WHO DARES SUMMON ME!

Oh, hi Evgeny!  Great to see you, hope you're well!

For everyone else, Evgeny is right, of course (because he's quoting me ) but note that in newer versions (IRIS, for instance), you can make use of the %JSON.Adaptor to do something like:

Class Test.DoesItJSON Extends (%RegisteredObject, %JSON.Adaptor)
{
Property aString As %String;
Property anInteger As %Integer;
}

The do something like:

s obj=##class(Test.DoesItJSON).%New()
s obj.aString="Hello"
s obj.anInteger=123
d obj.%JSONExportToString(.jsonstring)
zw jsonstring
    jsonstring="{""aString"":""Hello"",""anInteger"":123}"

This is better for creating new classes (again in later versions than you're on, you need to use the jsonProvider or the altJsonProvider) that you think you're going to want to serialize into JSON.

Hey, I don't work in InterSystems anymore - NOT MY PROBLEM 

In case you missed it below - @Vic Sun pointed out that the IRIS For Health docs should include all IRIS not-for-Health docs as well.