Four goals of Distributed computing

Openness: an open distributed system is a system which gives set of rules describing syntax and semantics of communication. Where syntax gives how to communicate. E.g. programming language. And semantics gives what to communicate. Example: type of data.

Connecting users and resources: distributed system is built to allow communication between user and resource irrespective of their physical location. E.g. accessing website which are far away.

Scalability: is the ability to expand the system. Scalability can be in either three directions. First a system can be scalable with respect to its size, meaning that we can add more user and resources to the system. Second a geographically scalable system is one in which the users and resources may lie far apart. Third a system can be administratively scalable meaning that it can still be easy to manage even if it spans many independent administrative organizations.

Transparency: a transparent distributed system is system which hides’s internal complexity and n number computers involved and presents itself to its users, application as single coherent system.