Various technologies and techniques are disclosed for enabling code to be executed on one or more execution contexts based upon declarative annotations contained in the code or other locations. An annotation associated with a region of code is located. The annotation specifies information about an execution context where the region of code should be executed. A caller proxy is generated that is responsible for calling a callee adapter to execute the region of code. The callee adapter is generated that is responsible for receiving a call from the caller proxy and for dispatching a call to the region of code at the execution context. At runtime, the caller proxy receives a request to call the region of code and sends an execution request to the callee adapter. The callee adapter receives the execution request and dispatches a call to an executable version of the region of code.