I am working in the SA layer defining the SFs allocated to the System of Interest in a SAB diagram.
When I want to break a SF down, I right-click on the SF and opening a dedicated SFBD. After the breakdown, I would expect the child-SFs to be automatically allocated to the System (i.e., the element which the parent SF is allocated to).
To allocate the child SFs, I must go back to the SAB and execute the allocation manually.
Is my expectation wrong? If yes, which is the rationale for it?
Thanks in advance!
Disclaimer! I’m pretty new here but will share my perspective. It may not be correct and I’m sure you will get responses from others whose feedback you should probably favor over mine.
I think the whole idea of breaking down SF’s is so that you can document what the system of interest should do vs. what other entities should do. If you are allocating a function to the system and then breaking it down, you’re probably decomposing more than you need to at the system level. That could be why Capella doesn’t automatically allocate to the system, it might not be appropriate to assume decomposed SF’s should be allocated.
What I do is look at the system functions that I transitioned from my operational activities in a SDFB and determine if the system will own the function entirely or not. If it will, I can go into the SAB and allocate it directly. If it will not own it at all, I allocated it to one of the entities. If the system will own a part of it, but an entity will own another part, that’s a sign that I need to break the function down. So I decompose it in either the SDFB or in a SFBD (I prefer SDFB). Then, after decomposing, I allocate the appropriate decomposed functions to the system or the entities. The parent function that I decomposed doesn’t get allocated at all in the SAB since it comprises the sub functions and would be redundant to include.
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