DApps | My coding steps to learn Decentralized applications | Blockchain library

To execute transactions and/or queries against blockchains you need connections.

1. Infura is an API gateway to main network and some test networks. It supports a subset of web3 interface. When you like to execute a transaction against the Ethereum blockchain you may use infura as connection to the blockchain. So in this case you are not directly connected to Ethereum, but infura has a connection. The Metamask Browser Plugin works with infura.

2. The alternative approach is to have a Ethereum client like geth or parity running on your machine. In this case the Ethereum Client connects to several public nodes of the blockchain and forwards your transactions to the blockchain.

Depending on your architecture and requirements both approaches could be the best solution.

The following scenario can be suggested as the simplest option:

1. We create a smart contract with 3 methods:

• RegistryRequest(bytes32 info_id, bytes32 user_id, string memory public_cert) payeble
• SendInfo(bytes32 info_id, bytes32 user_id, string file_addr)
• GetInfo(bytes32 info_id, bytes32 user_id) view return(string memory retVal)

1. The consumer calls the method RegistryRequest transfers:

• info_id - the identifier of the required data
• user_id - his unique identifier (e-mail, mobile phone, and so on) ()
• public_cert- his public key OpenSSL and attaches a certain amount in Eth to the transaction as payment for the service.

1. Having received the details and payment from the consumer, you:

• create a file with the data he needs
• encrypt this file with the consumer's public key OpenSSL,
• upload it to some web resource or transfer it via IPFS or Ethereum Swarm (or in any other way)
• using the method SendInfo lay out the "address" of the data file (file_addr) in relation to the data and consumer identifiers (info_id, user_id). To pay for the transaction, you use a portion of the amount received from the consumer along with the RegistryRequest.

1. The consumer through the method GetInfo using the data identifier (info_id) and his personal identifier (user_id) receives the "address" of the data file, extracts and decrypts it

2. If the data changes, then their changed state is laid out similarly to point 3

3. After the expiration of the data provision period, you stop releasing their update

More complex solutions can, for example, be discussed with experts for free and simulated on a kekker.com

The proxy is not enough, because web3.js can get block in subscribtion via ws

Also in quorum getting block by number is broken, it accept only hex, however web3.js assume hex as blockhash

Here is my solution

You have a circular import - move the import of the list view into the ready() method of the app config:

I think you should start by making all Truffles Tutorial : https://www.trufflesuite.com/tutorials

The Solidity docs : https://solidity.readthedocs.io

This Kauri article helps too. - https://kauri.io/article/15b95281c17a4954a5278865bbc0f515/v4/remix-ide-your-first-vyper-smart-contract

You have to go deeper to get the text. If you just want the first title :

Hey @BlockChainProgrammer. Thanks for guiding me on how to use the Quorum proxy. It worked.

For this error, Try to upgrade/downgrade your truffle version to v4.1.

Normally start_testnet should be enough as it lets developers to deploy and test their contract on testnet, which I assume is what most developers want. However, there are certain cases where start_localnet is preferable. For example, if you want to use a different genesis for whatever reason (One reaons I can see is that if you want to see how much things cost with different config parameters), or if testnet is unstable, or if you want to run customized nearcore code that maybe incompatible with testnet code.

I am unfamiliar with this type of application (dapp for ethereum client for windows) - so the advice has to be generic I am afraid.

Per-User Files & Registry Settings: In general deploying files to the user profile and HKCU settings is difficult with MSI. As Chris points out it basically just works for the user installing the MSI, unless you actively add constructs to get files copied to all user profiles, and even then it is sort of clunky.

Approaches: I wrote a long answer a long time ago on the subject: Create folder and file on Current user profile, from Admin Profile (long and elaborate, but without any automagic solutions).

Preferred Approach: Before getting involved in too much complexity, the easiest approach is generally to use your application to copy the userprofile files in place for every user on first launch - instead of using the setup to install user-specific files.

This requires that there is a separate application executable to launch, generally via its own shortcut - which it might not be? It generally does not work for addins for example.

• Approach 1: Install template files per-machine and then copy them to each user's userprofile on application launch.

• Approach 2: Alternatively I like to download files directly from a server or database and put in the userprofile - also on first launch.

Apply Updates?: There are ways to ensure that you can re-copy files if there are changes to your templates as described here: http://forum.installsite.net/index.php?showtopic=21552 (Feb 2019 converted to WayBack Machine link).

Errors: The specific problem you report has to do with the need for a per-user registry key path and a RemoveFolder entry for all folders targeting userprofile locations: