Ethereum node query

1. At the top of Ethereum is DAPP. It exchanges with the smart contract layer through Web3. JS. All smart contracts run on EVM (Ethereum virtual machine) and use RPC calls. Below EVM and RPC are the four core contents of Ethereum, including: blockchain, consensus algorithm, mining and network layer. Except DAPP, all other parts are in the Ethereum client. The most popular Ethereum client is geth (go Ethereum)

2.

If you want to query the transaction records on the main network, you can use Etherscan. However, if you build your own private chain, how should you query the transaction records

the answer is that you need to listen to the logs on the chain, save them in the database, and then query them in the database. For example:

< pre t = "code" L = "Java" > varaddr = & quot& quot;< br />varfilter=web3.eth.filter({fromB lock:0 ,toBlock:' latest', address:addr });< br />filter.get(function(err,transactions){
transactions.forEach(function(tx){
vartxInfo=web3.eth.getTransaction(tx.transactionHash);
/ / at this time, the transaction information txinfo can be stored in the database
})< br />});

Web3. Eth. Filter() is used to monitor the log on the chain, and Web3. Eth. Gettransaction() is used to extract the information of the specified transaction. Once the transaction information is obtained, it can be stored in the database for query

recommend a practical introction, you can see: Ethereum tutorial

3. Just focus:
you can't retrieve your assets through Ethereum block query
think too much
if you want to check the real estate,

you can go to the real estate transaction registration center.

4. Generally speaking, undefined index is the exact writing problem in the process of writing. Notice generally prompts for errors that are not directly related to the execution of code, but don't forget that notice sometimes returns some rendant error information

5. How many account addresses can an Ethereum node have at most
A: generally, there is only one account address, otherwise there will be an error! Blockchain itself is unique. If there are multiple account addresses on one node, it violates the fundamental principle of blockchain!

6. The withdrawal of digital currency generally only occurs on the digital currency trading platform. Where to withdraw cash? It is suggested to check the account number of the accounting platform carefully. It is generally in the personal center. The specific situation still needs to consult the official personnel, and the answer given by the official shall prevail. However, when choosing a digital currency trading platform, it is better to choose a big platform such as Xigu digital asset trading platform and bitcoin China.

7. There is no problem at all, but relatively speaking, we must buy some reliable ones, because we must pay attention to them.

8. < UL >

try to set your TCP / IP protocol to automatic acquisition state. Method: right click Network Neighborhood - properties - right click & quot; Local connection & quot; Properties - double click & quot; Internet Protocol TCP / IP & quot- IPX is the bottom layer protocol of NetWare. It is only responsible for the movement of data in the network. It does not guarantee the success of data transmission, nor does it provide error correction