EGL, originally developed by IBM and now available as the EDT Open Source project under the Eclipse Public License, is a programming technology designed to meet the challenges of modern, multi-platform application development by providing a common language and programming model across languages, frameworks, and runtime platforms. The language borrows concepts familiar to anyone using statically typed languages like Java, COBOL, C, etc. However, it borrows the concept of stereotype from Unified Modeling Language that is not typically found in statically typed programming languages. In a nutshell, EGL is a higher-level, universal application development language. 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:
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. Program functions are composed of a set of EGL statements, variables, and constants. Program HelloWorld const GREETING string = "Hello, ";
function main myName string = "John"; sayHello; end function sayHello SysLib.writeStdOut; 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 EMPNUMBER string; FIRSTNME string; MIDINIT string; LASTNAME string; DEPT string; PHONENO string; HIREDATE date; end
In this example, the record Employee is bound to a table 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 records Employee; // define an empty array of records get records; // retrieve records from the database return ; // return the records end
function addEmployee returns try add remp; return ; onException return ; end end end
In EGL, code is organized in packages
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
The main component of a Rich UI application is a Rich UI handler part. These parts are generated into JavaScript. package com.mycompany.ui; import com.mycompany.services.Employee; import com.mycompany.services.EmployeeService; import dojo.widgets.DojoGrid; import dojo.widgets.DojoGridColumn; handler EmployeeView type RUIhandler grid DojoGrid ; function start svc EmployeeService ; call svc.getEmployees returning to displayEmployees; end function displayEmployees grid.data = retResult as any ; end
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.
a set of conversion tools available within the Rational Business Developer product provide automated the conversion from older and stabilized IBM and Informix4th generation languages
a set of IBM service offerings and complementary products provide the ability to convert from Software AG Natural, IBM RPG, CA Cool:Gen and CA Ideal/Datacom to EGL
Tools for searching large EGL code bases, comparing individual EGL files for changes, and detecting duplicated code are available from Semantic Designs
Books on EGL
Enterprise Web 2.0 with EGL,.
Developing Web 2.0 Applications with EGL for IBM i,.
