This technical paper presents an online Java compilation plug-in for the Moodle Learning Management System. The system allows students to compile and execute Java programs directly through the Moodle interface so that they can concentrate on the programming concepts rather than learning to operate new technologies. The system provides students with error diagnostics on compilation and execution so that they can more easily resolve their programming problems. Teachers can view compilation and execution data in order to analyze students’ programming performance, enabling them to not only provide more appropriate feedback but also to understand where student misconceptions occur. The technical aspects of the system are discussed in detail to support implementation and development by others. The rationale for the design in terms of providing a secure and cognitively efficient means of teaching computing programming is articulated.