Re: Noob questions

[Joe Pluta <joepluta@xxxxxxxxxxxxxxxxx>]

David Gibbs wrote:
> Folks:
>
> In an effort to educate myself, I'm wondering if someone could answer a few questions about EGL for me.  Unfortunately I don't really have time to do the research myself at the moment, and this is only idle curiosity at the moment.
>
> 1. Can anyone point me to a sample of simple EGL and the generated Java / native iSeries code that EGL emits?  I admit to having a prejudice against code generators (chalk it up to being scared by using AS/SET for 4 years).
>   
I'll attach the code at the end of a simple program that invokes a web 
service and prints the result.  And while the Java is actually 
relatively readable, I raise the point that you don't look at the code 
unless the generator has a bug.  Other than that, you use the high-level 
EGL debugger which is very powerful.

> 2. I've been assuming that EGL has some runtime libraries that are required along with the compiled & generated code.  Is this correct?
>   
Yes.

> 3. If #2 is correct, what are the licensing & redistribution rules regarding the runtime libraries, if any?
>   
None.  If it's an EAR, export the EAR and run it.  The rich client 
JavaScript is even easier, just post the generated HTML on your favorite 
HTTP server.

> 4. Can someone point me to an basic example of EGL code that talks to a iSeries native program (perhaps via data queue) and does something for the client?
>   
This code calls an RPG program, passing two structure (each with one 
field, but we're keeping it simple).

package services;

service HelloService
   function hello(toWhom string in) returns (string)
       SysLib.setRemoteUser("RUI00001", "RUI00001");
       hrq HelloRequest { Name = toWhom };
       hrs HelloResponse;
       call "HELLO" ( hrq, hrs );
       return (hrs.Salutation);
   end
end

Record HelloRequest type BasicRecord
 10 Name char(30);
end

Record HelloResponse type BasicRecord
 10 Salutation char(40);
end


The RPG code simply defines two parameters, one of 30 char, one of 40 
char.  Done.  If it were more complex data, you would use a data 
structure and EGL would convert between the various types.

Note that I've defined this as a service.  That means it can be invoked 
by another EGL program, or if I choose I can generate a web service 
complete with WSDL that can be invoked by anyone.


And here's the simple code to invoke that web service:

package clients;
import interfaces.HelloService;

program SayHello type BasicProgram {}
  
   // Variable Declarations
   name string = "Joe";
  
   function main()
       iHelloService HelloService { @BindService {} };
       SysLib.writeStdout(iHelloService.hello(name));
   end
  
end

It generates this:

// Generated at Thu Jul 31 12:40:53 CDT 2008 by EGL 7.1.0.RFB_20080124_1622
package clients;

public class SayHello extends com.ibm.javart.resources.Program
{
   private static final long serialVersionUID = 70L;
  
   public final SayHello ezeProgram;
   public com.ibm.javart.StringValue name;
  
   public SayHello( com.ibm.javart.resources.RunUnit ru ) throws Exception
   {
       super( "SayHello", "SayHello", ru, false, true );
       ezeProgram = this;
       name = new com.ibm.javart.StringItem( "name", 
com.ibm.javart.Value.SQL_NOT_NULLABLE, 
com.ibm.javart.Constants.SIGNATURE_STRING );
       $initSayHello( this );
   }
  
   public void _start() throws Exception
   {
       $func_main();
      
   }
   public static com.ibm.javart.resources.StartupInfo _startupInfo()
   {
       return new com.ibm.javart.resources.StartupInfo( "SayHello", 
"clients/SayHello.properties", false );
   }
   public static void main( String[] args ) throws Exception
   {
       com.ibm.javart.resources.StartupInfo info = _startupInfo();
       info.setArgs( args );
       com.ibm.javart.resources.RunUnit ru = new 
com.ibm.javart.resources.RunUnit( info );
       ru.start( new SayHello( ru ) );
       ru.exit();
   }
  
   public void $func_main() throws Exception
   {
       _funcPush( "main" );
      
       // iHelloService HelloService;
       com.ibm.javart.ref.ServiceReferenceRef iHelloService = new 
com.ibm.javart.ref.ServiceReferenceRef( "iHelloService", 
_runUnit().getServiceBinder().bindService( ezeProgram, "HelloService", 
"testservice" ), "Tinterfaces/HelloService;" );
       // SysLib.writeStdout(iHelloService.hello(name));
       System.out.println( 
com.ibm.javart.operations.ConvertToString.run( ezeProgram, 
iHelloService.checkedValue( ezeProgram ).ezeInvoke("hello", 
"$func_hello", new com.ibm.javart.calls.MethodParameter[] { new 
com.ibm.javart.calls.MethodParameter( 
com.ibm.javart.operations.Assign.run( ezeProgram, new 
com.ibm.javart.StringItem( "toWhom", 
com.ibm.javart.Value.SQL_NOT_NULLABLE, 
com.ibm.javart.Constants.SIGNATURE_STRING ), ezeProgram.name ), 1 ), new 
com.ibm.javart.calls.MethodParameter( new com.ibm.javart.StringItem( 
"STRING", com.ibm.javart.Value.SQL_NOT_NULLABLE, 
com.ibm.javart.Constants.SIGNATURE_STRING ), 0 )}) ) );
       // RETURN
       _funcPop();
       return;
   }
  
   public void $initSayHello( SayHello ezeProgram ) throws Exception
   {
       egl__vg__VGVar.handleOverflow.setValue(1);
       _dbms( com.ibm.javart.sql.Sql.DBMS_DB2 );
       // name = "Joe";
       com.ibm.javart.operations.Assign.run( ezeProgram, 
ezeProgram.name, "Joe" );
       // RETURN
   }
  
}


Not pretty, perhaps, but readable and again, you don't spend any time in 
this.

Joe