CISSP考试指南笔记：8.9 分布式计算

A distributed object computing model needs to register the client and server components, which means to find out here they live on the network, what their names or IDs are, and what type of functionality the different components carry out.

Distributed Computing Environment

Distributed Computing Environment (DCE) is a standard developed by the Open Software Foundation (OSF), also called Open Group.

DCE is a set of management services with a communications layer based on RPC. DCE and Distributed Component Object Model (DCOM) offer much of the same functionality. DCOM, however, was developed by Microsoft and is more proprietary in nature.

DCE’s time service provides host clock synchronization and enables applications to determine sequencing and to schedule events based on this clock synchronization. DCOM uses a globally unique identifier (GUID), while DCE uses a universal unique identifier (UUID).

CORBA and ORBs

Common Object Request Broker Architecture (CORBA) is an open object-oriented standard architecture developed by the Object Management Group (OMG).

The CORBA model provides standards to build a complete distributed environment. It contains two main parts: system-oriented components (object request brokers [ORBs] and object services) and application-oriented components (application objects and common facilities).

ORB is the middleware that allows the client/server communication to take place between objects residing on different systems.

COM and DCOM

The Component Object Model (COM) allows for inter-process communication within one application or between applications on the same computer system.

The Distributed Component Object Model (DCOM) supports the same model for component interaction, and also supports distributed inter-process communication (IPC).

Object Linking and Embedding

Object Linking and Embedding (OLE) provides a way for objects to be shared on a local personal computer and to use COM as their foundation. OLE enables objects to be embedded into documents. The capability for one program to call

Another program is called linking. The capability to place a piece of data inside a foreign program or document is called embedding.

Java Platform, Enterprise Edition

Java EE defines a client/server model that is object oriented and platform independent.

Service-Oriented Architecture

A service-oriented architecture (SOA) provides standardized access to the most needed services to many different applications at one time.

The entity that will provide a service in an SOA environment sends a service-description document to a service broker. The service broker is basically a map of all the services available within a specific environment.

Services within an SOA are usually provided through web services. A web service allows for web-based communication to happen seamlessly using web-based standards, as in Simple Object Access Protocol (SOAP), HTTP, Web Services Description Language (WSDL), Universal Description, Discovery and Integration (UDDI), and Extensible Markup Language (XML). WSDL provides a machine-readable description of the specific operations provided by the service. UDDI is an XML-based registry that lists available services.

A mashup is the combination of functionality, data, and presentation capabilities of two or more sources to provide some type of new service or functionality.

Cloud computing is a method of providing computing as a service rather than as a physical product.

Software as a Service (SaaS) is a cloud computing model that allows applications and data to be centrally hosted and accessed by thin clients, commonly web browsers.