Context-awareness refers to the idea that portable devices can keep track of their context, of the user's surroundings, in order to supply the user with relevant services. The Event-Control-Action (ECA) architectural pattern can be used to give structure to context-aware applications by specifying a way for them to process their data and act upon it by means of simple if-then-constructs. These constructs, or rules, can be specified using the ECA Domainspecific Language (ECA-DL). Currently, there exists no interpreter for this language. The Java Expert System Shell (Jess) is a rule engine for Java. A rule engine is a program that tries to match rules against information and then triggers one or more actions. This rule engine supports the Jess language. This book presents how the Model-Driven Architecture (MDA) approach can be used to develop a mapping between ECA-DL and the Jess language, and how to set up an automated transformation from ECA-DL rules to Jess rules, using this mapping. This automated transformation enables context-aware applications to use ECA-DL rules in an already existing interpreter, i.e., the Jess engine.