So, recently I got rejected in a Salesforce interview for this question. If we think on this, we will say that pub/sub falls under fire & forget Integration pattern. However, I read it as being marked as a separate pattern in below trailhead module. https://trailhead.salesforce.com/en/content/learn/modules/app-integration-patterns/app-integration-patterns-2

So, I concluded on the basis of this, that it should fall under a separate pattern as here the producer is not aware of the subscriber and there is no acknowledgment sent to the producer. However, when I said the same to the interviewer, he argued with me and seemingly rejected me for this (as checked with HR). I am not saying this as the only reason but as one of the reasons.

Can anyone help me to understand it better or share your view?

If you check below documentation, Salesforce itself has not named it. So, I am confused... https://developer.salesforce.com/docs/atlas.en-us.integration_patterns_and_practices.meta/integration_patterns_and_practices/integ_pat_data_virtualization.htm

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    Does this answer your question? Fire & Forget integration pattern
    – identigral
    Commented Jun 24, 2022 at 16:01
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    In addition to linked Q&A, take a look at Event-Driven Architecture Decision Guide.
    – identigral
    Commented Jun 24, 2022 at 16:01
  • @identigral, I did check both the linked documentations. But still, it is unclear. Can you explain why pub-sub should falls under F&F pattern. The linked documentations say that it falls but don't explain why? This is the point, on which I was not able to justify Interviewer. Commented Jun 24, 2022 at 18:37
  • Also, if we stick to just Salesforce docs (developer.salesforce.com/docs/…), then there is a mention on trailhead (trailhead.salesforce.com/en/content/learn/modules/…) for one more pattern - 'High-Frequency Data Replication'. What about it? Commented Jun 24, 2022 at 18:41
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    HFDR is a class of problems dealing with the transfer of a large number of records or data, just like the sorting algorithms class of algorithms define ways to sort data into a specific order.
    – sfdcfox
    Commented Jun 24, 2022 at 19:33

1 Answer 1


The issue here is that comparing F&F to PubSub is not an "apples-to-apples" comparison. In order to compare two or more things, they should generally be from the same taxonomical parent and have the same taxonomical rank. The answer is simultaneously that F&F and PubSub are the same thing, and yet they are two different things. They share identical characteristics at the "algorithm class" taxonomy level, but there's no way to compare them at the "algorithm" level, because they are in two different taxonomy ranks.

I think the best "correct" answer to such a question is that the question is invalid, because it is incorrect to compare the two directly. Alternatively, you could say that PubSub is an implementation of F&F, so the differences are simply that one is an implementation of an algorithm.

Think about the following hypothetical questions:

  • What's the difference between a vehicle and a car?
  • What's the difference between a laptop and a Lenovo laptop?
  • What's the difference between a rhino and a house?

As you can see, when you don't have an apples-to-apples comparison, the questions simply don't make sense (though, arguably, the last one sounds like a setup for a joke).

As such, in the future, you should take care to avoid such invalid comparisons and point them out. It's entirely possible the interviewer also didn't realize the problem with the question, either, or it might have been a test of logic to see if you could figure out that the question was invalid.

  • Thanks for the explanation. I think it's an unfair comparison. In the broader bucket, it should be F&F but still, it has few capabilities of its own which stand it out... About the interview question, I think it was a bad day. Interviewer having pre-conceived answers to subjective questions is not healthy for the overall candidate assessment. Commented Jun 25, 2022 at 13:57

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