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Scheduler

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Introduction

The support scheduler microservice provide an internal EdgeX “clock” that can kick off operations in any EdgeX service. At a configuration specified time (called an interval), the service calls on any EdgeX service API URL via REST to trigger an operation (called an interval action). For example, the scheduler service periodically calls on core data APIs to clean up old sensed events that have been successfully exported out of EdgeX.

Edgex 2.0

For EdgeX 2.0 the REST API provided by the Support Scheduler has changed to use DTOs (Data Transfer Objects) for all responses and for all POST/PUT/PATCH requests. All query APIs (GET) which return multiple objects, such as /all, provide offset and limit query parameters.

Default Interval Actions

Scheduled interval actions configured by default with the reference implementation of the service include:

  • Clean up of Core-data events/readings that have been persisted for an extended period. In order to prevent the edge node from running out of space, these old events/readings are removed. This is the "ScrubAged" operation. Scheduler parameters around this operation determine how often and where to call into Core-data to invoke this operation to expunge of old data.

NOTE The removal of stale records occurs on a configurable schedule. By default, the default action above is invoked once a day at midnight.


Scheduler Persistence

Support scheduler uses a data store to persist the Interval(s) and IntervalAction(s). Persistence is accomplished by the Scheduler DB located in your current configured database for EdgeX.


Info Redis DB is used by default to persist all scheduler service information to include intervals and interval actions.


ISO 8601 Standard

The times and frequencies defined in the scheduler service's intervals are specified using the international date/time standard - ISO 8601. So, for example, the start of an interval would be represented in YYYYMMDD'T'HHmmss format. 20180101T000000 represents January 1, 2018 at midnight. Frequencies are represented with ISO 8601 durations.

Data Model

The latest developed data model will be updated in the Swagger API document.

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This diagram is drawn by diagram.net, and the source file is here.

Data Dictionary

Property Description
An object defining a specific "period" in time
Id Uniquely identifies an interval, for example a UUID
Created A timestamp indicating when the interval was created in the database
Modified A timestamp indicating when the interval was last modified
Name the name of the given interval - unique for the EdgeX instance
Start The start time of the given interval in ISO 8601 format
End The end time of the given interval in ISO 8601 format
Interval How often the specific resource needs to be polled. It represents as a duration string. The format of this field is to be an unsigned integer followed by a unit which may be "ns", "us" (or "µs"), "ms", "s", "m", "h" representing nanoseconds, microseconds, milliseconds, seconds, minutes or hours. Eg, "100ms", "24h"
Property Description
The action triggered by the service when the associated interval occurs
Id Uniquely identifies an interval action, for example a UUID
Created A timestamp indicating when the interval action was created in the database
Modified A timestamp indicating when the interval action was last modified
Name the name of the interval action
Interval associated interval that defines when the action occurs
AdminState interval action state - either LOCKED or UNLOCKED
Protocol Indicates which protocol should be used. Only http is used today
Host The host targeted by the action when it activates
Port The port on the targeted host
Method Indicates which Http verb should be used for the REST endpoint.(Only using when type is REST
Path The HTTP path at the targeted host for fulfillment of the action.(Only using when type is REST)
Target The service target which is to receive the REST call - example core-data

See Interval and IntervalAction for more information.

High Level Interaction Diagrams

Scheduler interval actions to expunge old and exported (pushed) records from Core Data

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Configuration Properties

Please refer to the general Configuration documentation for configuration properties common to all services. Below are only the additional settings and sections that are not common to all EdgeX Services.

Property Default Value Description
ScheduleIntervalTime 500 the time, in milliseconds, to trigger any applicable interval actions
Property Default Value Description
Default intervals for use with default interval actions
Name midnight Name of the every day at midnight interval
Start 20180101T000000 Indicates the start time for the midnight interval which is a midnight, Jan 1, 2018 which effectively sets the start time as of right now since this is in the past
Interval 24h defines a frequency of every 24 hours
Property Default Value Description
Configuration of the core data clean old events operation which is to kick off every midnight
Name scrub-aged-events name of the interval action
Host localhost run the request on core data assumed to be on the localhost
Port 59880 run the request against the default core data port
Protocol http Make a RESTful request to core data
Method DELETE Make a RESTful delete operation request to core data
Target core-data target core data
Path /api/v2/event/age/604800000000000 request core data's remove old events API with parameter of 7 days
Interval midnight run the operation every midnight as specified by the configuration defined interval

V2 Configuration Migration Guide

Refer to the Common Configuration Migration Guide for details on migrating the common configuration sections such as Service.

API Reference

Support Scheduler API Reference