qos -enabled middleware
DESCRIPTION
QoS -enabled middleware. by Saltanat Mashirova. Distributed applications. - PowerPoint PPT PresentationTRANSCRIPT
QoS-enabled middleware
by Saltanat Mashirova
Distributed applicationsDistributed applications have distinctly different
characteristics than conventional desktop or back office applications in that the right answer delivered too late can become the wrong answer, i.e., failure to meet key QoS requirements can lead to catastrophic consequences. Middleware that can satisfy stringent quality of service (QoS) requirements, such as predictability, latency, efficiency, scalability, dependability, and security, is increasingly being applied to DRE application development.
Limits of Conventional Middleware- Lack of functional boundaries- Lack of generic server standards- Lack of software configuration and deployment
standards
Component MiddlewareComponent middleware is a class of middleware
that enables reusable services to be composed, configured, and installed to create applications rapidly and robustly.
How component middleware overcome those limitations Creating a virtual boundary around larger
application component implementations that interact with each other only through well-defined interfaces
Defining standard container mechanisms needed to execute components in generic component servers
Specifying the infrastructure to assemble, package, and deploy components throughout a distributed environment
Component MiddlewareCORBA Component Model (CCM) is an example of
component middlewareThe CCM specification extends the CORBA object
model to support the concept of components and establishes standards for implementing, packaging, assembling, and deploying component implementations.
Component is an implementation entity that exposes a set of ports, which are named interfaces and connection points that components use to collaborate with each other
Client View of CCM Components
Overview of the CCM Run-time Architecture
Limitations of Component MiddlewareIt doesn’t give us:Ways to specify end-to-end QoS requirements, i.e.
QoS Characteristics and QoS ValuesWays to specify adaptation strategies for how
Resource Consuming Components can coordinate with other entities in order to meet QoS requirements
Ways to specify QoS management which cross multiple system and application level boundaries
QoSDue to the limitations described above, it is
necessary to extend standard middleware specifications so that they provide better abstractions for controlling and managing both functional and QoS aspects of DRE systems. What is needed is QoS-enabled component middleware that preserves existing support for heterogeneity in standard component middleware.
CIAOCIAO supports Lightweight CCM mechanisms that
enable the specification, validation, packaging, configuration, and deployment of component assemblies and integrates these mechanisms with TAO’s Real-time CORBA features, such as thread-pools, lanes, and client-propagated and server-declared policies.
DAnCEDAnCE is a middleware framework for CIAO based
on the OMG’s Deployment and Configuration specification which standardizes many deployment and configuration aspects of component-based distributed applications, including component configuration, assembly, and packaging; package configuration and deployment; and resource configuration and management