MESC is a standard for how crypto tools configure their RPC endpoints. By following this specification, a user creates a single RPC configuration that can be shared by all crypto tools on their system.

MESC has two main design goals:

1. make it easy to share RPC configuration data across tools, languages, and environments
2. make it easy to manage the configuration of a large number of RPC endpoints

MESC is formally defined in SPECIFICATION.md.

Additional information can be found in the MESC Documentation.

• Reference Implementations
• Quickstart
• Tutorial
  • Tracked Information
  • Common Interface
  • Typical Usage

Reference implementations are provided for each of the following:

• cli
• go [WIP]
• python
• rust
• typescript [WIP]

These implementations provide a consistent language-agnostic interface while still obeying the best practices of each language.

The quickest way to use MESC is:

1. create a mesc.json config file
2. set the MESC_PATH environment variable to the path of this file

These steps can be performed automatically using the interactive mesc CLI tool:

1. Install: cargo install mesc_cli
2. Perform interactive setup: mesc setup

Installing the mesc cli on some linux distributions may require installing ssl libraries (e.g. sudo apt-get install pkg-config libssl-dev on ubunutu)

Below is a brief tutorial on MESC. For more detail, see the MESC Specification and Documentation.

Topics:

• Tracked Information
• Common Interface
• Typical Usage

MESC tracks the following information:

1. a list of RPC endpoints, including their name, chain_id, and url
2. the default RPC endpoint to use
3. the default RPC endpoint to use for each network

MESC can also track other information like metadata and tool-specific defaults. Configuration data is stored in a JSON file. To create this file, follow the Quickstart instructions above.

All reference MESC implementations use the same common interface.

Here is a comparison between the python interface and the rust interface:

import mesc

# check whether mesc is enabled
enabled: bool = mesc.is_mesc_enabled()

# get the default endpoint
endpoint: Endpoint | None = mesc.get_default_endpoint()

# get the default endpoint of a network
endpoint: Endpoint | None = mesc.get_endpoint_by_network(5)

# get the default endpoint for a particular tool
endpoint: Endpoint | None = mesc.get_default_endpoint(profile='xyz_tool')

# get the default endpoint of a network for a particular tool
endpoint: Endpoint | None = mesc.get_endpoint_by_network(5, profile='xyz_tool')

# get an endpoint by name
endpoint: Endpoint | None = mesc.get_endpoint_by_name('local_goerli')

# parse a user-provided string into a matching endpoint
# (first try 1. endpoint name, then 2. chain id, then 3. network name)
endpoint: Endpoint | None = mesc.get_endpoint_by_query(user_str, profile='xyz_tool')

# find all endpoints matching given criteria
endpoints: list[Endpoint] = mesc.find_endpoints(chain_id=5)

use mesc::{MescError, Endpoint};
use std::collections::HashMap;

type OptionalResult = Result<Option<Endpoint>, MescError>;
type MultiResult = Result<Vec<Endpoint>, MescError>;
type MetadataResult = Result<HashMap<String, serde_json::Value>, MescError>;

// check whether mesc is enabled
let enabled: bool = mesc::is_mesc_enabled();

// get the default endpoint
let endpoint: OptionalResult = mesc::get_default_endpoint(None);

// get the default endpoint of a network
let endpoint: OptionalResult = mesc::get_endpoint_by_network("5", None);

// get the default network for a particular tool
let chain_id: OptionalResult = mesc::get_default_endpoint(Some("xyz_tool"));

// get the default endpoint of a network for a particular tool
let endpoint: OptionalResult = mesc::get_endpoint_by_network("5", Some("xyz_tool"));

// get an endpoint by name
let endpoint: OptionalResult = mesc::get_endpoint_by_name("local_goerli");

// parse a user-provided string into a matching endpoint
// (first try 1. endpoint name, then 2. chain id, then 3. network name)
let user_str = "local_goerli";
let endpoint: OptionalResult = mesc::get_endpoint_by_query(user_str, Some("xyz_tool"));

// find all endpoints matching given criteria
let query = mesc::MultiEndpointQuery::new().chain_id("5").unwrap();
let endpoints: MultiResult = mesc::find_endpoints(query);

Imagine a crypto cli tool xyz. This tool has an argument -r <RPC_URL> that specifies which RPC endpoint to use.

If xyz uses MESC, then -r can become a much more versatile argument. Instead of just accepting a plain URL, -r can accept 1. an endpoint name, 2. chain id, or 3. a network name. Each of the following might resolve to the same RPC url:

• xyz -r localhost:8545 (url)
• xyz -r local_goerli (endpoint name)
• xyz -r 5 (chain id)
• xyz -r goerli (network name)

This url resolution can implemented within xyz using:

# python code used by xyz tool
endpoint = mesc.get_endpoint_by_query(user_input, profile='xyz')
url = endpoint['url']

// rust code used by xyz tool
let endpoint = mesc::get_endpoint_by_query(user_input, Some("xyz"))?;
let url = endpoint.url;