JSON RPC API

JSON is a lightweight data-interchange format. It can represent numbers, strings, ordered sequences of values, and collections of name/value pairs.

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.

JavaScript API

To talk to an PlatONE node from inside a JavaScript application use the web3.js library, which gives a convenient interface for the RPC methods. See the JavaScript API for more.

JSON-RPC Endpoint

Default JSON-RPC endpoints:

Client	URL
Go	http://localhost:6790

Go

You can start the HTTP JSON-RPC with the --rpc flag

platone --rpc

change the default port (8545) and listing address (localhost) with:

platone --rpc --rpcaddr <ip> --rpcport <portnumber>

If accessing the RPC from a browser, 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:

platone --rpc --rpccorsdomain "http://localhost:3000"

The JSON RPC can also be started from the platone console using the admin.startRPC(addr, port) command.

JSON-RPC support

	PlatONE-Go
JSON-RPC 1.0
JSON-RPC 2.0	✓
Batch requests	✓
HTTP	✓
IPC	✓
WS	✓

HEX value encoding

At present there are two key datatypes that are passed over JSON: unformatted byte arrays and quantities. Both are passed with a hex encoding, however with different requirements to formatting:

When encoding QUANTITIES (integers, numbers): encode as hex, prefix with "0x", the most compact representation (slight exception: zero should be represented as "0x0"). Examples:

• 0x41 (65 in decimal)
• 0x400 (1024 in decimal)
• WRONG: 0x (should always have at least one digit - zero is "0x0")
• WRONG: 0x0400 (no leading zeroes allowed)
• WRONG: ff (must be prefixed 0x)

When encoding UNFORMATTED DATA (byte arrays, account addresses, hashes, bytecode arrays): encode as hex, prefix with "0x", two hex digits per byte. Examples:

• 0x41 (size 1, "A")
• 0x004200 (size 3, "\0B\0")
• 0x (size 0, "")
• WRONG: 0xf0f0f (must be even number of digits)
• WRONG: 004200 (must be prefixed 0x)

Currently cpp-ethereum,go-ethereum and parity provide JSON-RPC communication over http and IPC (unix socket Linux and OSX/named pipes on Windows). Version 1.4 of go-ethereum, version 1.6 of Parity and version 0.8 of Pantheon onwards have websocket support.

The default block parameter

The following methods have an extra default block parameter:

• eth_getBalance
• eth_getCode
• eth_getTransactionCount
• eth_getStorageAt
• eth_call

When requests are made that act on the state of ethereum, the last default block parameter determines the height of the block.

The following options are possible for the defaultBlock parameter:

• HEX String - an integer block number
• String "earliest" for the earliest/genesis block
• String "latest" - for the latest mined block
• String "pending" - for the pending state/transactions

Curl Examples Explained

The curl options below might return a response where the node complains about the content type, this is because the --data option sets the content type to application/x-www-form-urlencoded . If your node does complain, manually set the header by placing -H "Content-Type: application/json" at the start of the call.

The examples also do not include the URL/IP & port combination which must be the last argument given to curl e.x. 127.0.0.1:8545