1. A computer-implemented method, comprising: operating an execution environment comprising instances of application components and a registry that maps names to instances of application components; while operating the execution environment, upon receiving a call to register a mapping between a name and an instance of an application component, updating the registry to include an entry for the mapping; and upon receiving a call to be notified about registry changes for a name, updating the registry to send a notification to a caller when a registry change occurs for the name.