polkadot_sdk_docs/polkadot_sdk/
xcm.rs

1//! # XCM
2//!
3//! XCM, or Cross-Consensus Messaging, is a **language** to communicate **intentions** between
4//! **consensus systems**.
5//!
6//! ## Overview
7//!
8//! XCM is a standard, specification of which lives in the [xcm format repo](https://github.com/paritytech/xcm-format).
9//! It's agnostic both in programming language and blockchain platform, which means it could be used
10//! in Rust in Polkadot, or in Go or C++ in any other platform like Cosmos or Ethereum.
11//!
12//! It enables different consensus systems to communicate with each other in an expressive manner.
13//! Consensus systems include blockchains, smart contracts, and any other state machine that
14//! achieves consensus in some way.
15//!
16//! XCM is executed on a virtual machine called the XCVM.
17//! Scripts can be written with the XCM language, which are often called XCMs, messages or XCM
18//! programs. Each program is a series of instructions, which get executed one after the other by
19//! the virtual machine. These instructions aim to encompass all major things users typically do in
20//! consensus systems. There are instructions on asset transferring, teleporting, locking, among
21//! others. New instructions are added and changes to the XCVM are made via the [RFC process](https://github.com/paritytech/xcm-format/blob/master/proposals/0032-process.md).
22//!
23//! ## In Polkadot SDK
24//!
25//! The Polkadot SDK allows for easily deploying sovereign blockchains from scratch, all very
26//! customizable. Dealing with many heterogeneous blockchains can be cumbersome.
27//! XCM allows all these blockchains to communicate with an agreed-upon language.
28//! As long as an implementation of the XCVM is implemented, the same XCM program can be executed in
29//! all blockchains and perform the same task.
30//!
31//! ## Implementation
32//!
33//! A ready-to-use Rust implementation lives in the [polkadot-sdk repo](https://github.com/paritytech/polkadot-sdk/tree/master/polkadot/xcm),
34//! but will be moved to its own repo in the future.
35//!
36//! Its main components are:
37//! - [`xcm`](::xcm): The definition of the basic types and instructions.
38//! - [`xcm_executor`]: An implementation of the virtual machine to execute instructions.
39//! - [`pallet_xcm`]: A FRAME pallet for interacting with the executor.
40//! - [`xcm_builder`]: A collection of types to configure the executor.
41//! - [`xcm_simulator`]: A playground for trying out different XCM programs and executor
42//!   configurations.
43//!
44//! ## Example
45//!
46//! To perform the very usual operation of transferring assets, the following XCM program can be
47//! used:
48#![doc = docify::embed!("src/polkadot_sdk/xcm.rs", example_transfer)]
49//!
50//! ## Get started
51//!
52//! To learn how it works and to get started, go to the [XCM docs](xcm_docs).
53
54#[cfg(test)]
55mod tests {
56	use xcm::latest::prelude::*;
57
58	#[docify::export]
59	#[test]
60	fn example_transfer() {
61		let _transfer_program = Xcm::<()>(vec![
62			WithdrawAsset((Here, 100u128).into()),
63			BuyExecution { fees: (Here, 100u128).into(), weight_limit: Unlimited },
64			DepositAsset {
65				assets: All.into(),
66				beneficiary: AccountId32 { id: [0u8; 32].into(), network: None }.into(),
67			},
68		]);
69	}
70}
polkadot_sdk_docs/polkadot_sdk/xcm.rs

polkadot_sdk_docs/polkadot_sdk/
xcm.rs
