Interacting with Bitcoin node using RPC
Last updated
Last updated
Through Bitcoin Core RPC Interface, we can interact with a bitcoin node via command line using bitcoin-cli tool. It is also possible to interact programmatically in rust by using bitcoincore_rpc crate.
This crate makes use of crate to interact with the bitcoin node. RPC stands for Remote Procedure Call, which means the client interacts with server using the procedure(function) semantics. The client will specify the function and the inputs required for them in the message to the server and the server returns the result of the function in response.
Rust and C++ are statically typed programming languages, so the compiler itself can help in validating types of inputs for the RPC stubs (similar to endpoints of REST APIs).
It's a wrapper over jsonrpc module's type. This struct has the necessary associated functions to interact with a bitcoin node. There are two fundamental ways to create a value of this struct.
new method expects an Auth parameter which is essentially a wrapper over rpc username and password, it comes with defeault settings of jsonrpc::client::Client type, useful for most of the interactions with a bitcoin node.
from_jsonrpc method expects a value of jsonrpc::client::Client as input, this comes in handy when you require explicit control over how the client interacts with the node.
When to use from_jsonrpc?
If you examine the source code of bitcoincore_rpc::Client, you'll notice that it uses function to create the client with username and password details.
To have customized settings, one has to use function. with_transport function expects as input types which implements , trait defined in the jsonrpc crate. jsonrpc crate re-exports simple_http crate, and it has a , which has methods to create a value of type SimpleHttpTransport with custom timeouts, proxy and authentication settings. The jsonrpc crate has Transport trait implementation for SimpleHttpTransport type, that is Rust allows the programmers to extend the features of a type in a independent crate, rather than modifying the initial source code.
One can also write a implementation of Transport trait for a new type and can make use of the functions written in the jsonrpc crate.
In summary, some bitcoin core rpc calls takes longer time than usual to get the response. If your program requires such calls then using from_jsonrpc function to create the Client is the way to go.
In http, in URI you specify the resource, in the request body you specify some data. REST API end point, you pass data to the endpoint.
RPC endpoints are treated like a function and you pass data like inputs.
crate has a bunch of type definitions for data-strucutres like block, transaction etc., bitcoincore_rpc crate re-uses bitcoin crate wherever possible. bitcoincore_rpc crate uses serde crate to deserialize the json response into corresponding rust types defined in bitcoin crate and other specific types in bitcoincore_rpc crate itself.
bitcoin crates module has the support to serialize a bitcoin type to consensus consistent byte of hex encoding and, deseriazing from a hex or byte format to rust specific types defined in the crate.
In this module you've learnt how to read and send message to a bitcoin node through bitcoin core's rpc interface using rust. Creating more involved messages like crafting a transaction, exporting data to a wallet etc., requires a dive deep into the bitcoin crate, which we will do in . It is also possible to communicate with a bitcoin node through TCP, which gives us more flexibility. Basics of it will be covered in .