Distributed Systems

Introduction

Out of the many possible definitions of a distributed system, we herein employ the following, which is perhaps the most general (and in particular supercedes Lamport's humorous remark that "a distributed system is the one that prevents you from working because of the failure of a machine that you had never heard of".):

Distributed System

A distributed system is comprised by a set of distributed (i.e., not located in the same spot)

components (hardware and/or software) working together to provide one service.

That is, there are two characteristics to a distributed system: (1) the service it provides emerges at the system level and (2) components cannot communicate directly, instead, they have to use communication links (which are components themselves).

Fault Tolerance

Distributed systems allow parts of the system to be located on separate computers and different locations. So business logic and data can be reached from any remote computer (location).

Distributed objects are the most recent development in distributed computing. Distributed object technologies such as Java RMI, CORBA, and DCOM allow objects running on one machine to be used by applications on different computers.