Duration of Mosaics

Technical Discussion
#1

I have been going through the documentation for catapultv2, and while playing around with the java api on https://nemtech.github.io/guides/mosaic.html#lets-get-into-some-code I saw a “duration” parameter while creating the definition transaction. And in the docs (https://nemtech.github.io/concepts/transaction.html#mosaic-definition-transaction) , it says:
“”"
Duration
Renting duration represents the number of confirmed blocks we would like to rent our namespace for.
During the renting period, there is the possibility to extend the rental by sending a RegisterNamespaceTransaction with the extra-confirmed block to rent the namespace.
When a renting period ends, the namespace will become inactive, and you will have N blocks to re-rent it.
“”"

Regarding this part, I am confused… Basically my main questions are

  • How to track if we are getting closer to the initial limit that we set? Are will we get any observable even from the node (like rest of the transactions) to notify/alert us?
  • What happens if we do not re-rent it? All of the mosaics will become useless or they will be just unspendable?

I have tried to find similar topics on forum here, and only similar one is What happen on expiring Mosaic? which is also unanswered till now.
could anyone explain the duration on mosaics (and namespaces as well) or direct me somewhere with details?

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Why block rentals?
#2

Hello,

I asked this questions on Telegram:

cryptoBeliever:
"In mosaic def creation (Catapult) there is new field called duration (https://nemtech.github.io/concepts/transaction.html#mosaic-definition-transaction).
It’s described as: “The number of confirmed blocks we would like to rent our namespace for. Should be inferior or equal to namespace duration.”

  1. I guess it’s typo and should be “would like to rent out mosaic for”
  2. We can decide that mosaic will expire quicker than namespace. This is reason for creation such feature?
  3. This field is required or there is some default like = duration of namespace?
  4. How it works? If we have namespace rent for year. And after half year we creating mosaic then what should I put in duration to ensure it will work as long as namespace?
  5. How it works when we re-rent namespace? Duration for mosaics also changes?
  6. Effect for mosaic is same when mosaic duration ends or mosaic namespace duration ends?"

David 360:
"Mosaic (Catapult Dev Preview) has its own duration property, gaining some independence from namespaces. It is a required field.

Regarding NEM public network, the behaviour (limit it to namespace duration for example) still not final and probably will change. For that reason, there is not so much info about how duration will work in that case.

For further Catapult related questions, please use slack. You will get the link after applying for the early access program."

Your questions:

"

  • How to track if we are getting closer to the initial limit that we set? Are will we get any observable even from the node (like rest of the transactions) to notify/alert us?
  • What happens if we do not re-rent it? All of the mosaics will become useless or they will be just unspendable?
    "

Based on current bahaviour.
If namespace getting closer to expire nanowallet should notify you month before expire date.
If namespace will expire you can do nothing with mosaics for example you can transfer it. Probably they will also not returned by API (I’m not sure). If someone else will buy expired namespace there will be no old mosaics there and new namespace will have same name but other id.

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