Website to Geth Node – How to connect a website to a geth node

dappsgo-ethereumweb3js

Before the DApp-browser Mist was available, this web3 library seems the way to go on building a bridge from contract to a frontend (web site).

But, I cannot get the very basic examples to work.

These sources lack a few major points:

What is the exact command to start geth to run the examples? I have used:
```
geth --rpc console 2
```
while mining etc.

This example has the line:

web3.setProvider(new web3.providers.HttpProvider());

Should it be localhost?

web3.setProvider(new web3.providers.HttpProvider('http://localhost:8545'));

Is there anyway to hide web3.setProvider and other JavaScript code from the page source viewable for the user? If the geth node address is public, that could be a security problem.

Maybe I'm asking obvious questions here, but it shouldn't be too much trouble to add at least the geth starting argument to the tutorials. The best case scenario would be to have step by step guide with no assumptions left blank.

Best Answer

For point number one, this should work:
geth --rpc --rpccorsdomain="*" console 2>> geth.log
Running --rpccorsdomain="*" is dangerous though, especially if you have unlocked accounts. Put your domain name instead of *. For localhost, add --rpcaddr="localhost"

Related Solutions

[Ethereum] Browser will not connect to running Geth: NS_ERROR_UNKNOWN_PROTOCOL

I fixed it. UI front-end now works, pulling contract data through to the browser.

I was not careful with my port references between geth/cors, http-server, and the one referenced in my UI javascript as Péter Szilágyi sniffed out. I list my working steps below to help others trace similar problems:

First: start geth using: geth --rpc --rpccorsdomain="http://localhost:3000" //presuming the UI will be run on port 3000

Second: Launch the http server on the above referenced port. In my case, used the npm installed module 'http-server': http-server -p 3000 //must match the port referenced in rpccorsdomain above.

Third: Made sure web3 was installed with npm. Linked app.js to index.html and included this code at the top:

 var Web3 = require('web3');

// Initialize connection
 var web3 = new Web3(new Web3.providers.HttpProvider('http://127.0.0.1:8545'));  //may want to test for non-existence first per docs
 var ABI = [...]
 var greeterAddress = "..."
 var greeter = web3.eth.contract(ABI).at(greeterAddress);

[Ethereum] How to connect Dapp front end to geth node

It is not really clear what your understanding of "front-end" is.

In principle any web application that uses the web3.js framework can connect to a geth ethereum node that is running.

You can of course use RPC interface to connect to a running node, but I suspect this is not what you are looking for.

The easiest way to understand what is happening is to install Geth and install Mist.

Mist is an ethereum application that essentially uses the Web3 framework, that allows you to view and create contracts on the public network, the test network, and for the more experienced person their own private networks.

It does this because it can connect automatically to a running geth instance on your local computer, (so whichever it is it will connect toit) or else you can just start it up and if you didn't explicitly start geth it will start that up for you.

Other than Mist - you can build your own front end using web3.js, HTML javascript and CSS.

Best Answer

Related Solutions

[Ethereum] Browser will not connect to running Geth: NS_ERROR_UNKNOWN_PROTOCOL

[Ethereum] How to connect Dapp front end to geth node

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