Red5 + Java + Windows installation + ant compilation: it works, but why?

I am completely new to the java and java Server worlds ... But I have good knowledge (17 years) of object oriented programming. My question is:

Why do I need to call ant for it to work (see later, if you're not interested, skip my question ^ _ ^)?

Here I want to: create a simple application that can do video conferencing (= server receives one client video stream and sends it to client X). I wanted it for free (Adobe Server costs roughly $ 10,000). The only solution I have found is Red5 (see there )

I downloaded and installed version 0.7. Here are the steps I took to successfully compile java app for Red5:

• download and install (Windows XP) latest version (0.7)
• Download and copy manually to install folder with some files forgotten in 0.7 install (compare to v0.6 release and guess which ones) ( ivy.xml
  
  if I remember)
• go to the folder [Red5 path]\webapps
  
  . Copy / paste the folder tutorial
  
  .
• rename the folder to myapp
  
  .
• edit all xml files in this folder, find the line tutorial
  
  and rename it tomyapp
  
  
• here is what i did and did not work: compile with javac:
  javac -classpath "[Red5 path]\red5.jar" -d "[Red5 path]\webapps\myapp\WEB-INF\classes" Application.java javac -classpath "[Red5 path]\red5.jar" -d "[Red5 path]\webapps\myapp\WEB-INF\classes" TestService.java
  
  
• Everything worked fine, but as soon as I started the Flex client the response from the server was "Invalid application"

• After many tries I found that removing everything except this code works:

  package myapp;
  
  import org.red5.server.adapter.ApplicationAdapter;
  import org.red5.server.api.IConnection;
  import org.red5.server.api.IScope;    
  
  /* myapp */
  public class Application extends ApplicationAdapter {
  
  
        
  
          
          
          
        
  
      

  public String sayHello(Object[] params){
      return "got : " + params[0].toString();
  }
  
        
  
          
          
          
        
  
      
        
  
          
          
          
        
  
      

  } >
  
  

Then I then wanted to follow.

• I wrote some code that worked in Red5 examples:
  
  
  

  
  package myapp;
        
  
          
          
          
        
  
      

  
  
  

  import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.red5.server.adapter.ApplicationAdapter; import org.red5.server.api.IConnection; import org.red5.server.api.IScope;

  public class Application extends ApplicationAdapter {

  protected static Logger log = LoggerFactory.getLogger(Application.class);
  
  public String sayHello(Object[] params){
      log.info("I got your name: "+params[0].toString());
      return "I got your name: " + params[0].toString();
  }
  
        
  
          
          
          
        
  
      

  } Code>

• After restarting server Red5: I always got this response from the server: "Invalid application"

• Then I downloaded ant , unpacked it into[Red5 path]
  
  
• I created a new file [Red5 path]\webapps\myapp\WEB-INF\build.xml
  
  
• I added this xml to it:

<project name="Projet myapp" default="compile" basedir=".">
    <target name="clean" description="Clean output directories">
    </target>
    <target name="compile" depends="clean">
        <javac srcdir="./src" destdir="./classes" source="1.6" classpath="C:\Program Files\Red5\red5.jar" >
        </javac>
    </target>
    <target name = "jar" depends ="compile">
        <echo message ="Creating jar..."/>
        <jar destfile="./lib/myapp.jar" basedir="./classes"/>
        <echo message ="Done."/>
    </target>
</project>

      

        
        
        
      

    

6. Start a shell, then enter:
   
   
   

   cd [Red5 path]\webapps\myapp\WEB-INF
   ......\apache-ant-1.7.1\bin\ant jar
         
   
           
           
           
         
   
       

   
   
   
7. Everything works perfectly!
8. Here is the question!
9. I don't understand:
   Why would I call ant to make it work?