  The massive semantic data sources linked in the Web of Data give new meaning
to old features like navigation; introduce new challenges like semantic
specification of Web fragments; and make it possible to specify actions relying
on semantic data. In this paper we introduce a declarative language to face
these challenges. Based on navigational features, it is designed to specify
fragments of the Web of Data and actions to be performed based on these data.
We implement it in a centralized fashion, and show its power and performance.
Finally, we explore the same ideas in a distributed setting, showing their
feasibility, potentialities and challenges.
