Getting started with liftweb framework

Required 
Java
maven2 or sbt
jetty - a Java servlet engine
scala

STEP 1 Install Java and configure PATH
http://www.oracle.com/technetwork/java/javase/downloads/jdk7u9-downloads-1859576.html

STEP 2 Install scala 2.9.2
Download scala from http://www.scala-lang.org/downloads

$ wget  http://www.scala-lang.org/files/archive/scala-2.9.2.tgz

$ sudo mkdir /opt/scala292
Open the dowloaded file (Archive manager - file-roller) and extract to /opt/scala/

Create a sybolic link (future proof the install):
$ ln -s /opt/scala/scala-2.9.2 /opt/scala292/current

Define environment variable SCALA_HOME by editing /etc/profile and adding the line:
export SCALA_HOME=/opt/scala292/current

Add the Scala executables to your path by editing /etc/profile and adding the line:
export PATH=$PATH:$SCALA_HOME/bin

restart computer, and enter command
scala -version
Scala code runner version 2.9.2  -- Copyright 2002-2011, LAMP/EPFL


STEP 3 Install maven
$ sudo apt-get install maven2

OR
Download maven from http://maven.apache.org/download.html and configure PATH.
(mine /etc/profile is)

JAVA_HOME=/usr/java/jdk1.7.0; export JAVA_HOME
PATH=$JAVA_HOME/bin:$PATH; export PATH
export PATH=$PATH:/home/prayag/apache-maven-3.0.4/bin


STEP 4 Install jetty, an HTTP server, HTTP client, and javax.servlet container
$ sudo apt-get install jetty


STEP 5 Create liftweb app with mvn
$ mkdir /home/prayag/workspace_lift
$ cd /home/prayag/workspace_lift

Issue the following maven2 command for a lift project template downloaded from http://scala-tools.org/repo-snapshots :

mvn archetype:generate \
 -DarchetypeGroupId=net.liftweb \
 -DarchetypeArtifactId=lift-archetype-basic_2.9.1 \
 -DarchetypeVersion=2.4-M5 \
 -DarchetypeRepository=http://scala-tools.org/repo-releases \
 -DremoteRepositories=http://scala-tools.org/repo-releases \
 -DgroupId=com.zam.gwitter \
 -DartifactId=gwitter \
 -Dversion=1.0

The architecture of app will be as follows :

5 - A) The dependencies in pom.xml will be as follows :

<repositories>
    <repository>
      <id>scala-tools.releases</id>
      <name>Scala-Tools Dependencies Repository for Releases</name>
      <url>http://scala-tools.org/repo-releases</url>
    </repository>
    <repository>
      <id>java.net.maven2</id>
      <name>java.net Maven2 Repository</name>
      <url>http://download.java.net/maven/2/</url>
    </repository>
  </repositories>

  <pluginRepositories>
    <pluginRepository>
      <id>scala-tools.releases</id>
      <name>Scala-Tools Plugins Repository for Releases</name>
      <url>http://scala-tools.org/repo-releases</url>
    </pluginRepository>
  </pluginRepositories>

  <dependencies>
    <dependency>
      <groupId>net.liftweb</groupId>
      <artifactId>lift-mapper_2.9.1</artifactId>
      <version>2.4-M5</version>
    </dependency>
    <dependency>
      <groupId>ch.qos.logback</groupId>
      <artifactId>logback-classic</artifactId>
      <version>0.9.26</version>
    </dependency>
    <dependency>
      <groupId>com.h2database</groupId>
      <artifactId>h2</artifactId>
      <version>1.2.138</version>
      <scope>runtime</scope>
    </dependency>
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>servlet-api</artifactId>
      <version>2.5</version>
      <scope>provided</scope>
    </dependency>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.7</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>org.scala-tools.testing</groupId>
      <artifactId>specs_2.9.1</artifactId>
      <version>1.6.9</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>org.mortbay.jetty</groupId>
      <artifactId>jetty</artifactId>
      <version>6.1.25</version>
      <scope>test</scope>
    </dependency>
    <!-- for LiftConsole -->
    <dependency>
      <groupId>org.scala-lang</groupId>
      <artifactId>scala-compiler</artifactId>
      <version>${scala.version}</version>
      <scope>test</scope>
    </dependency>
  </dependencies>

5 - B) The gwitter/src/main/webapp/WEB-INF/web.xml file will be as follows :

<?xml version="1.0" encoding="ISO-8859-1"?>

<!DOCTYPE web-app
PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
"http://java.sun.com/dtd/web-app_2_3.dtd">

<web-app>
<filter>
  <filter-name>LiftFilter</filter-name>
  <display-name>Lift Filter</display-name>
  <description>The Filter that intercepts lift calls</description>
  <filter-class>net.liftweb.http.LiftFilter</filter-class>
</filter>
   

<filter-mapping>
  <filter-name>LiftFilter</filter-name>
  <url-pattern>/*</url-pattern>
</filter-mapping>

</web-app>

5 - C) The gwitter/src/main/webapp/index.html will be as follows :

<div class="lift:surround?with=default;at=content">
  <h2>Welcome to your project!</h2>
  <p>
    <div class="lift:helloWorld.howdy">
      Welcome to gwitter at <span id="time">The current time</span>
    </div>
  </p>
</div>

5 - D) The com/zam/gwitter/model/User.scala will be as follows :

package com.zam.gwitter {
package model {

import _root_.net.liftweb.mapper._
import _root_.net.liftweb.util._
import _root_.net.liftweb.common._

/**
 * The singleton that has methods for accessing the database
 */
object User extends User with MetaMegaProtoUser[User] {
  override def dbTableName = "User" // define the DB table name
  override def screenWrap = Full(<lift:surround with="default" at="content">
          <lift:bind /></lift:surround>)
  // define the order fields will appear in forms and output
  override def fieldOrder = List(id, firstName, lastName, email,
  locale, timezone, password, textArea)

  // comment this line out to require email validations
  override def skipEmailValidation = true
}

/**
 * An O-R mapped "User" class that includes first name, last name, password and we add a "Personal Essay" to it
 */
class User extends MegaProtoUser[User] {
  def getSingleton = User // what's the "meta" server

  // define an additional field for a personal essay
  object textArea extends MappedTextarea(this, 2048) {
    override def textareaRows  = 10
    override def textareaCols = 50
    override def displayName = "Personal Essay"
  }
}
}
}

5 - E)  The com/zam/gwitter/snippet/HelloWorld.scala snippet will be as follows:

package com.zam.gwitter {
package snippet {

import _root_.scala.xml.{NodeSeq, Text}
import _root_.net.liftweb.util._
import _root_.net.liftweb.common._
import _root_.java.util.Date
import com.zam.gwitter.lib._
import Helpers._

class HelloWorld {
  lazy val date: Box[Date] = DependencyFactory.inject[Date] // inject the date

  // bind the date into the element with id "time"
  def howdy = "#time *" #> date.map(_.toString)

  /*
   lazy val date: Date = DependencyFactory.time.vend // create the date via factory

   def howdy = "#time *" #> date.toString
   */
}//end of class
}
}

5 - F)  The com/zam/gwitter/lib/DependencyFactory.scala will be as follows :

package com.zam.gwitter {
package lib {

import net.liftweb._
import http._
import util._
import common._
import _root_.java.util.Date

/**
 * A factory for generating new instances of Date.  You can create
 * factories for each kind of thing you want to vend in your application.
 * An example is a payment gateway.  You can change the default implementation,
 * or override the default implementation on a session, request or current call
 * stack basis.
 */
object DependencyFactory extends Factory {
  implicit object time extends FactoryMaker(Helpers.now _)

  /**
   * objects in Scala are lazily created.  The init()
   * method creates a List of all the objects.  This
   * results in all the objects getting initialized and
   * registering their types with the dependency injector
   */
  private def init() {
    List(time)
  }
  init()
}

/*
/**
 * Examples of changing the implementation
 */
sealed abstract class Changer {
  def changeDefaultImplementation() {
    DependencyFactory.time.default.set(() => new Date())
  }

  def changeSessionImplementation() {
    DependencyFactory.time.session.set(() => new Date())
  }

  def changeRequestImplementation() {
    DependencyFactory.time.request.set(() => new Date())
  }

  def changeJustForCall(d: Date) {
    DependencyFactory.time.doWith(d) {
      // perform some calculations here
    }
  }
}
*/
}
}

STEP 6 Run a liftweb app
Issue mvn jetty:run and access the web application in your browser via http://localhost:8080

STEP 7 RESULT

REFERENCES
1 - Lift + Scala, Installation + First contact, 11. AUGUST 2010 available at http://tuxpool.blogspot.com/2010/08/lifting-scala-installation-first.html

2 - Using Maven, available at https://www.assembla.com/wiki/show/liftweb/Using_Maven