Scheduling BC
Multiple processes and events in BCs across the Mojaloop Switch platform require functionality to trigger at specific times, or in accordance with a schedule. In order to support this requirement across the Switch, and avoid building scheduling functionality into multiple BCs, a single Scheduling BC will be introduced and implemented for the Switch platform.
In order to schedule a process or event, a Client BC submits a request to the Scheduling BC to create a reminder for a specific time or time schedule. The Scheduling BC maintains a schedule of all of the reminders that it receives, and, as the time for reminders is reached, it sends notification of the reminder to the appropriate Client BC.
In addition, the Scheduling BC will also provide services to the Switch to enable Client BCs and Switch Admins to manage reminders that are set within the Scheduling BC.
Terms
The following common term/s are in use in this BC:
Client BC
Any other BC making use of the Scheduling BC Services
Use Cases
The status of the UCs for the Scheduling BC is as follows:
Use Case
Description
Use Case
Description
Create Reminder
Client BC requests a reminder to be created
Client Reminder Query
Client BC queries its own reminders
Delete Reminder
Client BC requests a reminder to be deleted
Admin Reminder Query
Platform Admin queries all reminders
Reminder Trigger
Scheduling BC executes reminder trigger when the time comes
Update Reminder
Not provided. Recommended solution: delete and create a new Reminder
Create Reminder
Description
The workflow provided by this UC enables the Switch to handle authorised Client BC requests to create Reminders.
Flow Diagram
Reminder Triggered
Description
The workflow provided by this UC enables the Switch to handle reminders messaged from the Scheduling BC to a Client BC to execute a task, or as a reminder only.
Flow Diagram
Delete (Recurring) Reminder
Description
The workflow provided by this UC enables the switch to handle messages from authorised Client BCs to the Scheduling BC to delete a Reminder. In the event that the Scheduling BC is unable to process the instruction, it sends an Alert message to the Notifications BC.
Flow Diagram
Notes
Create Reminder - Required data
The Create Reminder request needs to include the following data:
Identifier
name/id
Cron Definition
recurring?, time interval?
Trigger Transport
HTTP Callback/Event; Callback URL or Event Topic
Special Payload
opaque for the scheduling BC
Recovery Conditions
retry, reschedule, abort, abandon
Alerts
notification, logging on exceptions
Actions
register of automatable/schedulable BC processes
Scheduling BC - Requirements
The Scheduling BC must meet the following requirements:
Reminders must be triggered once only
BC must keep track of triggered Reminders
BC must keep track of Create/Read/Delete actions
Updates will be facilitated through Delete/Create actions as noted in the Use Case Available UCs list
Job batches
Offer multiple interface options (gRPC, REST, HTTP, etc.)
Reminders should be triggered with an HTTP callback, not a gRPC call, or to a specific topic
It should have no ability to process logic external to the Scheduling BC itself
Make use of Linux-based UTC timestamps only in order to avoid synchronization issues
Note: It is assumed that the underlying system will keep perfect time.
Scheduling BC - Outstanding requirements
Access requirements for the Scheduling BC still require definition.
Scheduling BC - Exceptions
Malformed instructions
Invalid date/time, including times in the past
Invalid BC or command
Failed execution (identified through call-back)
Insufficient authority for the Client BC to perform the CRD operation
Failure to process/execute Reminder
Questions
A number of questions came up during the Reference Architecture Work Sessions and, as some were felt to have potential value from which others would benefit, we have included them below:
After the scheduled task has been initiated, does the Scheduling BC remain responsible for tracking its progress?
Answer: No. When the Reminder is due, it is communicated to the Client BC using the precribed method, and thereafter, the Scheduling BC responsibility for the reminder is passed back to the Client BC.
Is the Client BC or the person who scheduled a Reminder noted as the "User" by the Scheduling BC? IOW, whose ID is stamped on the process audit trail?
Answer: This should be determined by the Client BC, based on its action on receipt of the Reminder.
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