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60 lines
2.2 KiB
Markdown
60 lines
2.2 KiB
Markdown
NIP-40
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======
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Expiration Timestamp
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-----------------------------------
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`draft` `optional` `author:0xtlt`
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The `expiration` tag enables users to specify a unix timestamp at which the message SHOULD be considered expired (by relays and clients) and SHOULD be deleted by relays.
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#### Spec
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```
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tag: expiration
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options:
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- [UNIX timestamp in seconds]: required
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```
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#### Example
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```json
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{
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"pubkey": "<pub-key>",
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"created_at": 1000000000,
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"kind": 1,
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"tags": [
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["expiration", "1600000000"]
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],
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"content": "This message will expire at the specified timestamp and be deleted by relays.\n",
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"id": "<event-id>"
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}
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```
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Note: The timestamp should be in the same format as the created_at timestamp and should be interpreted as the time at which the message should be deleted by relays.
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Client Behavior
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---------------
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Clients SHOULD use the `supported_nips` field to learn if a relay supports this NIP. Clients SHOULD NOT send expiration events to relays that do not support this NIP.
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Clients SHOULD ignore events that have expired.
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Relay Behavior
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--------------
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Relays MAY NOT delete an expired message immediately on expiration and MAY persist them indefinitely.
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Relays SHOULD NOT send expired events to clients, even if they are stored.
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Relays SHOULD drop any events that are published to them if they are expired.
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Relays SHOULD persist ephemeral events until their expiration timestamp if an ephemeral event has one, and relays MAY limit the amount of time an ephemeral event is persisted.
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Suggested Use Cases
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-------------------
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* Temporary announcements - This tag can be used to make temporary announcements. For example, an event organizer could use this tag to post announcements about an upcoming event.
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* Limited-time offers - This tag can be used by businesses to make limited-time offers that expire after a certain amount of time. For example, a business could use this tag to make a special offer that is only available for a limited time.
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#### One last time, be careful!
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The events could be downloaded by third parties as they are publicly accessible all the time on the relays.
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So don't consider expiring messages as a security feature for your conversations or other uses.
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