Imperative languages perform computations as sequences of steps and changes of values stored in memory. Programming language based on the predicate calculus and logical deductions. There are very few purely functional languages. Database languages Different from most other programming languages in that database entities remain after the programs end. Contain features of the block structure paradigm.
Classes contain data.
Horizontal dimension presents the classifier roles that represent individual objects in the collaboration. Each classifier role is represented by a vertical column the lifeline . During the time an activation of a procedure on the object is active the lifeline is drawn as a double line. A message is shown as an arrow from the lifeline of one object to that of another. The arrows are arranged in time sequence down the diagram.