Eric Traub [Eric Traub] - Learn Blockchain Programming with JavaScript

Let's refactor the /mine endpoint by implementing the following steps:

1. Head over to the dev/networkNode.js file. In the /mine endpoint, beneath the part where we had defined the newBlock variable, let's add the functionality to broadcast the new block to all the other nodes in the network. To do this, follow the same process that we introduced in the previous sectionsthat is, to loop through all the other nodes inside the network, make a request to the nodes, and send the newBlock variable as data:

bitcoin.networkNodes.forEach(networkNodeUrl => {
})

The preceding line mentions that for each of the networkNodes, we're going to make a request and send along the newBlock.

1. We then need some request options to send. These options will be defined as follows:

bitcoin.networkNodes.forEach(networkNodeUrl => {
const requestOptions = {
};
})

1. The first option in this object is the uri. The uri to which we want to send the request will be the networkNodeUrl and the new endpoint that we are going to create, which will be /receive-new-block. We'll work on this endpoint in the next section:

bitcoin.networkNodes.forEach(networkNodeUrl => {
const requestOptions = {
uri: networkNodeUrl + '/ receive-new-block',
};
})

1. The next option to be added is the method that will be used, which is the POST method:

bitcoin.networkNodes.forEach(networkNodeUrl => {
const requestOptions = {
uri: networkNodeUrl + '/ receive-new-block',
method: 'POST',

};
})

1. Next, let's send along the data that will be inside the body. We also want to send along a newBlock instance:

bitcoin.networkNodes.forEach(networkNodeUrl => {
const requestOptions = {
uri: networkNodeUrl + '/ receive-new-block',
method: 'POST',
body: { newBlock: newBlock }
};
})

1. Finally , after the body , set json to true, as follows:

bitcoin.networkNodes.forEach(networkNodeUrl => {
const requestOptions = {
uri: networkNodeUrl + '/ receive-new-block',
method: 'POST',
body: { newBlock: newBlock },
json: true
};
})

1. After that, make the request by adding the following highlighted line of code:

bitcoin.networkNodes.forEach(networkNodeUrl => {
const requestOptions = {
uri: networkNodeUrl + '/ receive-new-block',
method: 'POST',
body: { newBlock: newBlock },
json: true
};
rp(requestOptions)
})

1. Every time one of these requests is made, it's going to return a promise. Let's make an array of all of these promises by adding the following highlighted code:

const requestPromises = [];
bitcoin.networkNodes.forEach(networkNodeUrl => {
const requestOptions = {
uri: networkNodeUrl + '/ receive-new-block',
method: 'POST',
body: { newBlock: newBlock },
json: true
};
requestPromises.push(rp(requestOptions));
});

After our forEach loop has run, we should have an array that is filled with promises.

1. Next, let's run all of those promises. Therefore, after the forEach block, add the following code:

Promise.all(requestPromises)
.then(data => {
// ....
})

After all of the requests have run, we want to carry out another calculation inside .then(data => { }). If you remember, when a new transaction is created, the mining rewards transaction code, bitcoin.createNewTransaction(12.5, "00" , nodeAddress);, needs to be broadcast throughout the entire blockchain network. At the moment, when a new block is mined, we create a mining reward transaction, but it is not broadcast to the whole network. To broadcast it, the request will be sent to the /transaction/broadcast endpoint, because it already has the functionality to broadcast transactions. We're just going to make a call to this endpoint with the mining reward transaction data passed in.

1. Before passing the mining reward transaction data, however, we need some request options:

Promise.all(requestPromises)
.then(data => {
const requestOptions = {
uri: bitcoin.currentNodeUrl + '/transaction/broadcast',
method: 'POST',
};
})

1. The body data will be sent as an object. In the body, let's add the mining reward transaction data:

Promise.all(requestPromises)
.then(data => {
const requestOptions = {
uri: bitcoin.currentNodeUrl + '/transaction/broadcast',
method: 'POST',
body: {
amount: 12.5,
sender:"00",
recipient: nodeAddress
}
};
})

1. Finally, after the body, set json to true by adding the following line:

json: true

1. Then, after the requestOptions, let's send the following request:

return rp(requestOptions);

At this point, inside the /mine endpoint, a bunch of calculations are being carried out to create a new block. Then, once the new block is created, it is broadcast to all the other nodes inside the network. After the broadcast is complete inside the .then block, a new request to the /transaction/broadcast endpoint is made. This request will create a mining reward transaction and the nodes will then broadcast it to the entire blockchain network. Then, after the request runs and all of the calculations are complete, a response is sent: New block mined successfully .