webuj-scala is an idiomatic Scala wrapper around WebuJ for HappyUC. WebuJ is a lightweight, reactive, somewhat type safe Java and Android library for integrating with nodes on HappyUC blockchains.

WebuJ features RxJava extensions, and webuj-scala wraps that syntax in Scala goodness. For example, the webuj-scala observable methods provide simple and efficient application code. Scala's value classes are used to provide much stronger type safety than WebuJ, without incurring a runtime penalty.

Add this to your SBT project's build.sbt:

resolvers += "micronautics/scala on bintray" at "http://dl.bintray.com/micronautics/scala"

libraryDependencies += "com.micronautics" %% "webuj-scala" % "0.2.2" withSources()

Only Scala 2.12 with JDK 8 is supported at present; this is a limitation of the Scala ecosystem as of November 7, 2017.

The demo program performs the following:

• Follows the outline of the WebuJ Getting Started documentation, adapted for WebuJ-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 HappyUC client if you don’t already have one running, such as ghuc. The bin/runGhuc script invokes ghuc with the following options, which are convenient for development but not secure enough for production:
   • The HappyUC data directory is set to ~/.happyuc, 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.
   • HappyUC's experimental Whisper message facility is enabled.
   • Inter-process communication will be via a virtual file called ghuc.ipc, located at ~/.happyuc 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 ghuc output will be written, or overwritten, in logs/ghuc.log; the log/ directory will be created if it does not already exist.

   $ mkdir logs/
   $ ghuc \
      #--datadir .happyuc/devnet --dev \      # boots quickly but has no deployed contracts from others
      --datadir .happyuc/rinkeby --rinkeby \  # takes about 15 minutes to boot, but has contracts
      --ipcpath ghuc.ipc \
      --metrics \
      --rpc \
      --rpcapi huc,net,webuj,clique,debug,huc,miner,personal,rpc,ssh,txpool \
      --shh \
      --ws \
      --wsapi huc,net,webuj,clique,debug,huc,miner,personal,rpc,ssh,txpool \
      --verbosity 2
   

   You will see the message No coinbase set and no accounts found as default. Coinbase is the index into personal.listAccounts which determines the account to send Huc too. You can specify this value with the option --coinbase 0.
2. The shell that you just used will continuously scroll output so long as ghuc continues to run, so type the following into another shell:

   $ bin/demo
   

   The demo has two major components:
   1. Creates a JVM wrapper for the sample smart contract.
   2. The second portion of the demo consists of the following:
      • Examples of using webuj-scala's synchrounous and asynchronous APIs
      • Examples of working with RxJava's Observables from Scala
      • Examples of working with JVM wrappers around HappyUC smart contracts.
      • Examples of using transactions with HappyUC wallet files and the HappyUC client.
3. The bin/webuj script runs the WebuJ command-line console. 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 - Attach to a running ghuc instance via HTTP and open a JavaScript console
   • bin/attachIpc - Attach to a running ghuc 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 - Reports the available APIs exposed by this ghuc instance.
   • bin/isGhucListening - Verifies that ghuc is listening on HTTP port 8545

• This library's Scaladoc is here and the gitter channel is here.

• The WebuJ JavaDoc is here, and here is the WebuJ gitter channel.

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
   

If you just want to republish the Scaladoc for this project, without creating a new version, use this command:

$ sbt scaladoc

This task rebuilds the docs, commits the git repository, and publishes the updated Scaladoc without publishing a new version:

$ sbt commitAndDoc

This project is sponsored by Micronautics Research Corporation, the company that delivers online Scala training via ScalaCourses.com. You can learn Scala by taking the Introduction to Scala, and Intermediate Scala courses.

Micronautics Research also offers HappyUC and Scala consulting. Please contact us to discuss your organization’s needs.

This software is published under the Apache 2.0 License.