As computer technology advances we have to deal with resources on different locations. One of the main problems that has to be solved is how to link decentralized resources together to work as a whole. There are many different types of distributed computing systems and many challenges to overcome in successfully designing one.

The main goals of modern systems are:

• user interface

• data interpretation/representation

  data can come from different sources that are usually technologically very heterogeneous

• transparency

  one can use system without knowing its internal structure and architecture - we can talk about user service access point (uSAP). User transparent environment can be easily implemented in central homogeneous system. It is a problem to implement user transparent (homogeneous)  environment in heterogeneous system that is composed of several technological different computer systems.
  

OSI arhitecture has function implementation that influences user environment homogeneity in session, presentation and application layer - upper layers.  That means that we can't search for solution to transparency in a network - it is a problem of logical binding of processes and users inside of a heterogeneus system.

distributed is not the same as decentralized

• Decentralized system resources

  • Decentralized processing

  • Decentralized control system

  • Decentralized database