Simple $system.Event examples

The attached file contains two $system.Event examples that processes work asynchronously using persistent queues:

• Events_Simple.prj.xml
• Events_PubSub.prj.xml - updated this example has been published on https://github.com/intersystems-ib/cache-iat-pubsub

Events_Simple

This is a very basic example that creates some worker processes and then enqueue messages to them using $system.Event.

; create shared resource, create worker jobs.
USER>do ##class(IAT.S04.Event.Test).Setup()
 
; enqueue some messages to workers and see what happens
USER>do ##class(IAT.S04.Event.Test).Run()
Show log? no/[yes]:
^Samples.Log=10
^Samples.Log(1)="[2016-02-19 09:43:14] Enqueuing 1"
^Samples.Log(2)="[2016-02-19 09:43:14] Worker 8168 grabs: 1"
^Samples.Log(3)="[2016-02-19 09:43:14] Enqueuing 2"
^Samples.Log(4)="[2016-02-19 09:43:14] Worker 18184 grabs: 2"
^Samples.Log(5)="[2016-02-19 09:43:14] Enqueuing 3"
^Samples.Log(6)="[2016-02-19 09:43:14] Worker 8168 grabs: 3"
^Samples.Log(7)="[2016-02-19 09:43:14] Enqueuing 4"
^Samples.Log(8)="[2016-02-19 09:43:14] Worker 18184 grabs: 4"
^Samples.Log(9)="[2016-02-19 09:43:14] Enqueuing 5"
^Samples.Log(10)="[2016-02-19 09:43:14] Worker 8168 grabs: 5"
 
; we are done. we could enqueue more messages or just kill worker jobs.
write $system.Process.Terminate(8168)
1
write $system.Process.Terminate(18184)
1

Classes:

• Manager - methods to create shared resources and workers as well as to enqueue messages to workers.
• Queue - simple persistent class used to store messages
• Worker - worker class that waits for an event and processes the received message

Events_PubSub

This example is based on the same foundations as Events_Simple.

The goal here is building a simple Publisher-Subscriber model.  

There are two subscribers:

• SubPatient which handles Patient related messages.
• SubDummy which handles dummy messages.

; create events and subscriber jobs
do ##class(IAT.S05.PubSub.Example.Main).Setup()
; send some messages to channels
do ##class(IAT.S05.PubSub.Example.Main).Run()
; show log
zw ^PubSub.Log

Main classes:

Example classes:

Log: