Network considerations

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En provenance du cours de IBM

IBM Blockchain Foundation for Developers

1296 notes

IBM

IBM Blockchain Foundation for Developers

1296 notes

If you're a software developer and new to blockchain, this is the course for you. Several experienced IBM blockchain developer advocates will lead you through a series of videos that describe high-level concepts, components, and strategies on building blockchain business networks. You'll also get hands-on experience modeling and building blockchain networks as well as create your first blockchain application. The first part of this course covers basic concepts of blockchain, and no programming skills are required. However, to complete three of the four labs, you must understand basic software object-oriented programming and how to use the command line. It's also helpful, but not required, that you can write code in JavaScript. When you complete the course, you should understand what a blockchain business network is, how to build and model a simple blockchain solution, and the role of the developer in creating blockchain applications. If you choose to take this course and earn the Coursera course certificate, you will also earn an IBM digital badge upon successful completion of the course. You'll need to pass several end-of-section quizzes and a final exam that include multiple choice, true and false, and fill in the blank questions. This course does not cover Bitcoin or cryptocurrency in detail.

À partir de la leçon

Blockchain fabric development and architecture

In this module, you'll learn more about the components of a blockchain solution and about the roles of people who model, build, and maintain that blockchain solution. You'll also learn to use command-line tools to build a simple application in JavaScript that queries and updates a prepopulated blockchain network ledger. You'll also learn more about the architecture of a blockchain network and about key considerations for developers, administrators, and network consensus. You'll also get hands-on experience working with a sample Hyperledger Fabric network that includes two organizations, two peer nodes, and an ordering service.

Network considerations5:04

Rencontrer les enseignants

Ant Cole
WW Blockchain Enablement
IBM Blockchain
Dave Gorman
Global Blockchain Labs Engagement
IBM Industry Platform

Network considerations.

So what we see here is this is the type of peers the we're

looking through and the methodology that we reach a consensus.

So we've got two different types of system.

First, we've got the peer.

And this may look like two different peers but they are really

the same peer but you decide do I just want

a committing pair that's just submitting in transactions,

or do I want that peer to be an endorsing peer?

So it can validate did you follow the rules.

Did you follow the smart contract.

So this is what the peers have,

and then we have the ordering service.

So we'll have a set of ordering nodes that will probably be clustered

in one location that will then be able to run these transactions,

and verify which ones should be in each batch.

They do nothing really more than that.

They can't read or use the transactions from that point of view.

So, let's step through how we submit a transaction,

and how this will then become a block on the chain.

So we start off with an application,

is going to submit in a transaction.

We then have each node will have an endorsement policy.

And what an endorsement policy does is it starts

defining who can do what and who is able to endorse a specific transaction.

So for example, if I'm trying to change the color of a car,

the endorsement policy will say for this smart contract that I'm using,

that I have to use

three different endorsers to say that this transaction was a good transaction.

And this can vary by which smart contract you are using,

but it'll also say that we've got different peers on the network

here that are not part of that endorsement policy.

So, we've sent it to all those endorsers,

who are within policy,

and then each of these endorsers then execute that transaction.

So by execution I mean,

they're running the transaction against the smart contract,

checking things like that I as a user I'm allowed to do this transaction,

that this transaction follows the rules in the smart contract.

It will then verify that that was a good transaction

by sending back the original transaction along with a signature.

And that signature will say that that was a good transaction,

and it also gives the read in the right set to say

this is what I've read from the database and this is what I'm writing to it.

So what this client can do is check for those read write sets are matching.

So they get say deterministic result.

It can throw it out optionally at that stage if it wants to,

but if it doesn't, it will be thrown out later stage.

It just goes through more processing to get to that throw stage.

So, once that transaction has been verified by each of the endorses,

then the transaction is submitted to the ordering service.

And this ordering service is receiving many other transactions from

many other applications doing the same process as we're going through.

So group these up into a bunch of transactions within each block,

and what it then does is distribute out to

all those peers what is going to be in the next block.

Once it's distributed out,

each peer can then send it on to the other peer in the network,

but mostly it's sent out to all the peers in the network,

and then each one of these then verifies that those transactions were correct.

And in doing so, they'll validate that

the next block should be added into the chain, and then,

they will then send out to the world that this block has been added,

and the original application will receive a notification

to say your transaction has been added into the block.

So we see here, we've got the seven step process on how

we go through the consensus methodology,

and where we saw before that we've got different methodologies

of so low or Kafka Zookeeper,

that's what's taking place within this ordering service here,

and that's how it orders the transactions that are coming through.

So, what we'll then see on this side of things is that

the consensus consideration is really built

around the same way that you build a business network that we see today.

So, what we have is you might have different endorsers within each business,

and each business will then define do I want to be an endorser, or do I not?

So, a manufacturer for a car,

and a dealership for a car may be endorsing for a color change,

but someone who isn't part of

this different manufacturer may not have to endorse such a transaction.

So that's the process that we go through on that side.

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