"wholerather" - 1 õppematerjal

IT arhitektuur

·Components are not shared by all users ·Resources may not be accessible ·Software runs in concurrent processes on different processors ·Multiple Points of control ·Multiple Points of failure ·Certain requirements are common to many distributed systems ­Resource Sharing ­Openness ­Concurrency ­Scalability ­Fault Tolerance ­Transparency 18. Transparency in Distributed Systems ·Distributed systems should be perceived by users and application programmers as a wholerather than as a collection of cooperating components. ·Transparency has different dimensions. ­These represent various properties that distributed systems should have. Access Transparency ·Enables local and remote information objects to be accessed using identical operations. ·Example:SQL Queries Location Transparency ·Enables information objects to be accessed without knowledge of their location. ·Example:Pages in the Web ·Example:Tables in distributed databases