# ICTC

A distributed transaction framework for Defi application on IC network. It supports Motoko language. The core idea of [ICTC](https://github.com/iclighthouse/ICTC) is inspired by the DTC (Distributed Transaction Coordinator), which is commonly used in the financial sector.

Distributed transactions on blockchain networks, like IC-based dapps and DeFi applications, face challenges due to distinct trust assumptions. Unlike traditional systems that trust participating entities, blockchain systems trust only the smart contract code.

For cross-canister calls within a canister, data inconsistency can arise due to callee faults:

1. Business error: like insufficient token balance.
2. Runtime error: such as a divide-by-0 error.
3. Fail-stop: where the callee's subnet becomes inaccessible.

Although the IC network rarely experiences fail-stop, it's crucial for DeFi apps to handle potential failures and ensure eventual consistency, or face severe repercussions.

A new framework, ICTC, rooted in "Base: An Acid Alternative," aims for eventual consistency in cross-canister transactions. However, ICTC only ensures "best-effort delivery" and depends on governance or manual interventions for final consistency.

ICTC mandates: For callee:

* Achieve task atomicity.
* Implement features for eventual consistency:
  * Allow retries with idempotency.
  * Use Nonce for orderly execution and idempotency.
  * Pre-calculate globally unique txid.
  * Offer reversal transaction functions.

For caller:

* Ensure eventual consistency using:
  * Retries.
  * Automatic/manual reversal transactions.
  * "Debit first, credit later" approach.
  * Caller-led coordination.


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