Distributed object

Last updated
Image describes communication between distributed objects residing in different machines. Distributed object communication.png
Image describes communication between distributed objects residing in different machines.

In distributed computing, distributed objects[ citation needed ] are objects (in the sense of object-oriented programming) that are distributed across different address spaces, either in different processes on the same computer, or even in multiple computers connected via a network, but which work together by sharing data and invoking methods. This often involves location transparency, where remote objects appear the same as local objects. The main method of distributed object communication is with remote method invocation, generally by message-passing: 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.

Contents

Distributed objects were popular in the late 1990s and early 2000s, but have since fallen out of favor. [1]

The term may also generally refer to one of the extensions of the basic object concept used in the context of distributed computing, such as replicated objects or live distributed objects.

See also Internet protocol suite.

Local vs. distributed objects

Local and distributed objects differ in many respects. [3] [4] Here are some of them:

  1. Life cycle : Creation, migration and deletion of distributed objects is different from local objects
  2. Reference : Remote references to distributed objects are more complex than simple pointers to memory addresses
  3. Request Latency : A distributed object request is orders of magnitude slower than local method invocation
  4. Object Activation : Distributed objects may not always be available to serve an object request at any point in time
  5. Parallelism : Distributed objects may be executed in parallel.
  6. Communication : There are different communication primitives available for distributed objects requests
  7. Failure : Distributed objects have far more points of failure than typical local objects.
  8. Security : Distribution makes them vulnerable to attack.

Examples

The RPC facilities of the cross platform serialization protocol, Cap'n Proto amount to a distributed object protocol. Distributed object method calls can be executed (chained, in a single network request, if needs be) through interface references/capabilities. [5]

Distributed objects are implemented in Objective-C using the Cocoa API with the NSConnection class and supporting objects.

Distributed objects are used in Java RMI.

CORBA lets one build distributed mixed object systems.

DCOM is a framework for distributed objects on the Microsoft platform.

DDObjects is a framework for distributed objects using Borland Delphi.

Jt is a framework for distributed components using a messaging paradigm.

JavaSpaces is a Sun specification for a distributed, shared memory (space based)

Pyro is a framework for distributed objects using the Python programming language.

Distributed Ruby (DRb) is a framework for distributed objects using the Ruby programming language.

See also

Related Research Articles

In distributed computing, a remote procedure call (RPC) is when a computer program causes a procedure (subroutine) to execute in a different address space, which is written as if it were a normal (local) procedure call, without the programmer explicitly writing the details for the remote interaction. That is, the programmer writes essentially the same code whether the subroutine is local to the executing program, or remote. This is a form of client–server interaction, typically implemented via a request–response message-passing system. In the object-oriented programming paradigm, RPCs are represented by remote method invocation (RMI). The RPC model implies a level of location transparency, namely that calling procedures are largely the same whether they are local or remote, but usually, they are not identical, so local calls can be distinguished from remote calls. Remote calls are usually orders of magnitude slower and less reliable than local calls, so distinguishing them is important.

Jakarta Enterprise Beans is one of several Java APIs for modular construction of enterprise software. EJB is a server-side software component that encapsulates business logic of an application. An EJB web container provides a runtime environment for web related software components, including computer security, Java servlet lifecycle management, transaction processing, and other web services. The EJB specification is a subset of the Java EE specification.

In computing, the Java Remote Method Invocation is a Java API that performs remote method invocation, the object-oriented equivalent of remote procedure calls (RPC), with support for direct transfer of serialized Java classes and distributed garbage-collection.

The Common Object Request Broker Architecture (CORBA) is a standard defined by the Object Management Group (OMG) designed to facilitate the communication of systems that are deployed on diverse platforms. CORBA enables collaboration between systems on different operating systems, programming languages, and computing hardware. CORBA uses an object-oriented model although the systems that use the CORBA do not have to be object-oriented. CORBA is an example of the distributed object paradigm.

<span class="mw-page-title-main">Inter-process communication</span> How computer operating systems enable data sharing

In computer science, inter-process communication or interprocess communication (IPC) refers specifically to the mechanisms an operating system provides to allow the processes to manage shared data. Typically, applications can use IPC, categorized as clients and servers, where the client requests data and the server responds to client requests. Many applications are both clients and servers, as commonly seen in distributed computing.

In computer science, an object can be a variable, a data structure, a function, or a method. As regions of memory, they contain value and are referenced by identifiers.

In distributed computing, an object request broker (ORB) is a middleware which allows program calls to be made from one computer to another via a computer network, providing location transparency through remote procedure calls. ORBs promote interoperability of distributed object systems, enabling such systems to be built by piecing together objects from different vendors, while different parts communicate with each other via the ORB.

Message-oriented middleware (MOM) is software or hardware infrastructure supporting sending and receiving messages between distributed systems. MOM allows application modules to be distributed over heterogeneous platforms and reduces the complexity of developing applications that span multiple operating systems and network protocols. The middleware creates a distributed communications layer that insulates the application developer from the details of the various operating systems and network interfaces. APIs that extend across diverse platforms and networks are typically provided by MOM.

In computer science, message passing is a technique for invoking behavior on a computer. The invoking program sends a message to a process and relies on that process and its supporting infrastructure to then select and run some appropriate code. Message passing differs from conventional programming where a process, subroutine, or function is directly invoked by name. Message passing is key to some models of concurrency and object-oriented programming.

The Data Distribution Service (DDS) for real-time systems is an Object Management Group (OMG) machine-to-machine standard that aims to enable dependable, high-performance, interoperable, real-time, scalable data exchanges using a publish–subscribe pattern.

Jakarta XML RPC allows a Jakarta EE application to invoke a Java-based web service with a known description while still being consistent with its WSDL description. JAX-RPC is one of the Java XML programming APIs. It can be seen as Java RMIs over web services. JAX-RPC 2.0 was renamed JAX-WS 2.0. JAX-RPC 1 is deprecated with Java EE 6. The JAX-RPC service utilizes W3C standards like WSDL or Web Service Description Language. The core API classes are located in the Java package javax.xml.rpc.

The Internet Communications Engine, or Ice, is an open-source RPC framework developed by ZeroC. It provides SDKs for C++, C#, Java, JavaScript, MATLAB, Objective-C, PHP, Python, Ruby and Swift, and can run on various operating systems, including Linux, Windows, macOS, iOS and Android.

Replication in computing involves sharing information so as to ensure consistency between redundant resources, such as software or hardware components, to improve reliability, fault-tolerance, or accessibility.

RMI-IIOP denotes the Java Remote Method Invocation (RMI) interface over the Internet Inter-Orb Protocol (IIOP), which delivers Common Object Request Broker Architecture (CORBA) distributed computing capabilities to the Java platform. It was initially based on two specifications: the Java Language Mapping to OMG IDL, and CORBA/IIOP 2.3.1.

.NET Remoting is a Microsoft application programming interface (API) for interprocess communication released in 2002 with the 1.0 version of .NET Framework. It is one in a series of Microsoft technologies that began in 1990 with the first version of Object Linking and Embedding (OLE) for 16-bit Windows. Intermediate steps in the development of these technologies were Component Object Model (COM) released in 1993 and updated in 1995 as COM-95, Distributed Component Object Model (DCOM), released in 1997, and COM+ with its Microsoft Transaction Server (MTS), released in 2000. It is now superseded by Windows Communication Foundation (WCF), which is part of the .NET Framework 3.0.

The Spring Framework is an application framework and inversion of control container for the Java platform. The framework's core features can be used by any Java application, but there are extensions for building web applications on top of the Java EE platform. Although the framework does not impose any specific programming model, it has become popular in the Java community as an addition to the Enterprise JavaBeans (EJB) model. The Spring Framework is open source.

In a distributed computing environment, distributed object communication realizes communication between distributed objects. The main role is to allow objects to access data and invoke methods on remote objects. Invoking a method on a remote object is known as remote method invocation (RMI) or remote invocation, and is the object-oriented programming analog of a remote procedure call (RPC).

<span class="mw-page-title-main">Live distributed object</span>

Live distributed object refers to a running instance of a distributed multi-party protocol, viewed from the object-oriented perspective, as an entity that has a distinct identity, may encapsulate internal state and threads of execution, and that exhibits a well-defined externally visible behavior.

<span class="mw-page-title-main">API</span> Software interface between computers and/or programs

An application programming interface (API) is a way for two or more computer programs to communicate with each other. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how to build or use such a connection or interface is called an API specification. A computer system that meets this standard is said to implement or expose an API. The term API may refer either to the specification or to the implementation.

References

  1. ↑ Microservices and the First Law of Distributed Objects, Martin Fowler, 13 August 2014
  2. ↑ Ostrowski, K., Birman, K., Dolev, D., and Ahnn, J. (2008). "Programming with Live Distributed Objects", Proceedings of the 22nd European Conference on Object-Oriented Programming, Paphos, Cyprus, July 07–11, 2008, J. Vitek, Ed., Lecture Notes in Computer Science, vol. 5142, Springer-Verlag, Berlin, Heidelberg, 463-489, http://portal.acm.org/citation.cfm?id=1428508.1428536.
  3. ↑ W. Emmerich (2000) Engineering distributed objects, John Wiley & Sons Ltd.
  4. ↑ Samuel C. Kendall, Jim Waldo, Ann Wollrath, and Geoff Wyant. 1994. A Note on Distributed Computing. Technical Report. Sun Microsystems, Inc., Mountain View, CA, USA.
  5. ↑ "Cap'n Proto: RPC Protocol".
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.