neo-go/docs/rpc.md

RPC

Client

Client is provided as a Go package, so please refer to the relevant godocs page.

Server

The server is written to support as much of the JSON-RPC 2.0 Spec as possible. The server is run as part of the node currently.

Example call

An example would be viewing the version of the node:

$ curl -X POST -d '{"jsonrpc": "2.0", "method": "getversion", "params": [], "id": 1}' http://localhost:20332

which would yield the response:

{
  "result" : {
    "useragent" : "/NEO-GO:0.97.2/",
    "tcpport" : 10333,
    "network" : 860833102,
    "nonce" : 105745208
  },
  "jsonrpc" : "2.0",
  "id" : 1
}

Supported methods

Method
calculatenetworkfee
findstates
getapplicationlog
getbestblockhash
getblock
getblockcount
getblockhash
getblockheader
getblockheadercount
getcandidates
getcommittee
getconnectioncount
getcontractstate
getnativecontracts
getnep11balances
getnep11properties
getnep11transfers
getnep17balances
getnep17transfers
getnextblockvalidators
getpeers
getproof
getrawmempool
getrawtransaction
getstate
getstateheight
getstateroot
getstorage
gettransactionheight
getunclaimedgas
getversion
invokecontractverify
invokefunction
invokescript
sendrawtransaction
submitblock
submitoracleresponse
terminatesession
traverseiterator
validateaddress
verifyproof

Implementation notices

JSON representation of enumerations

C# implementation contains a number of enumerations and while it outputs them into JSON as comma-separated strings (or just strings if only one value is allowed for this type) it accepts pure numbers for input (see #2563 for example). NeoGo currently doesn't support this behavior. This affects the following data types:

• transaction attribute type
• oracle response code
• transaction witness scope
• rule witness action
• condition rule witness type
• function call flag
• function call parameter type
• execution trigger type
• stack item type

Any call that takes any of these types for input in JSON format is affected.

Response error codes

NeoGo currently uses a different set of error codes in comparison to C# implementation, see proposal. NeoGo retains certain deprecated error codes, which will be removed once all nodes adopt the new error standard.

calculatenetworkfee

NeoGo tries to cover more cases with its calculatenetworkfee implementation, whereas C# node support only standard signature contracts and deployed contracts that can execute verify successfully on incomplete (not yet signed properly) transaction, NeoGo also works with deployed contracts that fail at this stage and executes non-standard contracts (that can fail too). It's ignoring the result of any verification script (since the method calculates fee and doesn't care about transaction validity). Invocation script is used as is when provided, but absent it the system will try to infer one based on the verify method signature (pushing dummy signatures or hashes). If signature has some types which contents can't be adequately guessed (arrays, maps, interop, void) they're ignored. See neo-project/neo#2805 as well.

invokefunction, invokescript

neo-go implementation of invokefunction does not return tx field in the answer because that requires signing the transaction with some key in the server, which doesn't fit the model of our node-client interactions. If this signature is lacking, the transaction is almost useless, so there is no point in returning it.

It's possible to use invokefunction not only with a contract scripthash, but also with a contract name (for native contracts) or a contract ID (for all contracts). This feature is not supported by the C# node.

If iterator is present on stack after function or script invocation then, depending on SessionEnable RPC-server setting, iterator either will be marshalled as iterator ID (corresponds to SessionEnabled: true) or as a set of traversed iterator values up to DefaultMaxIteratorResultItems packed into array (corresponds to SessionEnabled: false).

getcontractstate

It's possible to get non-native contract state by its ID, unlike with C# node where it only works for native contracts.

getrawtransaction

VM state is included into verbose response along with other transaction fields if the transaction is already on chain.

getstateroot

This method is able to accept state root hash instead of index, unlike the C# node where only index is accepted.

getstorage

This method doesn't work for the Ledger contract, you can get data via regular getblock and getrawtransaction calls. This method is able to get storage of a native contract by its name (case-insensitive), unlike the C# node where it only possible for index or hash.

getnep11balances and getnep17balances

neo-go implementation of getnep11balances and getnep17balances does not perform tracking of NEP-11 and NEP-17 balances for each account as it is done in the C# node. Instead, a neo-go node maintains a list of standard-compliant contracts, i.e. those contracts that have NEP-11 or NEP-17 declared in the supported standards section of the manifest. Each time balances are queried, the neo-go node asks every NEP-11/NEP-17 contract for the account balance by invoking balanceOf method with the corresponding args. Invocation GAS limit is set to be 3 GAS. All non-zero balances are included in the RPC call result.

Thus, if a token contract doesn't have proper standard declared in the list of supported standards but emits compliant NEP-11/NEP-17 Transfer notifications, the token balance won't be shown in the list of balances returned by the neo-go node (unlike the C# node behavior). However, transfer logs of such tokens are still available via respective getnepXXtransfers RPC calls.

The behavior of the LastUpdatedBlock tracking for archival nodes as far as for governing token balances matches the C# node's one. For non-archival nodes and other NEP-11/NEP-17 tokens, if transfer's LastUpdatedBlock is lower than the latest state synchronization point P the node working against, LastUpdatedBlock equals P. For NEP-11 NFTs LastUpdatedBlock is equal for all tokens of the same asset.

getversion

NeoGo can return additional fields in the protocol object depending on the extensions enabled. Specifically that's p2psigextensions and staterootinheader booleans and committeehistory and validatorshistory objects (that are effectively maps from stringified integers to other integers. These fields are only returned when corresponding settings are enabled in the server's protocol configuration.

getnep11transfers and getnep17transfers

transfernotifyindex is not tracked by NeoGo, thus this field is always zero.

traverseiterator and terminatesession

NeoGo returns an error when it is unable to find a session or iterator, unlike the error-free C# response that provides a default result.

verifyProof

NeoGo can generate an error in response to an invalid proof, unlike the error-free C# implementation.

Unsupported methods

Methods listed below are not going to be supported for various reasons and we're not accepting issues related to them.

Method	Reason
closewallet	Doesn't fit neo-go wallet model
dumpprivkey	Shouldn't exist for security reasons, see closewallet comment also
getnewaddress	See closewallet comment, use CLI to do that
getwalletbalance	See closewallet comment, use getnep17balances for that
getwalletunclaimedgas	See closewallet comment, use getunclaimedgas for that
importprivkey	Not applicable to neo-go, see closewallet comment
listaddress	Not applicable to neo-go, see closewallet comment
listplugins	neo-go doesn't have any plugins, so it makes no sense
openwallet	Doesn't fit neo-go wallet model
sendfrom	Not applicable to neo-go, see openwallet comment
sendmany	Not applicable to neo-go, see openwallet comment
sendtoaddress	Not applicable to neo-go, see claimgas comment

Extensions

Some additional extensions are implemented as a part of this RPC server.

getblocksysfee call

This method returns cumulative system fee for all transactions included in a block. It can be removed in future versions, but at the moment you can use it to see how much GAS is burned with a particular block (because system fees are burned).

invokecontractverifyhistoric, invokefunctionhistoric and invokescripthistoric calls

These methods provide the ability of historical calls and accept block hash or block index or stateroot hash as the first parameter and the list of parameters that is the same as of invokecontractverify, invokefunction and invokescript correspondingly. The historical call assumes that the contracts' storage state has all its values got from MPT with the specified stateroot (or, which is the same, with the stateroot of the block of the specified height) and the transaction will be invoked using interop context with block which is next to the block with the specified height. This allows to perform test invocation using the specified past chain state. These methods may be useful for debugging purposes.

Behavior note: any historical RPC call need the historical chain state to be presented in the node storage, thus if the node keeps only latest MPT state the historical call can not be handled properly.The historical calls only guaranteed to correctly work on archival node that stores all MPT data. If a node keeps the number of latest states and has the GC on (this setting corresponds to the RemoveUntraceableBlocks set to true), then the behaviour of historical RPC call is undefined. GC can always kick some data out of the storage while the historical call is executing, thus keep in mind that the call can be processed with RemoveUntraceableBlocks only with limitations on available data.

submitnotaryrequest call

This method can be used on P2P Notary enabled networks to submit new notary payloads to be relayed from RPC to P2P.

Limits and paging for getnep11transfers and getnep17transfers

getnep11transfers and getnep17transfers RPC calls never return more than 1000 results for one request (within the specified time frame). You can pass your own limit via an additional parameter and then use paging to request the next batch of transfers.

An example of requesting 10 events for address NbTiM6h8r99kpRtb428XcsUk1TzKed2gTc within 0-1600094189000 timestamps:

{ "jsonrpc": "2.0", "id": 5, "method": "getnep17transfers", "params":
["NbTiM6h8r99kpRtb428XcsUk1TzKed2gTc", 0, 1600094189000, 10] }

Get the next 10 transfers for the same account within the same time frame:

{ "jsonrpc": "2.0", "id": 5, "method": "getnep17transfers", "params":
["NbTiM6h8r99kpRtb428XcsUk1TzKed2gTc", 0, 1600094189000, 10, 1] }

Websocket server

This server accepts websocket connections on ws://$BASE_URL/ws address. You can use it to perform regular RPC calls over websockets (it's supposed to be a little faster than going regular HTTP route) and you can also use it for additional functionality provided only via websockets (like notifications).

Notification subsystem

Notification subsystem consists of two additional RPC methods (subscribe and unsubscribe working only over websocket connection) that allow to subscribe to various blockchain events (with simple event filtering) and receive them on the client as JSON-RPC notifications. More details on that are written in the notifications specification.

Reference

• JSON-RPC 2.0 Specification
• Neo JSON-RPC 2.0 docs