How NSO removes service-specific configurations from devices?

[santanude2535]

Hi All,

I am new in NSO, I have a generic question about NSO. I am using "nso-5.1.0.1". I create a service (writes some java code) that writes some configurations on two Cisco XR devices as per my requirement.

When I delete that service NSO removes service-specific configurations from both devices. But I don't write any single line of code to remove service-specific configurations from devices. I am curious how NSO determines the delta and removes service-specific configurations from both devices.

Can anyone give me some reference for that?

[ramkraja · Accepted solution]

When I delete that service NSO removes service-specific configurations from both devices. But I don't write any single line of code to remove service-specific configurations from devices. I am curious how NSO determines the delta and removes service-specific configurations from both devices.

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This is really the strength of NSO, and it's FASTMAP algorithm. It lets you specify only the 'create' logic for your service, and takes care of the 'modify' and 'delete' logic itself. See the NSO Development Guide for a description of FASTMAP, here:
"NSO Development Guide -> Developing NSO services -> FASTMAP description"

I would encourage you to read the whole chapter "Developing NSO services".

/Ram

[KJ Rossavik · Accepted solution]

Search for "Fastmap" in the developer guide. This is IMHO the best feature of NSO - this is the "secret sauce". This dramatically reduces the development time and maintenance cost of a service application/function pack relative to other orchestrators.