@trezoa/rpc-spec

This package contains types that describe the implementation of the JSON RPC API, as well as methods to create one. It can be used standalone, but it is also exported as part of Kit @trezoa/kit.

This API is designed to be used as follows:

const rpc =
    // Step 1 - Create a `Rpc` instance. This may be stateful.
    createTrezoaRpc(mainnet('https://api.mainnet-beta.trezoa.com'));
const response = await rpc
    // Step 2 - Call supported methods on it to produce `PendingRpcRequest` objects.
    .getLatestBlockhash({ commitment: 'confirmed' })
    // Step 3 - Call the `send()` method on those pending requests to trigger them.
    .send({ abortSignal: AbortSignal.timeout(10_000) });

Types

PendingRpcRequest<TResponse>

Pending requests are the result of calling a supported method on a Rpc object. They encapsulate all of the information necessary to make the request without actually making it.

Calling the send(options) method on a PendingRpcRequest<TResponse> will trigger the request and return a promise for TResponse.

Rpc<TRpcMethods, TRpcTransport>

An object that exposes all of the functions described by TRpcMethods. Calling each method returns a PendingRpcRequest<TResponse> where TResponse is that method's response type.

RpcApi<TRpcMethods>

For each of TRpcMethods, this object exposes a method with the same name that maps between its input arguments and a RpcPlan<TResponse> that implements the execution of a JSON RPC request to fetch TResponse.

RpcPlan

This type allows an RpcApi to describe how a particular request should be issued to the JSON RPC server. Given a function that was called on a Rpc, this object exposes an execute function that dictates which request will be sent, how the underlying transport will be used, and how the responses will be transformed.

This function accepts a RpcTransport and an AbortSignal and asynchronously returns a RpcResponse. This gives us the opportunity to:

• define the payload from the requested method name and parameters before passing it to the transport.
• call the underlying transport zero, one or multiple times depending on the use-case (e.g. caching or aggregating multiple responses).
• transform the response from the JSON RPC server, in case it does not match the TResponse specified by the PendingRpcRequest<TResponse> returned from that function.

RpcSendOptions

A configuration object consisting of the following properties:

• abortSignal: An optional signal that you can supply when triggering a PendingRpcRequest that you might later need to abort.

RpcTransport

Any function that implements this interface can act as a transport for a Rpc. It need only return a promise for a response given the following config:

• payload: A value of arbitrary type to be sent.
• signal: An optional AbortSignal on which the 'abort' event will be fired if the request should be cancelled.

Functions

createRpc(config)

Creates a Rpc instance given an RpcApi<TRpcMethods> and a RpcTransport capable of fulfilling them.

Arguments

A config object with the following properties:

• api: An instance of RpcApi
• transport: A function that implements the RpcTransport interface

createJsonRpcApi(config)

Creates a JavaScript proxy that converts any function call called on it to a RpcPlan by creating an execute function that:

• sets the transport payload to a JSON RPC v2 payload object with the requested methodName and params properties, optionally transformed by config.requestTransformer.
• transforms the transport's response using the config.responseTransformer function, if provided.

// For example, given this `RpcApi`:
const rpcApi = createJsonRpcApi({
    requestTransformer: (...rawParams) => rawParams.reverse(),
    responseTransformer: response => response.result,
});

// ...the following function call:
rpcApi.foo('bar', { baz: 'bat' });

// ...will produce an `RpcPlan` that:
// -   Uses the following payload: { id: 1, jsonrpc: '2.0', method: 'foo', params: [{ baz: 'bat' }, 'bar'] }.
// -   Returns the "result" property of the RPC response.

Arguments

A config object with the following properties:

• requestTransformer<T>(request: RpcRequest<T>): RpcRequest: An optional function that transforms the RpcRequest before it is sent to the JSON RPC server.
• responseTransformer<T>(response: RpcResponse, request: RpcRequest): RpcResponse<T>: An optional function that transforms the RpcResponse before it is returned to the caller.

isJsonRpcPayload(payload)

A helper function that returns true if the given payload is a JSON RPC v2 payload. This means, the payload is an object such that:

• It has a jsonrpc property with a value of '2.0'.
• It has a method property that is a string.
• It has a params property of any type.

import { isJsonRpcPayload } from '@trezoa/rpc-spec';

if (isJsonRpcPayload(payload)) {
    const payloadMethod: string = payload.method;
    const payloadParams: unknown = payload.params;
}