In addition to Ben's answer, 

on Windows: netstat -ano | find "LISTENING"

will in the far right column show the process ID of the listening process

on Linux: sudo netstat -pln | grep tcp

the last column shows the process name which is opened the port

I think, there is a "small problem" at start...

zn "%SYS",n=SL ...

will not work as expected ;-))

but what about this line with 552 chars

zn "%SYS" s n="SL" d ##class(Security.SSLConfigs).Create(n):'##class(Security.SSLConfigs).Exists(n),##class(%Net.URLParser).Parse("https://pm.community.intersystems.com/packages/zpm/latest/installer",.c) s h=##class(%Net.HttpRequest).%New(),h.Server=c("host"),h.Port=443,h.Https=1,h.SSLConfiguration=n,s=h.Get(c("path")) q:'s $System.Status.GetErrorText(s) s x=##class(%File).TempFilename("xml"),f=##class(%Stream.FileBinary).%New(),f.Filename=x d f.CopyFromAndSave(h.HttpResponse.Data) d h.%Close(),$system.OBJ.Load(x,"ck") do ##class(%File).Delete(x)

I only rewrote your line, but haven't tried to execute

I think, your solution is an  "ad hoc" solution for a particular task, anyway, I want to point out two problems.

First, the solution fails, if the size of <source> is less then than the size of <target>:

set source={"Name":"Joe", "Age":50 }
set target={"Name":"Joe", "Age":50, "Phone":"123-456"}

write CompareJSON(source,target) ---> 1
write CompareJSON(target,source) ---> 0

The same goes for data like:

set source={"Name":"Joe", "Age":50, "Data":[10,20] }
set target={"Name":"Joe", "Age":50, "Data":[10,20,30]}

Maybe your data do not have such cases.

A quick check could be:

if source.%Size()-target.%Size() { quit "Size-problem" }

Second, in a more "general" case, comparing lists could sometimes lead to an philosophical question:
are two lists with the same elements but in a different sequence (of those elements) equal or not?

list1: [aaa, bbb]
list2: [bbb, aaa]

The answer MAY depend on the question, what is stored in those lists?

If the lists contains, for example, some kind of instructions, then the sequence of those instructions will mattern, but if those list are just list of, say my hobbies, then the sequence is unimportant (except, if one implies some kind of weighting, like the first entry is my preferred hobby).

This implies to me, to compare two list, you MAY need an extra info, something like:
dependsOnSequence = yes | no

One more hint, in the line

s tSC= ..CompareJSON(value,target.%Get(key),RefNo)  

what happens if target.%Get(key) is empty (or not a corresponding object)?

Just my2cents