# Server \[Protect endpoints with payment requirements] Create an `Mpp` handler with `Mpp.create()` and call `charge()` with a human-readable amount. The `Mpp::Methods::Tempo.tempo()` factory creates a Tempo payment method—configure `currency` and `recipient` once, then every `charge()` call uses those defaults. ## Quick start ```ruby [server.rb] require "mpp-rb" server = Mpp.create( method: Mpp::Methods::Tempo.tempo( currency: "0x20c0000000000000000000000000000000000000", intents: { "charge" => Mpp::Methods::Tempo::ChargeIntent.new }, recipient: "0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266", ), secret_key: ENV["MPP_SECRET_KEY"], ) result = server.charge( request.get_header("HTTP_AUTHORIZATION"), "0.50", description: "Paid resource", ) if result.is_a?(Mpp::Challenge) resp = Mpp::Server::Decorator.make_challenge_response(result, server.realm) [resp["status"], resp["headers"], [resp["body"]]] else credential, receipt = result [200, { "Payment-Receipt" => receipt.to_payment_receipt }, [{ data: "paid content", payer: credential.source }.to_json]] end ``` `Mpp.create()` auto-detects `realm` from environment variables (`FLY_APP_NAME`, `HEROKU_APP_NAME`, `VERCEL_URL`, and others). It reads `MPP_SECRET_KEY` from the environment unless you pass `secret_key` explicitly: ```ruby [server.rb] server = Mpp.create( method: Mpp::Methods::Tempo.tempo( currency: "0x20c0000000000000000000000000000000000000", intents: { "charge" => Mpp::Methods::Tempo::ChargeIntent.new }, recipient: "0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266", ), realm: "api.example.com", secret_key: "my-server-secret", ) ``` ## `Mpp::Methods::Tempo.tempo()` factory `tempo()` creates a method that bundles a payment network, its intents, and default parameters together. Each intent must be explicitly registered via the `intents` parameter. ```ruby [server.rb] method = Mpp::Methods::Tempo.tempo( currency: "0x20c0000000000000000000000000000000000000", recipient: "0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266", intents: { "charge" => Mpp::Methods::Tempo::ChargeIntent.new }, ) ``` ### `tempo()` parameters ### currency (optional) * **Type:** `String` Default TIP-20 token address for charges. ### decimals (optional) * **Type:** `Integer` * **Default:** `6` Token decimal places for amount conversion (6 for pathUSD). ### intents * **Type:** `Hash` Intents to register (for example, `"charge"`). Each intent must be explicitly provided. ### recipient (optional) * **Type:** `String` Default recipient address for charges. ### rpc\_url (optional) * **Type:** `String` * **Default:** `"https://rpc.tempo.xyz"` Tempo RPC endpoint URL. ## `Mpp.create()` parameters ### method * **Type:** `Method` Payment method instance returned by `tempo()`. ### realm (optional) * **Type:** `String` Server realm for `WWW-Authenticate` headers. Auto-detected from environment if omitted. ### secret\_key (optional) * **Type:** `String` HMAC secret for stateless Challenge ID verification. Reads `MPP_SECRET_KEY` if omitted. ## `charge()` parameters ### amount * **Type:** `String` Payment amount in human-readable units (for example, `"0.50"` for $0.50). Automatically converted to base units using the method's decimal precision (6 decimals for pathUSD). ### authorization * **Type:** `String | nil` The `Authorization` header value from the incoming request. ### currency (optional) * **Type:** `String` Override the method's default currency address. ### description (optional) * **Type:** `String` Human-readable description attached to the Challenge. ### expires (optional) * **Type:** `String` Challenge expiration as ISO 8601 timestamp. Defaults to 5 minutes from now. ### recipient (optional) * **Type:** `String` Override the method's default recipient address. ### memo (optional) * **Type:** `String` Memo for memo-enabled transfers. ### fee\_payer (optional) * **Type:** `Boolean` * **Default:** `false` Enable fee sponsorship for this charge. ## Rack middleware Use `Mpp::Server::Middleware` to add payment requirements to any Rack application: ```ruby [config.rb] require "mpp-rb" handler = Mpp.create( method: Mpp::Methods::Tempo.tempo( currency: "0x20c0000000000000000000000000000000000000", intents: { "charge" => Mpp::Methods::Tempo::ChargeIntent.new }, recipient: "0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266", ), ) use Mpp::Server::Middleware, handler: handler ``` In your application, signal that a request requires payment by setting `env["mpp.charge"]`: ```ruby env["mpp.charge"] = { amount: "0.50", description: "Premium endpoint" } ``` The middleware intercepts the response, returns a `402` Challenge on the first request, then processes the Credential on retry. ## Fee sponsorship Sponsor gas fees so clients do not need native tokens. Pass a `fee_payer` account in the Tempo method: ```ruby [server.rb] fee_payer = Mpp::Methods::Tempo::Account.from_env("FEE_PAYER_KEY") method = Mpp::Methods::Tempo.tempo( currency: "0x20c0000000000000000000000000000000000000", recipient: "0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266", intents: { "charge" => Mpp::Methods::Tempo::ChargeIntent.new }, fee_payer: fee_payer, ) ``` When fee sponsorship is enabled, the server co-signs transactions and covers gas fees on behalf of the client.