Systems: Messaging
E-mail and mailing lists
- Mail can be queued at relays; reliable, but O(days)
- Mlists require subscriber verification; allows digests
USENET News
- Articles, named by message-ID, can be posted to a set of groups within a distribution region until expiry
Publish & Subscribe
- Topic selection can be more specific than “group”, such as selection of characteristics of the messages
Web Push / “Channels”
- Poll for updated content; could be bundled, cached