Scheduler

The Scheduler is a way of declaring tasks to execute on a given schedule and time zone. It provides an easy to use SDK for scheduling, automatic de-scheduling and re-scheduling for event tasks.

Demo Code

PerigeeApplication.ApplicationNoInit("Demo Scheduler", (c) =>
{
   
    //Declare a new memory source, remember to use a single instance of memory/file based sources or locking can occur
    using var MemSource = new MemoryScheduledSource("memSource.json", c.CTS.Token);

    //Add scheduled items.
    //If this was something like a DatabaseScheduledSource, we obviously would control these records from the database, not here.
    MemSource.AddIfNotExists(GenericScheduledItem<ushort>.MemoryItem(0, "A scheduler, 15sec", "A", "a;b;c", "*/15 * * * * *", TimeZoneInfo.Local));
    MemSource.AddIfNotExists(GenericScheduledItem<ushort>.MemoryItem(1, "B scheduler, 45sec", "B", "b;c;d", "45 * * * * *", TimeZoneInfo.Local));

    //Add a scheduler with the MemorySource, a single callback is given for anything required to run (multi-threaded)
    c.AddScheduler("Main", MemSource, (ct, l, item) => { 
        if (item.GetRunType() == "A")
        {
            l.LogInformation("Running A with {args}", item.GetRunArgs());
        }
        else if (item.GetRunType() == "B")
        {
            l.LogInformation("Running B with {args}", item.GetRunArgs());
        }

    });

});

The demo code uses the Memory Scheduler as it does not require a remote source. Typically speaking you would tie the event task descriptions back to a database record (like the MSSQL Scheduler Source).

• Line 5 - Declare a new event source. This demo uses the memory scheduler.

• Line 9-10 - Add the two scheduled items, A, and B, to schedule and execute

• Line 13 - Add a scheduler using the source we defined, and declare the callback.

  • You're given a CancellationToken for respecting graceful shutdown event.

  • An ILogger for logging to the system and defined sink sources.

  • And the GenericScheduledItem<ushort> Which is the interfaced item that allows you to access it's definition values.

• Line 14 - You can execute or perform any tasks you need. Like generating a report with parameters.

  • You can see the call to GetRunType(). There's also GetRunArgs(), GetLastRunDate(), GetName(), etc.

SDK

Memory Source

The Memory source stores all records, run times, and event descriptions on the path specified. It's a great way to test, debug, or play with the scheduler without having to stand up a database. Typically speaking for production scenarios, you would likely use a remote source, like a database or file to maintain the scheduled items.

//Declare a new memory source, remember to use a single instance of memory/file based sources or locking can occur
using var MemSource = new MemoryScheduledSource("memSource.json", c.CTS.Token);

//Add scheduled items.
//If this was something like a DatabaseScheduledSource, we obviously would control these records from the database, not here.
MemSource.AddIfNotExists(GenericScheduledItem<ushort>.MemoryItem(0, "A scheduler, 15sec", "A", "a;b;c", "*/15 * * * * *", TimeZoneInfo.Local));
MemSource.AddIfNotExists(GenericScheduledItem<ushort>.MemoryItem(1, "B scheduler, 45sec", "B", "b;c;d", "45 * * * * *", TimeZoneInfo.Local));

MSSQL Source

MSSQL Source is the example remote source included with the Scheduler. This source pulls records from a table in MSSQL which allows for 1 database record to create and maintain 1 scheduled task.

Using the MSSQL source is very easy, it only required a registered connection string credential.

//Register the connection string credential
CredentialStore.RegisterRefresh("MSSQL", (o) => new ConnectionStringCredentialStoreItem() { ConnectionString = c.Configuration.GetConnectionString("TestDB") });

//Supply it to the MSSQL Scheduled Source:
// Partition, CredentialName, Schema, TableName
var SQLSource = new MSSQLScheduledSource("Prod", "MSSQL", "dbo", "Scheduler");

The code can actually be found linked below.

Generic Scheduled Item <ushort>

This The included scheduled item interfaced class. It's suitable for most scenarios, but as the whole callback process is interfaced, you're able to implement your own class to use if needed.

Below are the interfaced methods for a scheduled item. These methods provide an easy way to retrieve the relevant properties on a scheduled task regardless of where that event description came from (in a database, a file, remotely, etc).

 public interface IScheduledItem<T>
{
    public string GetName();
    public T GetID();
    public string GetCRON();
    public TimeZoneInfo GetTimeZone();

    public DateTimeOffset? GetLastRunDate();
    public DateTimeOffset? GetCreateDate();

    public string GetRunType();
    public string GetRunArgs();

    public DateTimeOffset? GetNextOccurance();

}

Code for Sources

Memory:

This memory source shows the most simplified way possible of implementing the interface and can be used to learn how it works.

5KB

IScheduledSource_Memory.cs

MSSQL:

If you're writing a custom connector to another database engine, this is a great template and guide to do so:

7KB

IScheduledSourceMSSQL.cs