Big Endian vs Little Endian

[Little Endian System]
[Big Endian System]
  • AIX on POWER
  • AmigaOS on PowerPC and 680×0
  • HP-UX on Itanium and PA-RISC
  • Linux on MIPS, SPARC, PA-RISC, POWER, PowerPC, 680×0, ESA/390, and z/Architecture
  • Mac OS on PowerPC and 680×0
  • Mac OS X on PowerPC
  • MVS and DOS/VSE on ESA/390, and z/VSE and z/OS on z/Architecture
  • Solaris on SPARC

Challenges of a Distributed System

  • Heterogeneity – applies to networks computer hardware; operating systems; programming languages; implementations by different developers
  • Openness – interfaces should be publicly available to ease inclusion of new components
    Security – confidentiality(protection against disclosure to unauthorized users), integrity(protection against alteration or corruption), availability(protection against interference with the means to access the resources)
  • Scalability – System should work efficiently with an increasing number of users; System performance should increase with inclusion of additional resources
  • Failure handling – detecting failures, masking failure (hidden or made less severe), recovery from failure, redundancy
  • Concurrency – Several clients will attempt to access a shared resource at the same time, producing inconsistent results
  • Transparency
    • access transparency(enables local and remote information objects to be accessed using identical operations)
    • location transparency(enables information objects to be accessed without knowledge of their physical or network location)
    • name transparency(incorporates a global naming scheme)
    • concurrent transparency (enables several processes to operate concurrently using shared information objects without interference between them)
    • replication transparency(enables multiple instances of information objects to be used to increase reliability and performance without knowledge of the replicas by users or application programmers)
    • migration transparency(allows the movement of resources and clients within a system without affecting the operation of users or programs)
    • failure transparency(enables the concealment of faults, allowing users and application programs to complete their tasks despite the failure of hardware or software components)
    • performance transparency(allows the system to be reconfigured to improve performance as loads vary)
    • scaling transparency (allows the system and applications to expand in scale without change to the system structure or the application algorithms)
  • Quality of Service (QoS) – ability to meet service requirements for applications


Openness (개방성) – offers services according to standard rules that describe the syntax and semantics of those services. Such rules are formalized in protocols. 서로 상이한 요소 간에 interoperability (호환성), portability (이식성) 및 scalability (확장성)이 가능하도록 함

Interoperability (호환성) – characterizes to the extent by which two implementations of systems or components from different manufacturers can co-exist and work together by merely relying on each other’s services as specified by a common standard.

Portability (이식성) – characterizes to what extent an application developed for a distributed system A can be executed without modification on a different distributed system B that implements the same interfaces as A.

Scalability (확장성) – easy to add new components or replace existing ones without affecting those components that stay in place.