Applications in modern enterprises are increasingly dependent on two enabling technologies: high-speed networking and object orientation. These applications, which are becoming more complex and … Expand.
View 3 excerpts, cites background and methods. A significant development in computing in the s has been the move toward more distributed computer systems through network communication facilities. Instead of viewing computers as individual … Expand. A platform for device and computation management. View 1 excerpt, cites background. Framework for middleware executed on mobile devices.
Middleware for Distributed Systems. Wiley Encyclopedia of Computer Science and Engineering. The Impact of Research on Middleware Technology. Seleclting Middleware for N-tier applications.
Transaction processing monitors. Data communications. NAS architecture reference manual. Understanding DCE. Concurrency Control and Recovery in Database Systems. He currently works on repository technology in support of CASE tools. Related Papers. Here, object communication takes place through a middleware system called an object request broker software bus.
Client and the server do not interact with each other directly. Client and server have a direct connection to its proxy which communicates with the mediator-broker. A server provides services by registering and publishing their interfaces with the broker and clients can request the services from the broker statically or dynamically by look-up.
Broker is responsible for coordinating communication, such as forwarding and dispatching the results and exceptions. It can be either an invocation-oriented service, a document or message - oriented broker to which clients send a message.
It is responsible for brokering the service requests, locating a proper server, transmitting requests, and sending responses back to clients. It provides APIs for clients to request, servers to respond, registering or unregistering server components, transferring messages, and locating servers. Stubs are generated at the static compilation time and then deployed to the client side which is used as a proxy for the client.
Client-side proxy acts as a mediator between the client and the broker and provides additional transparency between them and the client; a remote object appears like a local one.
The proxy hides the IPC inter-process communication at protocol level and performs marshaling of parameter values and un-marshaling of results from the server. Skeleton is generated by the service interface compilation and then deployed to the server side, which is used as a proxy for the server. Server-side proxy encapsulates low-level system-specific networking functions and provides high-level APIs to mediate between the server and the broker.
It receives the requests, unpacks the requests, unmarshals the method arguments, calls the suitable service, and also marshals the result before sending it back to the client.
A bridge can connect two different networks based on different communication protocols. It mediates different brokers including DCOM,. Bridges are optional component, which hides the implementation details when two brokers interoperate and take requests and parameters in one format and translate them to another format. A service is a component of business functionality that is well-defined, self-contained, independent, published, and available to be used via a standard programming interface.
The connections between services are conducted by common and universal message-oriented protocols such as the SOAP Web service protocol, which can deliver requests and responses between services loosely. Loose coupling of service—orientation provides great flexibility for enterprises to make use of all available service recourses irrespective of platform and technology restrictions.
The implementation of a service will not affect the application of the service as long as the exposed interface is not changed. A client or any service can access other services regardless of their platform, technology, vendors, or language implementations. Reusability of assets and services since clients of a service only need to know its public interfaces, service composition.
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