Anggoro,
As a former JDE OneWorld developer, you'll find that the development tools themselves haven't changed too much (form design, report design, table design, view design, etc.). The big change you'll probably notice is that the old Object Librarian has been replaced with the Object Management Workbench (aka OMW). This is the program in which you control the objects you work on project-by-project, lets you check objects in and out, and promote them from one environment to another. All of this still has to run on a fat client (now called a development client), which now also includes a local web server for testing changes locally before deploying to servers.
It would probably be worth your while to take some JDE Developer training to formally brush up on what's new and how best to use the current JDE development tools available.