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https://github.com/mslinn/web3j-scala
Lightweight and idiomatic Scala wrapper around Web3J for Ethereum.
https://github.com/mslinn/web3j-scala
ethereum json-rpc scala solc solidity web3j
Last synced: 10 days ago
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Lightweight and idiomatic Scala wrapper around Web3J for Ethereum.
- Host: GitHub
- URL: https://github.com/mslinn/web3j-scala
- Owner: mslinn
- Created: 2017-11-07T20:03:05.000Z (almost 7 years ago)
- Default Branch: master
- Last Pushed: 2021-12-23T12:08:54.000Z (almost 3 years ago)
- Last Synced: 2023-03-12T09:42:22.631Z (over 1 year ago)
- Topics: ethereum, json-rpc, scala, solc, solidity, web3j
- Language: Scala
- Homepage: https://www.web3j.io
- Size: 3.55 MB
- Stars: 82
- Watchers: 6
- Forks: 22
- Open Issues: 17
-
Metadata Files:
- Readme: README.md
- Funding: .github/FUNDING.yml
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README
# DEATH NOTICE
May 8, 2020: I have abandoned this project and will not update it. If someone else wants to take it over please contact me.
-- Mike
# Web3J-Scala Library
[](https://badge.fury.io/gh/mslinn%2Fweb3j-scala)
`web3j-scala` is an idiomatic Scala wrapper around [Web3J](https://www.web3j.io) for Ethereum.
Web3J is a lightweight, reactive, somewhat type safe Java and Android library for integrating with nodes on Ethereum blockchains.
Web3J features RxJava extensions, and `web3j-scala` wraps that syntax in Scala goodness.
For example, the `web3j-scala` [observable methods](http://mslinn.github.io/web3j-scala/latest/api/com/micronautics/web3j/Web3JScala$.html)
provide [simple and efficient application code](https://github.com/mslinn/web3j-scala/blob/master/demo/DemoObservables.scala#L14-L22).
Scala's [value classes are used](https://github.com/mslinn/web3j-scala/blob/master/src/main/scala/com/micronautics/web3j/ValueClasses.scala)
to provide much stronger type safety than Web3J, without incurring a runtime penalty.
## Use As a Library
Add this to your SBT project's `build.sbt`:
resolvers ++= Seq(
"micronautics/scala on bintray" at "https://dl.bintray.com/micronautics/scala",
"ethereum" at "https://dl.bintray.com/ethereum/maven/"
)
libraryDependencies += "com.micronautics" %% "web3j-scala" % "4.5.17" withSources()
This library is cross-built for Scala 2.12 and 2.13. Tested with Oracle JDK 8 and OpenJDK 8 & 11.
## Questions and Problems
This library merely wraps [Web3J](https://www.web3j.io), so if you have questions about how to use this library,
please [read their docs](https://web3j.readthedocs.io/en/stable/quickstart.html), and participate in [their Gitter channel](https://gitter.im/web3j/web3j).
If you find a bug in this library you can [post an issue here](https://github.com/mslinn/web3j-scala/issues).
## Run the Demo Program
The demo program performs the following:
- Follows the outline of the [Web3J Getting Started](https://docs.web3j.io/getting_started.html#start-sending-requests) documentation,
adapted for Web3J-Scala, including synchronous and asynchronous versions of the available methods.
- Compiles an example Solidity program that defines a smart contract.
- Creates a JVM wrapper from an example smart contract.
To run the demo:
1. Start up an Ethereum client if you don’t already have one running, such as `geth`.
The `bin/runGeth` script invokes `geth` with the following options, which are convenient for development but not secure enough for production:
- The Ethereum data directory is set to `~/.ethereum`, or a subdirectory that depends on the network chosen;
the directory will be created if required.
- HTTP-RPC server at `localhost:8545` is enabled, and all APIs are allowed.
- Ethereum's experimental Whisper message facility is enabled.
- Inter-process communication will be via a virtual file called `geth.ipc`,
located at `~/.ethereum` or a subdirectory.
- WS-RPC server at `localhost:8546` is enabled, and all APIs are allowed.
- Info verbosity is specified.
- A log file for the `geth` output will be written, or overwritten, in `logs/geth.log`;
the `log/` directory will be created if it does not already exist.
```
$ mkdir logs/
$ geth \
#--datadir .ethereum/devnet --dev \ # boots quickly but has no deployed contracts from others
--datadir .ethereum/rinkeby --rinkeby \ # takes about 15 minutes to boot, but has contracts
--ipcpath geth.ipc \
--metrics \
--rpc \
--rpcapi eth,net,web3,clique,debug,eth,miner,personal,rpc,ssh,txpool \
--shh \
--ws \
--wsapi eth,net,web3,clique,debug,eth,miner,personal,rpc,ssh,txpool \
--verbosity 2
```
You will see the message `No etherbase set and no accounts found as default`.
Etherbase is the index into `personal.listAccounts` which determines the account to send Ether too.
You can specify this value with the option `--etherbase 0`.
2. The shell that you just used will continuously scroll output so long as `geth` continues to run,
so type the following into another shell:
```
$ bin/demo
```
The demo has two major components:
1. [Creates a JVM wrapper](https://github.com/mslinn/web3j-scala/blob/master/demo/DemoSmartContracts.scala)
for the [sample smart contract](https://github.com/mslinn/web3j-scala/blob/master/src/test/resources/basic_info_getter.sol).
2. The second portion of the demo consists of the following:
- Examples of using `web3j-scala`'s [synchrounous and asynchronous APIs](https://github.com/mslinn/web3j-scala/blob/master/demo/Demo.scala)
- Examples of working with [RxJava's Observables from Scala](https://github.com/mslinn/web3j-scala/blob/master/demo/DemoObservables.scala)
- Examples of working with [JVM wrappers around Ethereum smart contracts](https://github.com/mslinn/web3j-scala/blob/master/demo/DemoSmartContracts.scala).
- Examples of using [transactions](https://github.com/mslinn/web3j-scala/blob/master/demo/DemoTransaction.scala)
with Ethereum wallet files and the Ethereum client.
3. The `bin/web3j` script runs the [Web3J command-line console](https://docs.web3j.io/command_line.html).
The script builds a fat jar the first time it is run, so the command runs quickly on subsequent invocations.
4. More scripts are provided in the `bin/` directory, including:
- [bin/attachHttp](https://github.com/mslinn/web3j-scala/blob/master/bin/attachHttp) -
Attach to a running geth instance via HTTP and open a
[JavaScript console](https://godoc.org/github.com/robertkrimen/otto)
- [bin/attachIpc](https://github.com/mslinn/web3j-scala/blob/master/bin/attachIpc) -
Attach to a running geth instance via IPC and open a JavaScript console.
This script might need to be edited if a network other than `devnet` is used.
- [bin/getApis](https://github.com/mslinn/web3j-scala/blob/master/bin/gethApis) -
Reports the available APIs exposed by this `geth` instance.
- [bin/isGethListening](https://github.com/mslinn/web3j-scala/blob/master/bin/isGethListening) -
Verifies that `geth` is listening on HTTP port 8545
## Developers
### API Documentation
* [This library's Scaladoc is here](http://mslinn.github.io/web3j-scala/latest/api/com/micronautics/web3j/index.html)
and the [gitter channel is here](https://gitter.im/web3j-scala/Lobby).
* [The Web3J JavaDoc is here](https://jar-download.com/java-documentation-javadoc.php?a=core&g=org.web3j&v=3.0.2),
and here is the [Web3J gitter channel](https://gitter.im/web3j/web3j).
### Publishing
1. Update the version string in `build.sbt` and in this `README.md` before attempting to publish to Bintray.
2. Commit changes with a descriptive comment:
```
$ git add -a && git commit -m "Comment here"
```
3. Publish a new version of this library, including committing changes and updating the Scaladoc with this command:
```
$ sbt publishAndTag
```
### Updating Scaladoc
1. Use the Scaladoc project; first do a [preflight check of the Scaladoc output](https://github.com/mslinn/multi-scaladoc#preflight-check-optimize-your-scaladoc-source):
```
sbt "; project web3j-scala; doc; project demo; doc"
```
2. Now [Update the Git Version String and Make a New Tag](https://github.com/mslinn/multi-scaladoc#update-the-git-version-string-and-make-a-new-tag).
3. Now [edit the multi-scaladoc settings](https://github.com/mslinn/multi-scaladoc#running-this-program)
```
export SCALADOC_SUB_PROJECT_NAMES="web3j-scala,demo"
```
4. Run multi-scaladoc:
```
../scaladoc/bin/run
```
### Updating Scaladoc and Committing Changes Without Publishing a New Version
This task rebuilds the docs, commits the git repository, and publishes the updated Scaladoc without publishing a new version:
$ sbt commitAndDoc
## Sponsor
This project is sponsored by [Micronautics Research Corporation](http://www.micronauticsresearch.com/),
the company that delivers online Scala training via [ScalaCourses.com](http://www.ScalaCourses.com).
You can learn Scala by taking the [Introduction to Scala](http://www.ScalaCourses.com/showCourse/40),
and [Intermediate Scala](http://www.ScalaCourses.com/showCourse/45) courses.
Please [contact us](mailto:[email protected]) to discuss your organization’s training needs.
## License
This software is published under the [Apache 2.0 License](http://www.apache.org/licenses/LICENSE-2.0.html).