds)
3rd retry	4000 ms (4 seconds)

If the API returns a Retry-After header with a value larger than the calculated delay, the framework uses the Retry-After value instead.

Job Queue-Level Recovery

If the import fails after all HTTP retries are exhausted, the Job Queue Entry handles the error according to Business Central's standard job queue behavior. The Job Queue Entry remains active and will attempt the next scheduled run at the normal interval.

Monitoring Scheduled Imports

Checking Last Run Time

On the REST API Endpoint page, the Last Scheduled Run field shows when the most recent scheduled import completed successfully.

Reviewing Job Queue Status

Navigate to Job Queue Entries
Locate the REST API import entry
Check the Status field:

Status	Meaning
Ready	Waiting for the next scheduled run
In Process	Currently running
Error	The last run failed. Check the Error Message field for details
On Hold	Manually paused. Resume by setting status to Ready

Reviewing Import Logs

After each scheduled run, review the imported data:

Navigate to Integration Framework > Integrations
Open the integration
Review Integration Records for the latest import batch
Check for records in Error status and review error details

Polling Interval Recommendations

Choose the polling interval based on your business requirements and API constraints:

Scenario	Recommended Interval	Notes
Near real-time sync	1-5 minutes	Check API rate limits before using short intervals
Frequent updates	15-30 minutes	Good balance of freshness and API usage
Hourly sync	60 minutes	Suitable for most business data
Daily sync	1440 minutes (24 hours)	Use Earliest Start Date/Time to control the run time
Business hours only	60 minutes	Combine with Earliest Start Date/Time and consider disabling/enabling via a separate job

Best Practices

Test Manually First - Always verify the integration works correctly with a manual import before enabling scheduled polling
Start with Longer Intervals - Begin with a longer interval (e.g., 60 minutes) and reduce it after confirming stable operation
Respect API Rate Limits - Check the API provider's rate limits and set the polling interval accordingly. Frequent polling with short intervals may trigger rate limiting
Enable Retry on the Connection - Keep retry enabled to handle transient API errors gracefully
Set Appropriate Retry Delays - For APIs with known rate limits, set the initial retry delay to accommodate the API's rate limit window
Monitor Regularly - Check the Job Queue Entry status and import logs weekly to catch errors early
Use Earliest Start Date/Time - Set this field to control when the first run occurs, especially for daily imports that should run at a specific time
Review Error Records - After each run, check for records in Error status and address mapping or data issues promptly
One Schedule Per Endpoint - Each endpoint can have only one active schedule. Disable the existing schedule before creating a new one
Plan for Maintenance Windows - When the external API has planned maintenance, consider temporarily disabling the schedule to avoid unnecessary error logs

Troubleshooting

Issue: Schedule is not running

Cause - The Job Queue Entry may be on hold, in error, or deleted
Solution - Navigate to Job Queue Entries and verify the entry exists and is in Ready status
Check - Ensure the Job Queue is running in Business Central (check Job Queue Category setup)

Issue: "A schedule is already active for this endpoint"

Cause - An existing Job Queue Entry is linked to the endpoint
Solution - Click Disable Schedule first, then click Enable Schedule to create a new entry

Issue: Scheduled import skips runs

Cause - The previous import is still running when the next scheduled run triggers
Solution - Increase the polling interval to allow more time for each import to complete, or optimize the integration to process faster
Check - Review the time each import takes and set the interval to at least double that duration

Issue: "Previous import is still in progress" in logs

Cause - The overlap prevention check detected an active import
Solution - This is expected behavior to prevent duplicate imports. If the previous import is stuck, check the import log for errors

Issue: Last Scheduled Run is not updating

Cause - The import is failing before completion
Solution - Run the import manually to see the error, or check the Job Queue Entry error message