Web3j 2.0 introduces options for transaction managers when interacting with Ethereum blockchains, including offline signing, online signing, and support for clients like Quorum. It also improves event filtering by making it simpler to create reactive Observable streams of contract events in Java. The new release integrates with Spring Boot and includes performance improvements like faster light wallet generation and IPC client connections.

1. web3j 2.0
An update
@conors10

2. Transaction Managers
Choose how you transact with Ethereum
blockchains
• Offline signing (web3j)
• Online signing (Ethereum client)
• What about other clients, e.g. Quorum?

3. Transaction Managers
Optional EIP-155
(Replay attack) support
Use a full client
Use Quorum
Use web3j (default)

4. Event filters
Working with filters shouldn’t be hard
Geth/Parity:
1. Create filter
2. Poll for changes
3. Terminate filter
web3j:
• Simple (one line of code)
• Reactive (ReactiveX Observables)

5. Reactive, typed events
Create an
Observable stream
Solidity
Java

6. Homebrew + build info
$ brew tap web3j/web3j
$ brew install web3j
$ web3j version
_ _____ _ _
| | |____ (_) (_)
__ _____| |__ / /_ _ ___
/ / / _ '_ | | | / _
V V / __/ |_) |.___/ / | _ | || (_) |
_/_/ ___|_.__/ ____/| |(_)|_| ___/
_/ |
|__/
Version: 2.0.1
Build timestamp: 2017-02-21 06:19:33.654 UTC

7. web3j + Spring
Spring Boot integration
• web3j-spring-boot-starter

8. Other stuff
Light wallet generation
• ~50msec light
• ~700 msec full
Fast IPC client connections
• Named pipe (Windows)
• Domain socket (OS X/Linux)
Default types
• Empty types for smart contract params - e.g.
Uint256.DEFAULT

9. https://web3j.io