In this technological era, failure to address application-layer fault-tolerance, a key ingredient to crafting truly dependable computer services, leaves the door open to unfortunate consequences in quality of service. Application-Layer Fault-Tolerance Protocols increases awareness of the need for application-layer fault-tolerance (ALFT) through introduction of problems and qualitative analysis of solutions. A necessary read for researchers, practitioners, and students in dependability engineering, this book collects emerging research to offer a systematic, critical organization of the current knowledge in ALFT.