Significant changes made in the earlier (foundational) chapters of the book in recognition of the increasing diversity of distributed systems — particularly in terms of the range of architectural approaches available to distributed systems developers today. Three entirely new chapters: Chapter 6 Indirect Communication: Includes events and notification from 4th ed. Chapter 8 Distributed Objects and Components: Includes precised version of the CORBA case study from 4th ed. Chapter 21 Designing Distributed Systems: Includes major new case study on Google Substantial changes to a number of other chapters include: Chapter 1 Characterization of DS: Significant restructuring of material: New section 1.2: Examples of dist. systems; Section 1.2.2: Cloud computing introduced Chapter 2 System Models: Significant restructuring of material: New Section 2.2: Physical models; Section 2.3: major re-write to reflect new book content and associated architectural perspectives Chapter 4 Interprocess Communication: Several updates: Client-server comm. moved to Chapter 5; New Section 4.5: Network virtualization (includes case study on Skype); New Section 4.6: Case Study on MPI; Case study on IPC in UNIX removed Chapter 5Remote Invocation: Significant restructuring of materia:l Client-server comm. moved to here; Progression introduced from client-server communication through RPC to RMI; Events and notification moved to Chapter 6 Many of the chapters have been changed to reflect new information that has become available about the systems described. The authors have placed material removed from the fourth edition, as well as material removed from previous editions, on the book's Companion web site. This includes the case studies on ATM, inter-process communication in UNIX, CORBA (a shortened version of this case study remains in Chapter 8), the Jini distributed events specification, the chapter on distributed shared memory (a brief summary of this area is included in Chapter 6),and the case study of Grid middleware (featuring OGSA and the Globus toolkit).