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JSON RPC and API

JSON-RPC API

โ€‹JSON is a lightweight data-interchange format. It can represent numbers, strings, ordered sequences of values, and collections of name/value pairs.
โ€‹JSON-RPC is a stateless, light-weight remote procedure call (RPC) protocol. Primarily this specification defines several data structures and the rules around their processing. It is transport agnostic in that the concepts can be used within the same process, over sockets, over HTTP, or in many various message passing environments. It uses JSON (RFC 4627) as data format.

JSON-RPC Support

Echelon supports all standard Web3 JSON-RPC APIs.
JSON-RPC is provided on multiple transports. Echelon supports JSON-RPC over HTTP and WebSocket. Transports must be enabled through command-line flags or through the app.toml configuration file. For more details see below.
Ethereum JSON-RPC APIs use a name-space system. RPC methods are grouped into several categories depending on their purpose. All method names are composed of the namespace, an underscore, and the actual method name within the namespace. For example, the eth_call method resides in the eth namespace.
Access to RPC methods can be enabled on a per-namespace basis.

Defining Namespaces

Eth,Net and Web3 namespaces are enabled by default. In order to enable other namespaces use flag --json-rpc.api.
echelond start --json-rpc.api eth,txpool,personal,net,debug,web3,miner

CORS

If accessing the RPC from a browser and if you do not put the RPC behind a reverse proxy, CORS will need to be enabled with the appropriate domain set. Otherwise, JavaScript calls are limit by the same-origin policy and requests will fail.
The CORS setting can be updated from the app.toml
###############################################################################
### API Configuration ###
###############################################################################
โ€‹
[api]
โ€‹
# ...
โ€‹
# EnableUnsafeCORS defines if CORS should be enabled (unsafe - use it at your own risk).
enabled-unsafe-cors = true # default false

Echelon EVM Websocket

Since Echelon runs using Tendermint Core as it's consensus engine and it's built with the Cosmos SDK framework, it inherits the event format from them. However, in order to support the native Web3 compatibility for websockets of the Ethereum's PubSubAPI (opens new window), Echelon needs to cast the Tendermint responses retrieved into the Ethereum types.
You can start a connection with the Ethereum websocket using the --json-rpc.ws-address flag when starting the node (default "0.0.0.0:8546"):
echelond start --json-rpc.address"0.0.0.0:8545" --json-rpc.ws-address="0.0.0.0:8546" --evm.rpc.api="eth,web3,net,txpool,debug" --json-rpc.enable
Then, start a websocket subscription with ws(opens new window)โ€‹
Connect to JSON RPC tendermint websocket at port 8546 as defined above:
ws ws://localhost:8546/
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On this page
JSON-RPC API
JSON-RPC Support
Defining Namespaces
CORS
Echelon EVM Websocket