Constraint logic programming (CLP) languages combine constraint solving and logic programming [5]. Earlier CLP systems include CHIP, CLP(R), and Prolog-III. Many Prolog systems, such as B-Prolog, Sicstus-Prolog, and Eclipse, support constraint solving over some domains. DJ is implemented in B-Prolog, but it is more than another syntactical sugar for CLP. DJ is object-oriented and provides arrays and many graphic classes. The lack of arrays and the object-oriented feature in CLP has long been considered a serious shortcoming. Compared with CLP languages, DJ is a domain-specific language. DJ is well suited for developing applets to be embedded in some Web documents and/or integrated into some larger applications.