Stream permissions per key item

Question

Is it possible to have a publicly-writeable stream, but once an item has been published, the key is locked to the original publisher, i.e. other publishers can't write a similar item with the same key?

Answer 1

Not exactly, but you have various APIs that can help apply this logic when retrieving the data. For example, you can easily get just the first item using liststreamkeyitems. To combine all items by the first publisher to key, see the firstpublisher* flags for getstreamkeysummary (MultiChain 2.0).