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ethOnBlock

Name: ethOnBlock
ethOnBlock is a stream of changes in the EVM state when a new block is mined. The stream includes the results of eth_call and other RPC requests provided by users and is restricted based on the number of calls. This is a Gateway-API only stream.
Options
Key
Description
Values
include
Fields to include in the on block event stream
name, response, blockHeight, tag [Default: all]
call-params
Fields used to build an RPC call request
method- see chart below for available methods and additional fields required for each method
tag- latest, 0, or negative number. [Default: 0]
name- unique string identifier for call. [Default: integer counter]
Method
Call Documentation
Additional Fields
eth_call
from, to, gas, value, data
eth_getBalance
address
eth_getTransactionCount
address
eth_getCode
address
eth_getStorageAt
address, pos
eth_blockNumber
None
​

Examples - Websocket

Gateway
Cloud-API
ethOnBlock Event
Subscribing to the ethOnBlock stream via the Gateway-API in Python (Line 6 creates the subscription):
import asyncio, jason, websockets
​
async def main():
async with websockets.connect(ws_uri) as websocket:
payload = {
"jsonrpc": "2.0",
"id": 1,
"method": "subscribe",
"params": [
"ethOnBlock",
{
"include": ["name", "response", "block_height", "tag"],
"call-params": [
{
"name": "my_call_name",
"to": "0xd46e8dd67c5d32be8058bb8eb970870f07244567",
"gas": "0x76c0",
"value": "0x9184e72a",
"data": "0x00"
},
{
"name": "number",
"method": "eth_blockNumber"
}
]
}
]
}
await websocket.send(json.dumps(payload))
subscription_id = await websocket.recv()
while True:
next_notification = await websocket.recv()
print(next_notification) # or process it generally
await websocket.send(json.dumps({"jsonrpc": "2.0", "id": 2, "method": "unsubscribe", "params": [subscription_id]}))
if __name__ == '__main__':
asyncio.get_event_loop().run_until_complete(main())
The ethOnBlock stream is not available via Cloud-API.
TaskCompletedEventis received after all calls have been executed upon receipt of a block.TaskDisabledEvent is received if there is an error response to a call, indicating that the call has been disabled.
Python Gateway:
<<< {'name': 'balance', 'response': {'result': '0x1'}, 'blockHeight': 11654331, 'tag': 11654331}
{'name': 'height', 'response': {'result': '0xb1d4bb'}, 'blockHeight': 11654331, 'tag': 11654331}
{'name': 'TaskDisabledEvent', 'response': {'commandMethod': 'eth_getBalance', 'blockOffset': 0, 'callName': 'balance', 'callPayload': {'address': '0x0000000000000000000000000000000000000000'}, 'active': False}, 'blockHeight': 11654331, 'tag': 11654331}
{'name': 'number', 'response': {'result': '0x0'}, 'blockHeight': 11654331, 'tag': 11654331}
{'name': 'TaskCompletedEvent', 'response': {}, 'blockHeight': 11654331, 'tag': 11654331}}
​
Go Gateway:
<<< {'name': 'balance', 'response': '0x1', 'block_height': 11654331, 'tag': 11654331}
{'name': 'height', 'response': '0xb1d4bb', 'block_height': 11654331, 'tag': 11654331}
{'name': 'TaskDisabledEvent', 'response': '{commandMethod:eth_call blockOffset:0 callName:my_call callPayload:{"data":"0x00","to":"0x0000000000000000000000000000000000000000"} active:false}', 'block_height': '13462626', 'tag': '0xcd6c62'}
{'name': 'number', 'response': '0x0', 'block_height': 11654331, 'tag': 11654331}
{'name': 'TaskCompletedEvent', 'response': '', 'block_height': 11654331, 'tag': 11654331}}
​

Examples - gRPC

Gateway
Subscribing to Gateway ethOnBlock Stream in Go using gRPC.
package main
​
import (
"context"
"fmt"
pb "github.com/bloXroute-Labs/gateway/v2/protobuf"
"google.golang.org/grpc"
"google.golang.org/grpc/credentials/insecure"
"time"
)
​
type blxrCredentials struct {
authorization string
}
​
func (bc blxrCredentials) GetRequestMetadata(ctx context.Context, uri ...string) (map[string]string, error) {
return map[string]string{
"authorization": bc.authorization,
}, nil
}
​
func (bc blxrCredentials) RequireTransportSecurity() bool {
return false
}
​
func main() {
// gRPC server default values
gatewayHostIP := "localhost"
gatewayGRPCPort := 5001
​
// Open gRPC connection to Gateway.
conn, _ := grpc.Dial(
fmt.Sprintf("%v:%v", gatewayHostIP, gatewayGRPCPort),
grpc.WithTransportCredentials(insecure.NewCredentials()),
grpc.WithPerRPCCredentials(blxrCredentials{authorization: "<YOUR-AUTHORIZATION-HEADER>"}),
)
​
// Use the Gateway client connection interface.
client := pb.NewGatewayClient(conn)
​
// create context and defer cancel of context
callContext, cancel := context.WithTimeout(context.Background(), 24*time.Hour)
defer cancel()
​
// Create a subscription using the stream-specific method and request.
stream, _ := client.EthOnBlock(callContext,
&pb.EthOnBlockRequest{
CallParams: []*pb.CallParams{
{
Params: map[string]string{
"name": "balance",
"method": "eth_getBalance",
"address": "0x178B2A...d8E2F4",
},
},
{
Params: map[string]string{
"name": "number",
"method": "eth_blockNumber",
},
},
},
},
)
​
for {
subscriptionNotification, err := stream.Recv()
if err == nil {
fmt.Println(subscriptionNotification) // or process it generally
}
}
}
​

Response (ethOnBlock Event)

TaskCompletedEventis received after all calls have been executed upon receipt of a block.TaskDisabledEvent is received if there is an error response to a call, indicating that the call has been disabled.
<<< name:"number"
response:"0x1cec877"
blockHeight:"0x1cec877"
tag:"0x1cec877"
​
name:"balance"
response:"0x10febdd5766d5b"
blockHeight:"0x1cec877"
tag:"0x1cec877"
​
name:"TaskCompletedEvent"
blockHeight:"0x1cec877"
tag:"0x1cec877"
...