Learning object specification and description of pedagogical resources in respect to material structure and content

Nowadays, many E-Learning systems are currently available on the Web with various types of learning resources. Website becomes one of important communication lines between teacher and student. For teachers to prepare their courses, searching and collecting learning resources will be necessary in the primary step. Imagine in database scope, there are many courses that concerned with database in many levels, for example: introduction to database, database system principles, advanced topics in database systems, and database system implementation. Each courses are different in difficulty level but they are shared the same basic concept. For teachers who prepare these database courses, it is possible that they will use or refer to the same materials. The question is what is the effective way to share their materials or pedagogical resources? And for their own courses, how to representation these courses with several types of resources?