[DRAFT] What's the Typical Workflow to Use CKB Open Transaction

[doitian]

Synopsis

First how to start constructing the open transaction?

In my opinion, one party will create an open transaction template. For example, the merchant creates a template that the first input is any cell owned by the merchant locked by Take-All-And-Then, and the first output is a cell with specific address. The template will act the role of address in the simple transfer transaction.

The payer uses an open transaction client to initiate the transaction by taking the template as the input, for example, by scanning the QR code of the template. The client constructs the open transaction from the template by adding payer's cells and signatures and broadcast it to the p2p network.

A service running for the merchant will collect matching open transactions and complete the missing parts. If the transaction need to collect multi-party signatures, the service broadcast the transaction again.

Singers will watch signature requests from the network and sign the transaction after the user approvement.

Roles

• Maker: Who publishes the open transaction template.
• Taker: Who take the template published by Maker and publishes the open transaction to network.
• Builder: The service to collect matched open transactions in the network and create the final transaction or partial signed transaction.
• Signer: The service which watches partial signed transaction and queue the requests to the user. The user approves the request to adds her signature.
• Committer: The service that commits final transaction to CKB. It will re-create the transaction or re-broadcast the open transactions when the commitment fails.

User Stories

Maker Story

As a Maker, I can create a transaction template in the open transaction dApp. I will send the template to my clients, for example, via QR code.

• In the PoC, we will develop the workflow for each dApp separately. Later we'll research whether its possible to create a framework for the open transaction dApps.

Taker Story

As a Taker, I scan the QR code provided by the Maker via the dApp client. The client will collect my live cells, create corresponding outputs, partially sign the transaction, and broadcast it to the open transaction p2p network.

Builder Story

As a Builder, I will watch the p2p network to collect matched open transactions. I'll incrementally build the transaction or join transactions, and then broadcast the outputs to the p2p network.

Signer Story

As a Signer, I will watch the p2p network and create the signing requests queue. If the user approves, I will add the signature and broadcast the outputs to the p2p network.

Committer Story

As a Committer, I will watch the p2p network for open transactions ready to commit. I will generate the final CKB transaction and send it to the CKB node. If the CKB chain accepts the transaction, I will remove the corresponding open transactions, otherwise, I will try to re-create the transaction, or re-broadcast the underlying open transactions.