#Hfs file system fault tolerant features software#

In particular, the specification does not define protocols required to achieve interoperability among different ORB implementations.

The FT CORBA specification does not attempt to meet all the availability and reliability requirements of the wide spectrum of today's CORBA-based applications.

#Hfs file system fault tolerant features software#

Rather, FT CORBA complements fault tolerant infrastructures by defining fault tolerant mechanisms for compliant ORBs and services that support the development and operation of fault tolerant software systems. Even so, FT CORBA is not a replacement for fault tolerant infrastructure. A system's deployment environment is generally beyond the scope of FT CORBA although it does discuss the realtionship between FT CORBA and security domains and the use of gateways. In practice, many fault tolerant systems are deployed on fault tolerant infrastructures including specialized operating systems, redundant or fault resilient communications systems, and fault tolerant processors. For many applications, the degree of reliability attained is directly related to the extent of the application's participation in achieving its FT goals. by realizing interfaces used to monitor objects and detect faults, by defining FT properties to be applied to CORBA objects, and by choosing operational styles that control distribution of responsibility between the application and FT CORBA. Applications must collaborate with FT CORBA by realizing certain interfaces, e.g. Applications cannot, however, remain completely unaware. FT CORBA is intended for use by applications that actively participate in achieving fault tolerance as well as applications that rely almost exclusively on FT CORBA's services and supporting features. Similar to other CORBA-based services and ORB features, FT CORBA defines mechanisms, including policies and properties, that application developers can use to adapt FT CORBA to their specific needs on a case-by-case basis. FT CORBA is suitable for a wide range of applications, from large scale business enterprise applications (such as billing, customer management, and financial asset management systems) to mid-scale applications (such as telecommunications and warehousing applications) to distributed, embedded, real-time applications (such as medical equipment control and monitoring systems).

Through application of this framework, applications can attain a degree of reliability beyond what can be achieved through traditional server redundancy. The FT CORBA specification defines an architecture, a set of services, and associated fault tolerance mechanisms that constitute a framework for resilient, highly-available, distributed software systems. Future articles on FT CORBA will introduce the feature objectives for the initial FT CORBA release of The ACE ORB (TAO)В and report on progress as these features are implemented. In this article, we introduce Fault Tolerant CORBA and describe the architecture set forth in the FT CORBA specification. The October 2002 Middleware News BriefВ described the RT CORBA specification. FT CORBA В defines interfaces, QoS policies, and services to enhance the reliability of CORBA applications. RT CORBA В defines standard interfaces and QoS policies that allow applications to configure and control processor resources, communication resources, and memory resources. Two relatively recent OMG specifications that address many of the QoS needs of such applications include Real-time (RT) CORBA and Fault Tolerant (FT) CORBA. Likewise, such systems must continue to function even in the presence of faults.

In many applications, a 'correct' answer, if delivered too late, is considered a failure. Traditional CORBA, which provides only 'best effort' semantics, is not sufficient for the QoS needs of such applications. Many applications require the middleware on which they are built be predictable and reliable. Unfortunately, traditional CORBA-based middleware often cannot meet the demanding quality of service (QoS) needs of certain specialized applications. CORBA's inherent benefits, such as location transparency, platform portability, network transparency, and language independence are important factors in its wide-ranging success. Introduction to Fault Tolerant CORBA byВ Rob Martin, Principal Software EngineerВ andВ Steve Totten, Principal Software Engineer and Partner January 2003 IntroductionД¬ORBA is used in a wide variety of application domains-aerospace and defense, banking and finance, telecommunications, manufacturing, healthcare, even multimedia and entertainment.