How do I automatically reject transactions with specific metadata?

Question

I'm trying to build an application using MultiChain, using it as a append-only archive, as described here. How can I prevent nodes from adding entries with certain metadata? How can I make other nodes reject all transactions containing specific metadata? At least majority of the nodes run same code for validation, so rejecting doesn't create consensus problems.

Answer 1

This is a good question, but unfortunately there is no way currently to do this. We've had quite a few requests relating to filtering transactions for validity so it's something we'll look into enabling in future.

Comments

I'd also love to see this, some kind of hook where a developer could provide a function that would return true/false would be phenomenal.

---

Noted. Could you write this as a plug-in that is compiled?

---

Can you point me at some source or docs on how to write plugins for MultiChain? I'm not seeing anything in my initial look.

---

Sorry for the misunderstanding - it's not possible now, I was just asking if this would be an approach you could work with, so we can plan future versions.

---

Ah, yes -- I think a plugin model would make sense here. I'd think I'd want to be able to define a function that accepted a transaction and as much other context as possible (info on the mining node, maybe some info on the current block or something) and then could make a decision on whether or not to pick up this transaction. I realize you're not open-sourced yet, but out of curiosity, what language would this be in?

---

MultiChain is written in C, so the quickest way would be just to modify the source code in C once it's open. After that, we could have a more formal plugin interface that could work with multiple languages.

---

Okay -- I like the idea of using metadata rather than smart-contracts in transactions, but I'd like some internal mechanism for validation before accepting the transaction (rather than an external process to listen for already-completed transactions and taking compensating actions after-the-fact).

I suppose an alternative would be to effectively "proxy" incoming transactions and forwarding them along to MultiChain only if they meet a given set of criteria.

---

Hi jharris,

I'm curious, any updates on this? Even I was looking for a plugin like this one to be a substitute for smart contracts.

---

The feature, and how it might look, are still under active discussion. But we have no concrete date yet for implementing this.

---

Ok cool, I'll also look into this and see if something could be implemented.