distributed applications is difficult to write as a programmer needs to adhere to specific distributed systems programming conventions and frameworks, which makes distributed development of complex and error-prone system and application relationships generated by a distributed system because the application code is tangled with the distribution of crosscutting concerns. This book introduces the concept of domain-specific aspect language called a Distribution Definition Language which generalises distribution concerns the distribution and recovery by describing classes and methods to an existing application to be made remote, distributed systems to be used to make them isolated and recovery mechanisms to be used at the time an error occurred.