PubSub - Publish Messages

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I have a very simple and from the book PubSub requirement

I get some data. I transform it to a Json text and publish it to a topic.

All the subscribers to that topic should get that json data . All my subscribers request message has one property

Property JSONData As %Text(MAXLEN = 100000)


- I have made the Domain, Subscibers and defined the targets for each subscriber depending on topic

- I have added an out of the box PubSub Operation too

- Where I am right now is that I have the json data and from my bp I call the pubsub op with the domain name, topic name and json.

It gives me back the list of subscribers and thats it. (This is also what documentation says)

But if we stop here than the basics of pubsub is compromised. The pubsub model should send messages to all its subscribers.

Does someone or Intersystems has any example or a BP made where pubsub messages is getting broadcasted to all its subscribers?


Thanx to all and esp to Eduard

I used a mix of Eduard's code, docs, EnsLib.PubSubOperation and some of my code

From my BP -  I am calling the PubSubBo with a response of arrays that gives me targets in a string array 

- BP then sends to all targets from a call inside a loop of targets array. The target of which is set dynamically from context of the loop element.

This gives me an extra functionality of putting some extra logic but most importantly in Visual Trace it doesn't look odd if target is a BP.
If target is a BP and it is forwarded to, from a normal pubsubBo then in visual trace it shows a backward arrrow which is hard to explain to non tech people as it seems its going backward not forward. So forwarding it to targets from a BP is a better and cleaner option .

Can share code to anyone if needed.

Hi Neerav,

I am working on a production (PubSubService Produciton) that I have exclusively created to manage Publish/Subscriber operations (not business operation). The purpose of my production is to receive the publisher's request, gets its subscriber based on topics and send them a message to perform some updates at subscriber level. I also want to receive an acknowledgement of updates from each subscriber. It would be very help to have your code that you have implemented to get a better architectural understanding.

Thanks in Advance


Example I made aims to make a resusable / generic pub-sub model which is passing a generic json message from start to finish and all bp/bo etc then need to transform / parse as per their own need once they receive the json.  Do let me know if any queries

So this is how the flow works . 
1. Service 
a. Read a csv file, loop through all records
b. In each loop make one json msg and add it to the json array of messages (which is nothing but just an array of text as json is just text)
Property RequestJSONArray As array Of %Text(MAXLEN = 10000);
Property Topic As %String(MAXLEN = 100);

c. End of loop 
Send the array to the BP
This is few lines of code of Service

Class File.BS.FileServiceBS Extends Ens.BusinessService

Parameter ADAPTER = "EnsLib.File.InboundAdapter";

Method OnProcessInput(
pInput As %FileCharacterStream,
pOutput As %RegisteredObject) As %Status
   set DELIMITER = "^"
   set counter=1 //records read
   set JSONDynamicBPRequest = ##class(Ent.Library.JSON.BP.JSONDynamicBPRequest).%New()
   set JSONDynamicBPRequest.Topic = "TESTCSV"
while 'pInput.AtEnd {
   while counter < 3 {
    set line=pInput.ReadLine()
    if ( counter > 1 ) {
    set req = ##class(%DynamicObject).%New()

     set req.ClaimId  = $piece(line,DELIMITER,1)
     set req.Company  = $piece(line,DELIMITER,2)
set req.ClaimProvider  = $piece(line,DELIMITER,3)
set req.PrimaryInsuranceCarrier  = $piece(line,DELIMITER,4)
set req.EncounterDate  = $piece(line,DELIMITER,5)

$$$TRACE("req.%ToJSON() "_req.%ToJSON())
do JSONDynamicBPRequest.RequestJSONArray.SetAt(req.%ToJSON(), counter)

    set counter=counter+1
  do ..SendRequestSync("JSONDynamicBP",JSONDynamicBPRequest)     
  $$$TRACE("JSONDynamicBP loaded : " _ (counter - 1)_" "_$ZDATETIME($ZTIMESTAMP,3,1,6))
  Quit $$$OK


Step 2 : BP
a. Bp gets the topic and json array of json records
b. It calls the PubsubBo to get all the subscribers for this topic
c. It loops through json records
d. for each records. loops through the targets 
e. Sends the message to target via the Call activity of the BP

PFA : Screenshot of subscribers to a topic 
Note :  This can be moulded as per the requirement. Each json msg can have a topic instead of the topic being outside of array etc.
You can use your own messages instead of json too if you need.
You can even send messages via the pubsub bo instead of just getting targets. (version attached)
I mean all sorts of adjustments can be made as this is very generic and re-usable

Link to the Code
Download Code

Any issues pls email me

 Hi Neerav, Have you get a chance to check my email that I sent you a couple of weeks.

Please let me know @Neerav Adam Verma">@Neerav Verma


The Pub/Sub operation only gives you a list of subscribers, you decide what to do with that.

I have a sample of Pub/Sub service/operation, I'll publish it in a few hours.

There is a little modification now what I want to do 

Basicallly I want to read the Event Log (Ens_Util.Log) where type is not in INfo , trace etc

and on every new warning, error etc . send the error msg to my BP - (Which is the pubsub bp)

Is there any service which continously polls for new additions to this log besides the Sql inbound adapter?