Distributed objects are software modules that are designed to work together, but reside either in multiple computers connected via a network or in different processes inside the same computer. A computer is a Machine that manipulates data according to a list of instructions. A computer network is a group of interconnected Computers. Networks may be classified according to a wide variety of characteristics In computing a process is an instance of a Computer program that is being sequentially executed by a computer system that has the ability to run several computer One object sends a message to another object in a remote machine or process to perform some task. The results are sent back to the calling object.
See also Internet protocol suite. The Internet Protocol Suite (commonly TCP/IP) is the set of Communications protocols used for the Internet and other similar networks
Local vs Distributed Objects
Local and distributed objects differ in many respects. [1] Here are some of them:
- Life cycle : Creation, migration and deletion of distributed objects is different from local objects
- Reference : Remote references to distributed objects are more complex than simple pointers to memory addresses
- Request Latency : A distributed object request is orders of magnitude slower than local method invocation
- Object Activation : Distributed objects may not always be available to serve an object request at any point in time
- Parallelism : Distributed objects may be executed in parallel.
- Communication : There are different communication primitives available for distributed objects requests
- Failure : Distributed objects have far more points of failure than typical local objects
- Security : Distribution makes them vulnerable to attack.
Examples
Distributed objects are implemented in Objective-C using the Cocoa API with the NSConnection class and supporting objects. Objective-C is a reflective, object-oriented Programming language which adds Smalltalk -style messaging to C. Cocoa is Apple Inc 's native Object-oriented application program environment for the Mac OS X Operating system
Distributed objects are used in Java RMI. The Java Remote Method Invocation API, or Java RMI, is a Java application programming interface for performing the object equivalent of Remote procedure
CORBA lets one build distributed mixed object systems. The Common Object Requesting Broker Architecture (CORBA is a standard defined by the Object Management Group (OMG that enables software components written
DCOM is a framework for distributed objects on the Microsoft platform. Component Object Model ( COM) is an interface standard for Software componentry introduced by Microsoft in 1993
DDObjects is a framework for distributed objects using Borland Delphi. DDObjects is a Remoting framework for Borland Delphi and C++ Builder.
JavaSpaces is a Sun specification for a distributed, shared memory (spaces based)
Pyro is a framework for distributed objects using the Python programming language. A tuple space is an implementation of the associative memory paradigm for parallel/distributed computing Python is a general-purpose High-level programming language. Its design philosophy emphasizes programmer productivity and code readability
Distributed Ruby (DRb) is a framework for distributed objects using the Ruby programming language. Distributed Ruby or DRb allows Ruby programs to communicate with each other on the same machine or over a network Ruby is a dynamic, reflective, general purpose Object-oriented programming language that combines syntax inspired by Perl with Smalltalk
References
- ^ W. Emmerich (2000) Engineering distributed objects, John Wiley & Sons Ltd.
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