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Secrets of the NSO Transaction Phases

Cisco Employee

I've been asked to describe how the NSO transaction processing works countless times, i.e. what happens after the operator hits "commit" until an "ok" or "fail" is received, and the change has been processed by service code, NEDs and possibly commit queues.

For the first time, I've made an attempt to package this information in the form of a presentation rather than on a whiteboard. This is necessarily simplified a little, but I hope this is the level of detail that should be as useful as possible to a wider audience. In case you feel I skipped some aspect that you'd like more information on (HA, preLockCreate, ...), place a request related to this post and I'll think of a way to add a slide.

This presentation should be up to date with respect to the new cool features in NSO 4.4.

[edit: Click the post title to see the blog post in a format where the presentation link is visible]

Cisco Employee

Thanks for putting this up jlindbla, extremely useful. We should make it a poster for developers to put on the wall

Cisco Employee

Thanks a lot jlindbla!  Your work is always useful.

Question - based on your diagram, when are the methods related to the experimental classes Subscriber and TwoPhaseSubscriber called?


Cisco Employee


Subscriber: during Notify on slide 15, look for "custom subscribers"

TwoPhaseSubscriber: first during Prepare on slide 12, look for "custom database", then once more, either during Notify, just like subscriber above, or (if the transaction failed) during Abort on slide 20, look for "custom database"


Thanks for sharing this Jan.