--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/progs/Application0.scala	Tue Sep 24 12:23:54 2013 +0100
@@ -0,0 +1,23 @@
+package controllers
+
+import play.api.mvc._
+
+// hello world program: 
+// just answer the GET request with a string
+
+object Application extends Controller {
+
+  // answering a GET request
+  val index = Action { request =>
+
+    Ok("Hello world!")
+  }  
+  
+}
+
+/*
+ * HTML can be returned using
+ *
+ * Ok("<H1>Hello world!</H1>").as(HTML)
+ *
+ */ 

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/progs/Application1.scala	Tue Sep 24 12:23:54 2013 +0100
@@ -0,0 +1,39 @@
+package controllers
+
+import play.api._
+import play.api.mvc._
+import play.api.data._
+import play.api.data.Forms._
+
+/*
+ * Answers a GET-request by sending a simple login form.
+ *
+ * Processes the POST-data by just printing the results.
+ *
+ */
+
+object Application extends Controller {
+
+  // GET request -> login form
+  val index = Action { request =>
+    
+    val form = """
+               <form method="post"> 
+               Login: <input type="text" name="login"><br>
+               Password: <input type="password" name="password"><br>
+               <input type="submit"></form>"""
+
+    Ok(form).as(HTML)
+  }  
+
+  
+  // POST data: processing the login data
+  val receive = Action { request =>
+    
+    val form_data = Form(tuple ("login" -> text, "password" -> text))
+    val (login, password) = form_data.bindFromRequest()(request).get 
+    
+    Ok(s"Received login: $login and password: $password")
+  }
+  
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/progs/Application2.scala	Tue Sep 24 12:23:54 2013 +0100
@@ -0,0 +1,43 @@
+package controllers
+
+import play.api.mvc._
+
+/*
+ * Application sets a cookie in plain ASCII on the
+ * client's browser recording the number of visits
+ * of a page.
+ */
+
+object Application extends Controller {
+
+  //no or invalid cookie results in the counter being 0
+  def gt_cookie(c: Cookie) : Int = c.value match {
+    case s if (s.forall(_.isDigit)) => s.toInt 
+    case _ => 0
+  }
+
+  def mk_cookie(i: Int) : Cookie = {
+    Cookie("visits", i.toString)
+  }
+  
+  // GET request: read cookie data first
+  def index = Action { request =>
+ 
+    //reads the cookie and extracts the visits counter   
+    val visits_cookie = request.cookies.get("visits")
+    val visits = visits_cookie.map(gt_cookie).getOrElse(0)
+
+    //printing a message according to value of visits counter
+    val msg = 
+      if (visits >= 10)
+        s"You are a valued customer who has visited this site $visits times."               
+      else s"You have visited this site $visits times."
+    
+    //send message with new cookie
+    Ok(msg).withCookies(mk_cookie(visits + 1))
+  }
+}
+
+
+
+

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/progs/Application3.scala	Tue Sep 24 12:23:54 2013 +0100
@@ -0,0 +1,50 @@
+package controllers
+
+import play.api.mvc._
+import java.security.MessageDigest
+
+/*
+ * Application sets a cookie in plain ASCII on the
+ * clients browser recording the visits of a page.
+ *
+ * The cookie data is hashed and stored in the format:
+ *
+ * visits_counter/hashed_value 
+ */
+
+object Application extends Controller {
+
+  //hash functions: SHA-1, SHA-256, etc
+  def mk_hash(s: String) : String = {
+    val hash_fun = MessageDigest.getInstance("SHA-1")
+    hash_fun.digest(s.getBytes).map{ "%02x".format(_) }.mkString
+  }
+
+  //extracting from the string .../... the visits
+  //value and hash
+  def gt_cookie(c: Cookie) : Int = c.value.split("/") match {
+    case Array(s, h) if (s.forall(_.isDigit) && mk_hash(s) == h) => s.toInt 
+    case _ => 0
+  }
+
+  def mk_cookie(i: Int) : Cookie = {
+    val hash = mk_hash(i.toString)
+    Cookie("visits", s"$i/$hash")
+  }
+   
+  def index = Action { request =>
+    val visits_cookie = request.cookies.get("visits")
+    val visits = visits_cookie.map(gt_cookie).getOrElse(0)
+
+    val msg = 
+      if (visits >= 10)
+        s"You are a valued customer who has visited this site $visits times."               
+      else s"You have visited this site $visits times."
+    
+    Ok(msg).withCookies(mk_cookie(visits + 1))
+  }     
+}
+
+
+
+

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/progs/Application4.scala	Tue Sep 24 12:23:54 2013 +0100
@@ -0,0 +1,52 @@
+package controllers
+
+import play.api.mvc._
+import java.security.MessageDigest
+
+/*
+ * Application sets a cookie in plain ASCII on the
+ * clients browser recording the visits of a page.
+ *
+ * The cookie data is hashed and salted with a
+ * secret key.
+ */
+
+
+object Application extends Controller {
+
+  //secret key for salting 
+  val salt = "my secret key"
+
+  //SHA-1 + salt
+  def mk_hash(s: String) : String = {
+    val hash_fun = MessageDigest.getInstance("SHA-1")
+    hash_fun.digest((s + salt).getBytes).map{ "%02x".format(_) }.mkString
+  }
+
+  def gt_cookie(c: Cookie) : Int = c.value.split("/") match {
+    case Array(s, h) if (s.forall(_.isDigit) && mk_hash(s) == h) => s.toInt 
+    case _ => 0
+  }
+
+  def mk_cookie(i: Int) : Cookie = {
+    val hash = mk_hash(i.toString)
+    Cookie("visits", s"$i/$hash")
+  }
+   
+  def index = Action { request =>
+
+    val visits_cookie = request.cookies.get("visits")
+    val visits = visits_cookie.map(gt_cookie).getOrElse(0)
+
+    val msg = 
+      if (visits >= 10)
+        s"You are a valued customer who has visited this site $visits times."               
+      else s"You have visited this site $visits times."
+    
+    Ok(msg).withCookies(mk_cookie(visits + 1))
+  }     
+}
+
+
+
+