5

So I was using the web3 API from the NodeJS 'web3' module very happily and it works very well (it uses HTTP transport AFAIU). But now I want to receive events from the server (without polling), and for that it seems I need to use the subscription API.

However, the documentation I just linked states subscriptions require a full duplex connection. Geth offers such connections in the form of websockets (enable with --ws) and ipc (enabled by default). Fair enough.

But, for the life of me, I cannot find any sample out there of how to connect via IPC/WebSockets. If the documentation included a simple hello world sample of a subscription, it would be rad.

1

you can also use netcat :

➜  ~  nc -U /home/XXX/.ethereum/geth.ipc
{"jsonrpc":"2.0","method":"eth_coinbase","params":[],"id":1}
{"jsonrpc":"2.0","id":1,"result":"0xeeeeeeeeeeeeeeeeeeeeededededede"}
  • how about using nodejs? :) (if you provide js sample that I'll upvote all your 3 answers :) ) – knocte May 19 '16 at 8:23
  • i'm sorry I don't know js libraries well enough for that but I'm pretty sure other will find a way ;) – euri10 May 19 '16 at 8:44
  • @knocte, bribing him? Did you find js sample? if you send me I'll upvote your answers ;) – Ramesh Pareek Mar 6 '18 at 15:00
1

hacking around I connected in python this way, pretty simple:

➜  ~ ipython2
Python 2.7.11+ (default, May  9 2016, 15:54:33)
Type "copyright", "credits" or "license" for more information.

IPython 4.2.0 -- An enhanced Interactive Python.
?         -> Introduction and overview of IPython's features.
%quickref -> Quick reference.
help      -> Python's own help system.
object?   -> Details about 'object', use 'object??' for extra details.

In [1]: import socket

In [3]: s=socket.socket(socket.AF_UNIX,socket.SOCK_STREAM)

In [4]: s.connect("/home/XXX/.ethereum/geth.ipc")

In [5]: message = '{"jsonrpc":"2.0","method":"eth_coinbase","params":[],"id":1}'

In [6]: s.send(message)
Out[6]: 60

In [7]: s.recv(1024)
Out[7]: '{"jsonrpc":"2.0","id":1,"result":"0xeeeeeeeeeeeeeeeeeeeeededededede"}\n'

still browsing it seems this library is designed to do exactly what you want, but in python

0

web3 has providers for IPC and Websockets

http://web3js.readthedocs.io/en/1.0/web3.html#providers

You can use it simply with

const web3 = new Web3(new Web3.providers.IpcProvider(/path/to/.ipc, net))

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