cbaWorkflow : Scala 2.13.4 installation

• installation of scala
• Installation of sbt
• Create a project with sbt

installation of scala

1. log in as root
2. download scala :  wget http://downloads.lightbend.com/scala/2.13.4/scala-2.13.4.rpm
3. yum install scala-2.13.4.rpm
4. verify the files of the installed package and their path: rpm -ql scala-2.13.4
5. verify scala version: scala -version
   Scala code runner version 2.13.4 -- Copyright 2002-2020, LAMP/EPFL and Lightbend, Inc.
6. if scala was upgraded the link in /usr/bin may be missing, the actual install is happening at /usr/share/scala, so either create a link to it, or include /usr/share/scala/bin in your path
7. Log in as a developer user and create a test program: vi first.scala
   

   object first
   {
            def main(args: Array[String]):Unit=
            {
                             println("Hello world")
            }
   }

8. compile the code: scalac first.scala
9. update CLASSPATH:  export CLASSPATH=.:${CLASSPATH}
10. run the code:  scala first
    Hello world
11. Verify scala runner is working properly: scala
    Welcome to Scala 2.13.4 (OpenJDK 64-Bit Server VM, Java 1.8.0_282).
    Type in expressions for evaluation. Or try :help.
    scala> var variables: scala.collection.immutable.Map[String,String] = Map()
    scala> variables += ("path"→"/home/user")
    scala> variables += ("lib"->"my library")
    scala> val b=variables.contains("path")
    scala> val b: Boolean = true
    scala> if(b==true) print(variables("path"))
    /home/user
    scala>:q

Installation is successful if it is the steps have been successful.

Installation of sbt

1. log in as root
2. remove old bintray repo file:
   rm -f /etc/yum.repos.d/bintray-rpm.repo
3. Download the latest repo file :
   cd /etc/yum.repos.d
   curl -L https://www.scala-sbt.org/sbt-rpm.repo
4. install the package:
   yum install sbt
5. verify it works:
   sbt version

Create a project with sbt

1. log in as a developer
2.  create directory structure:
   cd projects/scala
   mkdir sbttest
   cd sbttest
   mkdir -p mkdir -p src/main/scala/com/cba/testsbt
3. create a scala file as follows:
   vi src/main/scala/com/cba/testsbt/first.scala
   

   package com.cba.testsbt

   object first
   {
            def main(args:Array[String]):Unit=
            {
                      println("Hello world of sbt adventures")

             }

   }

4. Compile it:
   sbt compile

5. Run it:
   sbt run

6. check the jar: 
   ls target/scala-2.12/

7. Update the build settings:
   vi build.sbt
   

   val derby = "org.apache.derby" % "derby" % "10.4.1.3"

   ThisBuild / organization := "com.cba"
   ThisBuild / scalaVersion := "2.12.14"
   ThisBuild / version := "1.0"

   lazy val root = (project in file("."))
   .settings(
   name := "First",
   libraryDependencies += derby
   )

8. Build a jar. Note the dependencies are being resolved and artifacts are being fetched from maven repository:
   sbt package
9. Execute the package, note the jar is having a different name now:
   sbt run
10. copy the jar to the home directory and execute it outside of sbt:
    [dataexplorer1@r01edge sbttest]$ cp target/scala-2.12/first_2.12-1.0.jar $HOME
    [dataexplorer1@r01edge sbttest]$ cd $HOME
    [dataexplorer1@r01edge ~]$ scala first_2.12-1.0.jar
    Hello world of sbt adventures
    
    
11. If the class cannot be found, set the classpath to the current directory:
    export CLASSPATH=.
    scala first_2.12-1.0.jar