1. Hyperledger Fabric 소개 및 튜토리얼
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2. Contents Key Concept How Hyperledger Fabric Service Works?
What is happening underneath the Service?
Tutorials

4. 1
KEY CONCEPT

5. Permissioned vs Permissionless

6. Execute-Order-Validate
Hyperledger Fabric architecture for transactions:
- in contrast with order-execute model
Separate transaction flow into 3 steps
Execute: execute transaction, validate then endorsing it
Order: order transaction
Validate: validate transactions with endorsement policy,
then commit to ledger

7. A : Which peer nodes, How many of peers need to endorse
Execute-Order-Validate
Q : Endorsement Policy??
Hyperledger Fabric architecture for transactions:
- in contrast with order-execute model
Separate transaction flow into 3 steps
Execute: execute transaction, validate then endorsing it
Order: order transaction
Validate: validate transactions with endorsement policy,
then commit to ledger
A : Which peer nodes, How many of peers need to endorse
for given smart contract.

8. How Hyperledger Fabric Service Works?2
How Hyperledger Fabric Service Works?

9. 2. How Hyperledger Fabric Service Works?
Scenario
Client A wants to buy food from Client B

10. 2. How Hyperledger Fabric Service Works?
Assumption
Client A = The application user
‘Peers’ installed ‘chaincode’
‘Channel’ instantiate chaincode
Chaincode defines transaction instructions and food price

11. 2. How Hyperledger Fabric Service Works?
Assumption
Q : Application User?
Client who invoke or query chaincode
User should be registered & enrolled with Organization’s CA
Client A = The application user
‘Peers’ installed ‘chaincode’
‘Channel’ instantiate chaincode
Chaincode defines transaction instructions and food price

12. 2. How Hyperledger Fabric Service Works?
Assumption
Q : Channel?
Channel allows a group of participants to create a separate ledger
Provide a mechanism for private communications and private data
Client A = The application user
‘Peers’ installed ‘chaincode’
‘Channel’ instantiate chaincode
Chaincode defines transaction instructions and food price

13. 2. How Hyperledger Fabric Service Works?
Client A initiates a transaction
Client A send a request to purchase food
SDK creates transaction proposal
transaction proposal is a request to invoke a chaincode
User credential produce a unique signature for this proposal

14. 2. How Hyperledger Fabric Service Works?
Endorsing peers verify & execute transaction
Endorsing peers verify transaction proposal
Endorsing peers execute the transaction, but NOT UPDATE ledger
Sent back proposal response(endorsing peer’s signature + delta set)

15. 2. How Hyperledger Fabric Service Works?
Q : Endorsing Peer?, Peer?
Endorsing peers verify & execute transaction
Peer which install chaincode can be endorsing peer
Endorsing peer create signed transaction response using its own chaincode
All the peer in the channel is committing peer
Committing peer receive blocks, validate then commit to ledger
Endorsing peers verify transaction proposal
Endorsing peers execute the transaction, but NOT UPDATE ledger
Sent back proposal response(endorsing peer’s signature + delta set)

16. 2. How Hyperledger Fabric Service Works?
Proposal responses are inspected
Client B application verifies endorsing peer signatures and compares the proposal responses

17. 2. How Hyperledger Fabric Service Works?
Client sends transaction to Ordering Service
The application broadcast transaction proposal and response to Ordering Service
Ordering Service receives transactions from all channels in the network
Order transactions by channel, creates blocks per channel

18. 2. How Hyperledger Fabric Service Works?
Transaction is validated
Blocks are delivered to all peers on the channel
Validate that there are no changes for delta set
Transactions in the block are tagged as valid or invalid

19. 2. How Hyperledger Fabric Service Works?
Ledger updated
Each peer appends block to the channel’s chain
For valid transactions the delta sets are committed to db

20. What is happening underneath the Service?3
What is happening underneath the Service?

21. Create the Network 3. What will happen underneath the Service?
The network is formed when an orderer is started
Orderer O4 is initially configured and started by administrator in org R4
Network configuration NC4 contains policies admin capabilities for the network
N: network
O4: ordering service
NC4: network configuration
R4: organization
CA4: R4 CA

22. Q : CA(Certificate Authorities)?
3. What will happen underneath the Service?
Q : CA(Certificate Authorities)?
Create the Network
CA is used to issue certificates to administrators and network nodes
Certificates uses to identify components belonging to R4
So different organizations usually use different CA
Certificates also used to endorse & validate transaction.
The network is formed when an orderer is started
Orderer O4 is initially configured and started by administrator in org R4
Network configuration NC4 contains policies admin capabilities for the network
N: network
O4: ordering service
NC4: network configuration
R4: organization
CA4: R4 CA

23. Add Network Administrator
3. What will happen underneath the Service?
Add Network Administrator
Organization R1 is added to network as administrator, now R1 and R4 have equal rights
We can see CA1 has been added, which is used to identify users from R1 organization
Because both R1, R4 have admin rights, can update network configuration, to allow other organization to operate on network
At this point ordering Service is a single node, but usually they are multi-mode
N: network
O4: ordering service
NC4: network configuration
R4: organization
CA4: R4 CA
R1: organization
CA1: R1 CA

24. Defining a Consortium 3. What will happen underneath the Service?
Consortium defines the set of organizations in the network who share a need to communicate each other
Because R1, R4 have administrative rights, only R1 and R4 can make new consortium
The “consortium” world literally means “a group with a shared destiny”
It really makes sense to group organizations together if they have a common goal.
N: network
O4: ordering service
NC4: network configuration
R4: organization
CA4: R4 CA
R1: organization
CA1 R1 CA
R2: organization
CA2: R2 CA
X1: R1, R2 consortium

25. Creating a channel for a consortium
3. What will happen underneath the Service?
Creating a channel for a consortium
The concept of channel can be thought of key part of Fabric blockchain network
A channel is a primary communication mechanism which the members of a consortium can communicate with each other
Channel C1 provides a private communication mechanism for the consortium X1
It is helpful to mention that R4 also allowed R1 to create channels
C1 has a completely separate configurations CC1
CC1 contains the policies that R1, R2 have rights over channel C1
Organizations other than R1, R2 cannot interact with C1
Other organization cannot add itself to the channel C1, it must be authorized by R1 or R2
Channel is useful because they provide a mechanism for private communications between the members of consortium.
It is in a very sense “free from the network”
Organizations that are explicitly specified in a channel configuration have control over channel.
The data in a channel is completely isolated from the rest of the network, including other channels.
R1: organization
CA1 R1 CA
R2: organization
CA2: R2 CA
X1: R1, R2 consortium
C1: channel
CC1: channel configuration
N: network
O4: ordering service
NC4: network configuration
R4: organization
CA4: R4 CA

26. Peers and Ledgers 3. What will happen underneath the Service?
Peer nodes are network components where copies of the blockchain ledger are hosted
First CA1 should issue certficates for P1 identity, which associates P1 with organization R1.
Once P1 is started, it can join channel C1 using the orderer O4.
When orderer O4 receives join request, it uses channel configuration CC1 to determine P1’s permissions on this channel. For example, CC1 determines whether P1 can read or write information to the ledger L1
R1: organization
CA1 R1 CA
R2: organization
CA2: R2 CA
X1: R1, R2 consortium
C1: channel
CC1: channel configuration
P1: peer node
L1: copy of the ledger
N: network
O4: ordering service
NC4: network configuration
R4: organization
CA4: R4 CA

27. Applications and Smart Contract chaincode
3. What will happen underneath the Service?
Applications and Smart Contract chaincode
We can start connecting client applications to consume some of the services provided by the ledger
In diagram, we can see that client application A1 can use channel C1 to connect to specific network resources
Through connected C1, A1 now can connect to both peer node P1 and orderer node O4
Just like peers, a client application will have an identity that associates it with an organization. In this example, client application A1 is associated with organization R1
A1 is outside the Fabric network, it is connected to it via the channel C1
It might now apper that A1 can access the ledger L1 directly via P1, but all access is managed via a smart contract chaincode, S5
Think of S5 as all the common access patterns to the ledger
S5 provides set of ways by which the ledger L1 can be queried or updated.
In short, client application A1 has to go through smart contract S5 to get to ledger L1
Chaincodes developed in each organization to implement a business logic shared by the consortium members. Chaincodes are used to help generate transactions which can be subsequently distributed to the every node
C1: channel
CC1: channel configuration
P1: peer node
L1: copy of the ledger
S5: smart contract
A1: Client application
N: network
O4: ordering service
NC4: network configuration
R4: organization
CA4: R4 CA
R1: organization
CA1 R1 CA
R2: organization
CA2: R2 CA
X1: R1, R2 consortium

28. Installing a smart contract
3. What will happen underneath the Service?
Applications and Smart Contract chaincode
install
Installing a smart contract
After S5 developed, administrator in organization R1 must install onto peer node P1
After installation P1 has full knowledge of S5
Specifically, P1 can see the implementation logic of S5
When organization has multiple peers in a channel, it can choose the peers which it installs smart contracts
It does not need to install a smart contract on every peer.
Instantiating a smart contract
However the other components connected to channel C1 are unaware of it, it must first be instantiated on channel C1
C1: channel
CC1: channel configuration
P1: peer node
L1: copy of the ledger
S5: smart contract
A1: Client application
N: network
O4: ordering service
NC4: network configuration
R4: organization
CA4: R4 CA
R1: organization
CA1 R1 CA
R2: organization
CA2: R2 CA
X1: R1, R2 consortium

29. Instantiating a smart contract
3. What will happen underneath the Service?
Applications and Smart Contract chaincode
install
instantiate
Instantiating a smart contract
However the other components connected to channel C1 are unaware of it, it must first be instantiated on channel C1
In this example, administrator in organization R1 must instantiate S5 on channel C1 using P1.
After instantiation, every component on channel C1 is aware of the existence of S5
And in our example, it means that S5 can now be invoked by client application A1
* Note that although every component on the channel can now access S5, they are not able to see its program logic
R1: organization
CA1 R1 CA
R2: organization
CA2: R2 CA
X1: R1, R2 consortium
C1: channel
CC1: channel configuration
P1: peer node
L1: copy of the ledger
S5: smart contract
A1: Client application
N: network
O4: ordering service
NC4: network configuration
R4: organization
CA4: R4 CA

30. Applications and Smart Contract chaincode
3. What will happen underneath the Service?
Applications and Smart Contract chaincode
install
Endorsement Policy
instantiate
Endorsement Policy
Important piece of additional information supplied at instantiation is an endorsement policy
It describes which organizations must approve transactions before they are accepted
The act of instantiation places the endorsement policy in channel configuration
Invoking a smart contract
Once a smart contract has been installed on a peer node and instantiated on a channel, it can be invoked by a client application
Client applications do this by sending transaction proposals to peers owned by the organizations specified by the smart contract endorsement policy.
C1: channel
CC1: channel configuration
P1: peer node
L1: copy of the ledger
S5: smart contract
A1: Client application
N: network
O4: ordering service
NC4: network configuration
R4: organization
CA4: R4 CA
R1: organization
CA1 R1 CA
R2: organization
CA2: R2 CA
X1: R1, R2 consortium

31. Complete R2 network infrastructure
3. What will happen underneath the Service?
Complete R2 network infrastructure
Organization R2 has added a peer node, P2, on channel C1
P2 also hosts a copy of the ledger L1 and smart contract S5
R2 has also added client application A2 which can connect to network via channel C1
Administrator in org R2 has created P2 and joined it to channel C1, in the same way as an administrator in R1
At this stage in network development, we have a channel in which org R1, R2 can fully communicate with each other
Specifically, this means that A1, A2 can generate transactions using smart contract S5 and L1 on channel C1
C1: channel
CC1: channel configuration
P1: peer node
L1: copy of the ledger
S5: smart contract
A1: Client application
A2: Client application
P2: peer node
N: network
O4: ordering service
NC4: network configuration
R4: organization
CA4: R4 CA
R1: organization
CA1 R1 CA
R2: organization
CA2: R2 CA
X1: R1, R2 consortium

32. Complete R2 network infrastructure
3. What will happen underneath the Service?
Complete R2 network infrastructure
install
Install not instantiate
Organization R2 must install smart contract S5 onto its peer node P2. That’s obvious, if applications A1 or A2 wish to use S5 on peer node P2 to generate transactions, it must first be present
Installation is the mechanism by which this happens
However, in contrast to org R1, org R2 does not need to instantiate smart contract S5 on channel C1. That’s because S5 has already been instantiated on the channel by R1.
Instantiation only needs to happen once, any peer which subsequently joins the channel knows that smart contract S5 is available to the channel
C1 connects two client applications
Since there is only one channel, there is only one logical ledger
C1: channel
CC1: channel configuration
P1: peer node
L1: copy of the ledger
S5: smart contract
A1: Client application
A2: Client application
P2: peer node
N: network
O4: ordering service
NC4: network configuration
R4: organization
CA4: R4 CA
R1: organization
CA1 R1 CA
R2: organization
CA2: R2 CA
X1: R1, R2 consortium

33. 4
Tutorials

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9월 오픈랩 세미나
It-chain committer 김주형