This document summarizes a presentation on developing blockchain applications using Hyperledger Fabric. It discusses key Hyperledger Fabric concepts like chaincode, which defines the business logic of a blockchain application. Chaincode is written in languages like Go and JavaScript. It also discusses the Hyperledger Fabric architecture, including components like peers, orderers, and how channels isolate ledgers in the network. The presentation provides examples of querying and updating state databases using chaincode. It demonstrates typical workflows for deploying chaincode to networks like Oracle Autonomous Blockchain Cloud Service.

1.  überraschend mehr Möglichkeiten!
DOAG 2018 Konferenz, 22.11.2018
Andreas Chatziantoniou, Matthias Fuchs, Borys Neselovskyi
Eine Reise durch die Blockchain
Applikationsentwicklung

2. Eine Reise durch die Blockchain Applikationsentwicklung
Über uns…
Andreas Chatziantoniou
@MagicChatzi
DevTops, Nürnberg
OCA 10
AS, EM Certified
Middleware
Matthias Fuchs
@hias222
DevTops, Nürnberg
OCP 12
Exadata, RAC, Java Cloud
Certified
Database, Middleware
Borys Neselovskyi
@bneselov
OPITZ CONSULTING, Essen
OCP 8, 10, 12
Database, Middleware,
Engineered Systems
Cloud Technology
BMA

3. Seite 3
Agenda
1
2
3
4
Hyperledger Basics
Chaincode
All about Networking
Eine Reise durch die Blockchain Applikationsentwicklung
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4. Seite 4
Hyperledger Basics
1
Eine Reise durch die Blockchain Applikationsentwicklung

5. Eine Reise durch die Blockchain Applikationsentwicklung
The current world
Shop Bank
Insurance Regulator Manufacturer
Customer
A

6. The current world – with Hyperledger Fabric
Shop Bank
Insurance Regulator
Customer
Blockchain Ledger
shared, replicated, permissioned
A
Eine Reise durch die Blockchain Applikationsentwicklung
Manufacturer

7. What the business wants
 Privacy
 All transactions have security embedded
 Authentication and access controls are
enabled for granular access
 Shared Ledger
 Database is immutable (append only)
 Shared across the business network
 Trust
 All the transactions are verified and
endorsed by the trusted relevant parties
 Smart contract
 Business logic is embedded within the
database and executed to validate and
store the transactions
A
Eine Reise durch die Blockchain Applikationsentwicklung

8. Properties of a Distributed Ledger
 Decentralized, replicated across many participants, each of whom
collaborate in its maintenance
 Information recorded is append-only
 Immutability makes it simple to determine the provenance of the
information
 These properties makes it called as “Systems of Proof”
A
Eine Reise durch die Blockchain Applikationsentwicklung

9. HyperLedger Fabric Key Features
 Private and permission based
 Members of HyperLedger Fabric enrolls thru MSP - Membership Service
Provider
 Different MSPs are supported
 Ledger data can be stored in multiple formats.
 Consensus mechanisms can be switched in and out
 Ability to create channels - Allowing a group of participants to create a
separate ledger of transactions.
A
Eine Reise durch die Blockchain Applikationsentwicklung

10. Hyperledger Fabric Deployment Model
Src: Metamagic Global
A
Eine Reise durch die Blockchain Applikationsentwicklung

11. Hyperledger Fabric – Assets/Smart Contract
 Assets
 Real world physical/financial assets
 Represented as a collection of key-value
pairs
 state changes recorded as transactions on
a Channel ledger
 Assets can be represented in binary
and/or JSON form
 Smart Contracts
 Defining an asset and the transaction
instructions for modifying it
 Enforces rules for reading or altering key
value pairs
 Executes against the ledger’s current state
database & are initiated through a
transaction proposaI
 Execution results in a set of key value
writes (write set) that can be submitted to
the network and applied to the ledger on
all peers
A
Eine Reise durch die Blockchain Applikationsentwicklung

12. Hyperledger Fabric – Ledger/Channels
 Ledger
 Ledger is the sequenced, tamper-resistant
record of all state transitions in the fabric
 State transitions are a result of Chaincode
invocations (‘transactions’) submitted by
participating parties
 Each transaction results in a set of asset
key-value pairs that are committed to the
ledger as creates, updates, or deletes
 The ledger is comprised of a Blockchain
(‘chain’) to store the immutable,
sequenced record in blocks
 Channels
 There is one ledger per channel
 Each peer maintains a copy of the ledger
for each channel of which they are a
member
 Private “subnet” of communication
between two or more specific network
members, for the purpose of conducting
private and confidential transactions
 Channel is a completely separate instance
of HyperLedger Fabric. Every Channel is
completely isolated and will never talk to
each other
A
Eine Reise durch die Blockchain Applikationsentwicklung

13. Hyperledger vs Bitcoin A
Eine Reise durch die Blockchain Applikationsentwicklung
Hyperledger Fabric Bitcoin
Provides Identity Anonymity
Practical Byzantine Fault Tolerance Proof of work
Assets Cryptocurrency
Selective Endorsement Zero Trust

14. Seite 14
Chaincode
2
Eine Reise durch die Blockchain Applikationsentwicklung

15. Eine Reise durch die Blockchain Applikationsentwicklung
What is Chaincode?
 Chaincode is software defining the business logic
 Chaincode is a piece of code that is written in Javascript / Go / Node.js
 Chaincode enforces the rules for reading or altering key-value pairs or
other state database information.
 Chaincode functions execute against the ledger’s current state database
and are initiated through a transaction proposal.
 Chaincode execution results in a set of key-value writes (write set) that can
be submitted to the network and applied to the ledger on all peers.
Source: https://hyperledger-fabric.readthedocs.io/en/release-1.3/fabric_model.html
B

16. Eine Reise durch die Blockchain Applikationsentwicklung
Chaincode: two perspectives
 Chaincode for Developers
 Developing a blockchain
application
 Chaincode for Operator
 Managing blockchain network
 Maintenance chaincode by:
 Install
 Instantiate
 upgrade
B

17. Eine Reise durch die Blockchain Applikationsentwicklung
Chaincode Interface
 Methods:
B

18. Eine Reise durch die Blockchain Applikationsentwicklung
Chaincode Interface
 Dependencies:
 Package shim provides APIs for the chaincode
to access its state variables, transaction context
and call other chaincodes:
 Can be generated:
import
"github.com/hyperledger/fabric/core/chain
code/shim"
 Functions:
 * fmt: contains PrintIn for debugging/logging
 * error: standard go error format
B
Source: https://fabrictestdocs.readthedocs.io/en/latest/chaincode.html

19. Eine Reise durch die Blockchain Applikationsentwicklung
Package shim: Logging Control
 Create a logging object for use by a chaincode:
NewLogger(name string) *ChaincodeLogger
 Set the logging level of the logger:
(c *ChaincodeLogger) SetLevel(level LoggingLevel)
 Return true if logs will be generated at the given level:
(c *ChaincodeLogger) IsEnabledFor(level LoggingLevel) bool
 A LoggingLevel is a member of the enumeration:
LogDebug, LogInfo, LogNotice, LogWarning, LogError, LogCritical
 which can be used directly, or generated by passing a case-insensitive version of the strings:
DEBUG, INFO, NOTICE, WARNING, ERROR, CRITICAL
B
Source: https://hyperledger-fabric.readthedocs.io/en/release-1.2/logging-control.html

20. Eine Reise durch die Blockchain Applikationsentwicklung
Package shim: Type Response
 A response with a representation similar to an HTTP response that can be used within another
message

B

21. Eine Reise durch die Blockchain Applikationsentwicklung
Package shim: Type ServerStatus_StatusCode
 type ServerStatus_StatusCode int32
B

22. Eine Reise durch die Blockchain Applikationsentwicklung
Oracle Autonomous Blockchain Cloud Service (OABCS)
 Chaincode is written in Go or node.js and packaged into a ZIP file
 Create the package.json file with two sections:
 The scripts section declares how to launch the chaincode
 The dependencies section specifies the dependencies
Source: https://docs.oracle.com/en/cloud/paas/blockchain-cloud/user/write-chaincode.html#GUID-64153568-41D2-40E6-9F66-EF384AFEC8E9
B

23. Eine Reise durch die Blockchain Applikationsentwicklung
Oracle Autonomous Blockchain Cloud Service (OABCS)
Source: https://docs.oracle.com/en/cloud/paas/blockchain-cloud/user/typical-workflow-deploy-chaincodes.html
B

24. Eine Reise durch die Blockchain Applikationsentwicklung
REST API for Oracle Autonomous Blockchain Cloud Service
 Administer Chaincode:
 Get Chaincode Information:
 Method: GET
 Path: /console/admin/api/v1.1/chaincodes/{chaincodeName}
 Install a Chaincode:
 Method: POST
 Path: /console/admin/api/v1.1/chaincodes
 Instantiate a Chaincode:
 Method: POST
 Path: /console/admin/api/v1.1/chaincodes/{chaincodeName}/instantiate
 List of all REST Endpoints:
 https://docs.oracle.com/en/cloud/paas/blockchain-cloud/rest-api/rest-endpoints.html
B

25. Blockchain Overview25
3

26. Integration Blockchain
Call
Events
State
Eine Reise durch die Blockchain Applikationsentwicklung
M

27. Access (hyperledger)
 Query State DB (CouchDB)
 versioned key-value store (KVS)
 blobs
 Fabric Core
 Rest
 Cli
 Hyperledger Fabric SDKs Document Store
schema-free
RESTful HTTP/JSON API
M

28. Eine Reise durch die Blockchain Applikationsentwicklung
Access Path (hyperledger)
Rest
EndpointsRest
Endpoints
Micro-
services
Micro-
services
Micro-
services
Rest Connects
IoT Devices
Integration
CLI (peer cmds)
Rest
SDK (java, node
..)
M

29. Events
 event hub
 This service sent events any time a new
block was added to the peer’s ledger,
regardless of the channel to which that
block pertained
New since 1.1
 Event services
 Deliver
 DeliverFiltered
SDK with
Integratio
n
SDK (java, node
..)
M

30. Peers and Microservices (hyperledger)
Hyperledger
Fabric
Endorser,
Commiter
chaincode
Orderer
Rest
EndpointsRest
Endpoints
Micro-
services
Micro-
services
Micro-
services
Org 1 Org 2
Orderer
Rest
EndpointsRest
Endpoints
Micro-
services
Micro-
services
Micro-
services
Hyperledger
Fabric
Endorser,
Commiter
chaincode
M

31. Peers and Microservices
Org 1
Orderer
Rest
EndpointsRest
Endpoints
Micro-
services
Micro-
services
Micro-
services
Hyperledger
Fabric
Endorser,
Commiter
chaincode
Container
Services
Contionous
Integration
Plan
Code
Build
Test M

32. Eine Reise durch die Blockchain Applikationsentwicklung
Demo

33. Development 1 – Basic Tasks
 Query
 Most queries against the state
DB
 Chaincode shim interface
 Updates
 channel.SendTransactionPropos
al
 The ordering service bundles
the transaction into a block and
delivers it to all peers on a
channel for validation

34. Development – 2 Example Swagger
 Using hyperledger
composer
 Yeoman generates a
template
 Some examples from
fabric
 Start rest server

35. OpenAPI Swagger.json

36. Development 3 - Clients
Nswag
 https://github.com/RSuter/
NSwag
Swagger
https://editor.s
wagger.io/
https://editor.swagger.io/

37. Import to Angular

38. Cloud

39. Oracle Rest Proxy

40. Seite 40Eine Reise durch die Blockchain Applikationsentwicklung
Fragen