# `Transport.from` Creates a custom server-side transport. ## Usage ```ts twoslash import { Challenge, Credential, Receipt } from 'mppx' import { Transport } from 'mppx/server' const http = Transport.from({ name: 'http', getCredential(request) { const header = request.headers.get('Authorization') if (!header) return null const payment = Credential.extractPaymentScheme(header) if (!payment) return null return Credential.deserialize(payment) }, respondChallenge({ challenge, error }) { const headers: Record = { 'WWW-Authenticate': Challenge.serialize(challenge), 'Cache-Control': 'no-store', } let body: string | null = null if (error) { headers['Content-Type'] = 'application/problem+json' body = JSON.stringify(error.toProblemDetails(challenge.id)) } return new Response(body, { status: 402, headers }) }, respondReceipt({ receipt, response }) { const headers = new Headers(response.headers) headers.set('Payment-Receipt', Receipt.serialize(receipt)) return new Response(response.body, { status: response.status, statusText: response.statusText, headers, }) }, }) ``` ## Return type ```ts type ReturnType = Transport ``` ## Parameters ### getCredential * **Type:** `(input: Input) => Credential | null` Extracts credential from the transport input. Returns `null` if no credential was provided, or throws if malformed. ### name * **Type:** `string` Transport name for identification. ### respondChallenge * **Type:** `(options: { challenge: Challenge; error?: PaymentError; input: Input }) => ChallengeOutput | Promise` Creates a transport response for a payment challenge. ### respondReceipt * **Type:** `(options: { challengeId: string; receipt: Receipt; response: ReceiptOutput }) => ReceiptOutput` Attaches a receipt to a successful response.