David Gibbs wrote:

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?

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);

Record HelloRequest type BasicRecord
10 Name char(30);

Record HelloResponse type BasicRecord
10 Salutation char(40);

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 {} };

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
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 ) );
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 )}) ) );
public void $initSayHello( SayHello ezeProgram ) throws Exception
_dbms( com.ibm.javart.sql.Sql.DBMS_DB2 );
// name = "Joe";
com.ibm.javart.operations.Assign.run( ezeProgram, ezeProgram.name, "Joe" );

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


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