EGL (programming language)

EGL (Enterprise Generation Language) is a high level, modern business oriented programming language, designed by IBM to be platform independent. EGL is similar in syntax to other common languages so it can be learned by application developers with similar previous programming background. EGL application development abstractions shield programmers from the technical interfaces of systems and middleware allowing them to focus on building business functionality. EGL applications and services are written, tested and debugged at the EGL source level, and once they are satisfactorily functionally tested they can be compiled into COBOL, Java, or JavaScript code to support deployment of business applications that can run in any of the following environments:

Microsoft Windows, Linux, UNIX running JVM, for example in the context of a Java EE servlet container (IBM WebSphere Application Server, Apache Tomcat, GlassFish)
IBM System z: CICS Transaction Server, IMS, z/OS Batch, UNIX System Services, WebSphere Application Server, z/VSE, Linux
IBM System i: IBM i5/OS, IBM WebSphere Application Server, Apache Tomcat
Internet Explorer, Firefox, Safari browsers for Ajax rich web applications

Code examples

Program

An EGL Program part is a generatable logic part with one entry point. Each Program part contains a main() function, which represents the logic that runs at program start up. A program can include other functions and can access functions that are outside of the program. The function main() can invoke those other functions. Programs functions are composed of a set of EGL statements, variables, and constants.

Program HelloWorld

	const GREETING string = "Hello, ";
    
	function main()
		myName string = "John";
		sayHello(myName);
	end     

	function sayHello(name String in)
		SysLib.writeStdOut(GREETING + name + "!");
	end

end

Record

An EGL Record part defines a set of data elements. In this example, a record with the name CustomerRecord is defined with 6 fields.

Record CustomerRecord type BasicRecord
	customerNumber INT;            
	customerName STRING;
	customerAddr1 STRING;
	customerAddr2 STRING;
	customerAddr3 STRING;
	customerBalance MONEY;
end

EGL has a specialized type of record called SQLRecord that is used to exchange data with a relational database.

record Employee type sqlRecord { tableNames =[["Employee"]
            ], keyItems =[EMPNO]}
    EMPNUMBER string{ column = "EMPNO", maxLen = 6};
    FIRSTNME string{ sqlVariableLen = yes, maxLen = 12};
    MIDINIT string{ isSqlNullable = yes, maxLen = 1};
    LASTNAME string{ sqlVariableLen = yes, maxLen = 15};
    DEPT string{ column = "WORKDEPT", isSqlNullable = yes, maxLen = 3};
    PHONENO string{ isSqlNullable = yes, maxLen = 4};
    HIREDATE date{ isSqlNullable = yes};
end

In this example, the record Employee is bound to a table (or view) named Employee.

Service

An EGL Service part contains public functions meant to be accessed from other applications or systems. In this example, a service with two functions is defined.

package com.mycompany.services;

service EmployeeService

    function getEmployees() returns(Employee[])
        records Employee[0]; // define an empty array of records
        get records; // retrieve records from the database
        return (records); // return the records       
    end
    
    function addEmployee(emp Employee in) returns (boolean)
    	try
    		add emp;
    		return (true);
    	onException (ex AnyException)
    		return (false);
    	end
    end

end

In EGL, code is organized in packages (like Java (programming language))
The first function, getEmployees, returns an array of records populated from the records in a database.
The second function, addEmployee adds a new record to the database and returns a true or false depending on whether the record was added successfully.

RUIHandler

Web 2.0 with EGL

In December 2008, IBM introduced new technology, EGL Rich UI, to simplify the creation of Web 2.0-style Rich Internet Applications. This technology simplifies development by hiding the complexities of Ajax, JavaScript, Rest, and SOAP from the developer, which enables them to focus on the business requirement and not on the underlying technologies.

Commercial Products

EGL programming tools are available as an Eclipse-based commercial product, the Rational Business Developer and also in the EGL edition of Rational Developer for System z.

EGL is a target language for modernization of legacy applications because of the language semantics affinity with procedural languages and legacy 4th generation languages:

a set of conversion tools available within the Rational Business Developer product provide automated the conversion from older and stabilized IBM and Informix 4th generation languages
a set of IBM service offerings and complementary products (Rational Migration Extension for Natural, Rational Migration Extension for System i) provide the ability to convert from Software AG Natural and from IBM RPG to EGL

External links

Books on EGL

Enterprise Web 2.0 with EGL, ISBN 978-1-58347-091-6.
Developing Web 2.0 Applications with EGL for IBM i, ISBN 978-1-58347-089-3.