diff --git a/documentation/en/.library.json b/documentation/en/.library.json index 4d348c145..85282779c 100644 --- a/documentation/en/.library.json +++ b/documentation/en/.library.json @@ -143,6 +143,13 @@ "value": null, "posts": [] }, + { + "title": "Payment Channels", + "slug": "en+payment-channels", + "github": "en/payment-channels.md", + "value": null, + "posts": [] + }, { "title": "Command Line Interface", "slug": "en+cli", diff --git a/documentation/en/payment-channels.md b/documentation/en/payment-channels.md new file mode 100644 index 000000000..44f9affd9 --- /dev/null +++ b/documentation/en/payment-channels.md @@ -0,0 +1,86 @@ +# Payment Channels + +Payment channels are used to transfer funds between two actors. + +For example in lotus a payment channel is created when a client wants to fetch data from a provider. +The client sends vouchers for the payment channel, and the provider sends data in response. + +The payment channel is created on-chain with an initial amount. +Vouchers allow the client and the provider to exchange funds incrementally off-chain. +The provider can submit vouchers to chain at any stage. +Either party to the payment channel can settle the payment channel on chain. +After a settlement period (currently 12 hours) either party to the payment channel can call collect on chain. +Collect sends the value of submitted vouchers to the channel recipient (the provider), and refunds the remaining channel balance to the channel creator (the client). + +Vouchers have a lane, a nonce and a value, where vouchers with a higher nonce supersede vouchers with a lower nonce in the same lane. +Each deal is created on a different lane. + +Note that payment channels and vouchers can be used for any situation in which two parties need to incrementally transfer value between each other off-chain. + +## Using the CLI + +For example a client creates a payment channel to a provider with value 10 FIL. + +```sh +$ lotus paych get 10 + +``` + +The client creates a voucher in lane 0 (implied) with nonce 1 (implied) and value 2. + +```sh +$ lotus paych voucher create 2 + +``` + +The client sends the voucher to the provider and the provider adds the voucher to their local store. + +```sh +$ lotus paych voucher add +``` + +The provider sends some data to the client. + +The client creates a voucher in lane 0 (implied) with nonce 2 (implied) and value 4. + +```sh +$ lotus paych voucher create 4 + +``` + +The client sends the voucher to the provider and the provider adds the voucher and sends back more data. +etc. + +The client can add value to the channel after it has been created by calling `paych get` with the same client and provider addresses. + +```sh +$ lotus paych get 5 + # Same address as above. Channel now has 15 +``` + +Once the client has received all their data, they may settle the channel. +Note that settlement doesn't have to be done immediately. +For example the client may keep the channel open as long as it wants to continue making deals with the provider. + +```sh +$ lotus paych settle +``` + +The provider can submit vouchers to chain (note that lotus does this automatically when it sees a settle message appear on chain). +The provider may have received many vouchers with incrementally higher values. +The provider should submit the best vouchers. Note that there will be one best voucher for each lane. + +```sh +$ lotus paych voucher best-spendable + + + + +$ lotus paych voucher submit +``` + +Once the settlement period is over, either the client or provider can call collect to disburse funds. + +```sh +$ lotus paych collect +```