add drill02 ex 1 & 2

src/main/kotlin/drills/drill02/exercise1/Client.kt

@@ -0,0 +1,25 @@
+package drills.drill02.exercise1
+
+import util.rmi.Client
+
+fun main() {
+    Client(clientHandler).start()
+}
+
+val clientHandler = {
+    val chat = Client.lookup("chat") as RemoteObservable
+
+    val observer: RemoteObserver = ChatObserver()
+    chat.attach(observer)
+
+    print("Send> ")
+    var line = readLine() ?: "."
+
+    while (line != ".") {
+        chat.notify(line)
+        println("Send> ")
+        line = readLine() ?: "."
+    }
+
+    chat.detach(observer)
+}

src/main/kotlin/drills/drill02/exercise1/RemoteObservable.kt

@@ -0,0 +1,34 @@
+package drills.drill02.exercise1
+
+import java.rmi.Remote
+import java.rmi.RemoteException
+import java.rmi.server.UnicastRemoteObject
+
+interface RemoteObservable : Remote {
+    @Throws(RemoteException::class)
+    fun attach(o: RemoteObserver)
+
+    @Throws(RemoteException::class)
+    fun detach(o: RemoteObserver)
+
+    @Throws(RemoteException::class)
+    fun notify(obj: Any)
+}
+
+abstract class AbstractRemoteObservable : RemoteObservable, UnicastRemoteObject() {
+    private val observers = mutableListOf<RemoteObserver>()
+
+    override fun attach(o: RemoteObserver) {
+        observers.add(o)
+    }
+
+    override fun detach(o: RemoteObserver) {
+        observers.remove(o)
+    }
+
+    override fun notify(obj: Any) {
+        observers.forEach {
+            it.update(obj)
+        }
+    }
+}

src/main/kotlin/drills/drill02/exercise1/RemoteObserver.kt

@@ -0,0 +1,16 @@
+package drills.drill02.exercise1
+
+import java.rmi.Remote
+import java.rmi.RemoteException
+import java.rmi.server.UnicastRemoteObject
+
+interface RemoteObserver : Remote {
+    @Throws(RemoteException::class)
+    fun update(obj: Any)
+}
+
+class ChatObserver : RemoteObserver, UnicastRemoteObject() {
+    override fun update(obj: Any) {
+        println("Received> ${obj as String}")
+    }
+}

src/main/kotlin/drills/drill02/exercise1/Server.kt

@@ -0,0 +1,10 @@
+package drills.drill02.exercise1
+
+import util.rmi.Server
+
+fun main() {
+    Server {
+        val chat = object : AbstractRemoteObservable() {}
+        Server.bind(chat, "chat")
+    }.start()
+}

src/main/kotlin/drills/drill02/exercise2/Client.kt

@@ -0,0 +1,26 @@
+package drills.drill02.exercise2
+
+import util.rmi.Client
+
+fun main() {
+    Client(clientHandler).start()
+}
+
+val clientHandler = {
+    val rev = Client.lookup("rev") as Rev
+
+    println("Enter two numbers:")
+    val a = readLine()?.toInt() ?: 0
+    val b = readLine()?.toInt() ?: 0
+
+    val sum = rev.executeTask { a + b }
+    println("The sum of $a and $b is $sum")
+
+    println("Enter the number of which you want to calculate the factorial:")
+    val n = readLine()?.toInt() ?: 0
+
+    val fact = rev.executeTask { fact(n) }
+    println("The factorial of $n is $fact")
+}
+
+fun fact(n: Int): Long = if (n <= 1) 1 else n * fact(n - 1)

src/main/kotlin/drills/drill02/exercise2/Rev.kt

@@ -0,0 +1,14 @@
+package drills.drill02.exercise2
+
+import java.rmi.Remote
+import java.rmi.RemoteException
+import java.rmi.server.UnicastRemoteObject
+
+interface Rev : Remote {
+    @Throws(RemoteException::class)
+    fun <T> executeTask(task: () -> T): T
+}
+
+class RevImpl : Rev, UnicastRemoteObject() {
+    override fun <T> executeTask(task: () -> T): T = task()
+}

src/main/kotlin/drills/drill02/exercise2/Server.kt

@@ -0,0 +1,10 @@
+package drills.drill02.exercise2
+
+import util.rmi.Server
+
+fun main() {
+    Server {
+        val rev: Rev = RevImpl()
+        Server.bind(rev, "rev")
+    }.start()
+}

src/main/kotlin/util/rmi/Server.kt

@@ -25,9 +25,9 @@ class Server(private val handler: () -> Unit) {
     }
 
     companion object {
-        fun bind(remote: Remote, name: String, port: Int = 4242) {
+        fun bind(remote: Remote, name: String, host: String = "localhost", port: Int = 4242) {
             LocateRegistry.createRegistry(port)
-            Naming.bind("rmi://localhost:$port/$name", remote)
+            Naming.bind("rmi://$host:$port/$name", remote)
         }
     }
 }