Duplications caused by http/proxy errors

[romantolkachyov]

Why

It is possible that api response will get lost and the accounting client will retry request, so we will get a duplicated transaction.

What

Prevent possible duplications by introducing "nonce" for each transfer. The client should provide unique nonce for each request so we will catch duplicates described above.

How

The option I see is eth-like approach when the client retrieve last nonce from the node for his account, increment it and use incremented value for the next transaction. However, It requires additional api call.

The plan for this option:

• receive and process nonce in transfer handler (+ handle errors)
• add nonce field in the database with unique constraint