I am new to cryptocurrency development.Today I learned that the ETH transaction requires an RPC server. I found a list of RPC servers like Binance. But is there any official RPC server? Or do you need to create it yourself? What is the difference? Where to get the official exchange rate eth to USD? Many thanks.
There is no official centralised server, because peer-to-peer cryptocurrencies are about decentralisation. Creating single points of failure is bad.
Ethereum software-as-a-service node alternatives can found on:
https://ethereumnodes.com
I also recommend you to try to host the node yourself.
Related
I am new to Ethereum and generally to blockchain. I learned that Ethereum blockchain works on Kademlia. The distributed hash table and its working was beautiful and nicely explained by Eleuth P2P.
Now I used geth to connect to the Ethereum Mainnet and it discovered 2 to 3 maximum peers in 5 to 6 minutes.
Now I know the algorithm but my concern is how the first peer is discovered? Because internet is just a big set of routers and different type of computers (server, computer, etc ) and if you broadcast the discovery like in ARP. The internet will be flooded with these peer discovery broadcast messages and this doesn't seems right. So how initially the connections are made? Also we cannot trust a single network for first time connection because this will make the system server and client based and not decentralised so how the initial connections and peer discovery happens?
Are the broadcast message like have TTL like to prevent the circular loop like in TCP I guess? But this also seems a horrible idea to me.
Please explain.
In order to get going initially, geth uses a set of bootstrap nodes whose endpoints are recorded in the source code.
Source: Geth docs
Here's the list of the bootstrap nodes hardcoded in the Geth source code: https://github.com/ethereum/go-ethereum/blob/v1.10.11/params/bootnodes.go#L23
The --bootnodes option allows you to overwrite this list with your own. Example from the above linked docs:
geth --bootnodes enode://pubkey1#ip1:port1,enode://pubkey2#ip2:port2,enode://pubkey3#ip3:port3
In way to skip the need of trusting a third party and to skip the full download of the blockchain on my PC, I would like to setup a full node syncing an ethereum testnet blockchain on a local server and then connect my PC to this server, using a geth instance.
Is that possible in some way?
How can I do that?
You can just connect to your local geth server via rpc
geth attach http://host:port
There you can read about geth's rpc apis
You can start rpc listener with this command on your geth server after or during syncing
admin.startRPC(host, port, cors, apis)
As an alternative you can just use light sync on your main pc so you won't need to download full blockchain
geth --light
But it depends on what you gonna do with it
For others having problem with syncing. I think it's a good idea [ for development and testing ] to setup the ethereum blockchain locally instead of connecting with any testnet or the mainnet.
Reference:
https://nodejsera.com/blockchain/how-to-start-a-private-ethereum-blockchain-network.html
I'm trying to get my head around blockchain and I'm finding it difficult to get a straight forward answer to this. Say I create a web application that interacts with a blockchain. A user opens my web app, logs in and uses that web application and so a transaction occurs and a new block is added to the chain. How is that blockchain stored on their PC, since the point of blockchain is that it is stored on every participating node? In what format is it stored?
Your web application will interact with the blockchain as a client (likely using one of the Hyperledger Fabric SDKs). The "blocks" will be stored on one or more peer nodes (depending on how many peers are connected to a given channel) not on your client nor on the server hosting your web application.
I'd recommend looking at this to understand the overall transaction flow and this to understand the ledger.
Is their a way to access ethereum Dapps other than the mist browser. I was thinking along the lines of a normal browser like chrome. Also, as a sub question how are some Android and IOS apps connecting to the blockchain?
You can do that through Ethereum JSON-RPC: https://github.com/ethereum/wiki/wiki/JSON-RPC
You have to use
eth_call - read from contract
eth_sendTransaction - send transaction to a contract
You must understand that you'll also need to have an Ethereum node started, most probably with unlocked account to execute transactions from it. Which means you don't want to run it on public networks, but rather in local network. That's what Mist do for you essentially.
Also, take a look at MetaMask, it provides same API for browser based app, but requires an additional plugin to be installed into a browser
What is a client in a network of Hyperledger fabric peer?
What is the role of a client?
What can qualify as a client in the Hyperledger fabric blockchain network?
have a look at this (and specifically, look into the Network Entities / Systems part):
https://github.com/hyperledger/fabric/blob/master/docs/glossary.md
I'm still rather new to this, but my understanding is that you have a) peers in a P2P network that can be either validator or non-validator - the latter existing mostly for performance purposes; and b) you have clients, who talk to peers in a client-server manner to issue queries and request transactions from the P2P network.
What can qualify as a client: basically anything that can talk to peers in this manner. (I think there are even some SDKs, but I'm concentrating on other aspects of Hyperledger, so I don't know yet.) Have a look at the IBM Marbles demo:
https://github.com/IBM-Blockchain/marbles
A client application talks to a peer over either REST or GRPC interface and submits transactions and queries to the peer to chaincodes.
A client is an end user of the application. The client invokes the smart contract by placing a request on the channel. Each smart contract has a set of endorsing pairs required. The request is picked by the required endorsing peers and executed. The resulting read-write sets are sent back to the client.
what is Client in Hyperledger :
The Hyperledger Fabric Client SDK makes it easy to use APIs
to interact with a Hyperledger Fabric blockchain.
Features:
create a new channel
send channel information to a peer to join
install chaincode on a peer
instantiate chaincode in a channel, which involves two steps: propose and transact
submitting a transaction, which also involves two steps: propose and transact
query a chaincode for the latest application state
various query capabilities:
logging utility with a built-in logger (winston)