A method, system, and article for automated processing of a data stream are provided. Stream processing is applied to a hierarchical self describing data stream. As the data stream is processed, some elements therein are associated with a selected path expression. The selected path expressions are ordered based upon the hierarchy, and a tree structure is created that corresponds to the hierarchy. Each leaf node of the tree is associated with a logical operator or an expression to be applied to data processed from the data stream to the leaf node.